Diagnosing a 2003 Ford T Bird throttle defaulting. Automotive Test Solutions eSCAN ELITE & eSCOPE ELITE are both used to determine problems. www.automotive... www.automotive...
Mr. Thompson, could i move to Albuquerque and become your apprentice? Thank you for the videos you always post. Every time you post one it feels like i was waiting for another episode of my favorite series. You are in a league of your own. 😄
You are a next level technician. You're an engineer capable of attacking any problem situation. I hope that you can keep teaching us the possibilities in diagnostics.
@@SuperMarioDiagnostics He's like the conductor of the Escope Symphony Orchestra -- Haa ... Sometimes he just leaves me speechless the way he finds stuff.
Berny love it when you said, “…keep your eye on the ball!” Sounded like a real teacher who’s passionate about making sure your students staying focus. I’ve been watching your videos since last year and honestly you are the best (the goat) when it comes to the oscilloscope and everyone else is in a far distance second place.
On Nissan relays the fly back voltage is controlled by the relay itself, and unfortunately the suppression feature is not shown in OE diagrams?The diode or resistor is built in. I'm wondering if simply replacing the relay may have repaired it?
I learned that protection was in every car Ford made with a cycling A/C clutch back in the 1980's. It's in a plastic enclosure about 2 inches long, and taped to the harness by the a/c clutch connector. If it gets damaged or removed by someone, it's going to allow those voltage spikes. I learned it in school and overheard our lead tech and parts manager trying to figure one out one day back in 1987. They called Mercedes to find out about it. I happened to overhear, so I pointed it out to them in the harness. Theirs had an open that was causing a driveability issue then, in 87. So Ford definitely knows and built them that way ages ago. It would be interesting to see if the T-bird doesn't have one? Or whether it's open? Or is the harness damaged? You need an EVTM to see if it's in their diagram. That's the troubleshooter manual. It's not known for having misprints, omissions, or wrong diagrams. It's what ford techs used before computer displays and live data streams just handed us answers like we have available to us now. It sure was good deduction to ask the customer about how you make it act up and when, then think about what systems are in use, and what circumstances the car goes through at the event. The clutch powers off, releases, and the left over energy has to dissipate. It can, so it does, (without a diode across it) go back and kick the processor. That would be bad. If you're at a wrecking yard, you can grab a spare one to use and put in for the test. They're often black or yellow plastic and wrapped with tape on the A/C harness
@@googacct yes it's likely it was designed with the protection, the EVTM diagram has a correct drawing almost always. These other sources for diagrams might be where it's not depicted? I don't know. Too bad they didn't have him repair the car too, so we could see. You can order real OEM literature at parts from HELM publications last time I checked. But they could share that page of info with you in a dealer service department if you find caring people who want to see it corrected. They used to say it's your car, but it's our baby. That may have been a local thing. Before all the smart people started in on things.
Electronic Throttle Control (ETC) is essentially a closed loop servo positional system, which will have a closed loop positional (and perhaps velocity) control algorithm (most likely PI). The H-Bridge current control (PWM voltage modulation) is most likely four quadrant control, especially if the ETC motor has a default return spring. The positional information, throttle position and pedal position, is redundant in order to meet a specified safety level of operation. This safety requirement can also influence the processor selection with redundant computational units running in parallel. The most important aspect of the throttle positional information is that it indicates the true position of the throttle plate (at the needed resolution), secondary is in indicating a fault condition.
Mr Bernie I have bought the your scan tool about 8 to 9 months now and without luck it just not plotting the fuel trim on the graph when you do that drive
To be effective at clamping the inductive electric clutch voltage spike, the coil clamping diode should be at or near the coil itself. On this year T-Bird the diode is on the compressor housing which is only about 8 inches from the clutch coil. The problem with the negative unclamped coil voltage spike is that, because the battery is in the trunk, there is considerable common ground impedance, across which the voltage spike can influence control module ground enough to cause a processor reset. The question is why is the electronic control module resetting? Is it due to loss of power supply causing a reset, or is the modulating ground triggering a reset circuit, either internal to the microcontroller or external at the power supply. The main vehicle grounds should be checked to see if any common splice or connection point is loose or corroded. The goal would be to minimize the return current common ground impedance. If the battery return is through the chassis then the chassis ground connection points should be checked for corrosion. The AC compressor coil diode on the compressor housing is large, perhaps having a power rating like an alternator diode (75 to 100 Watts). The diode is held by a bracket so it looks like you could replace it without replacing the compressor. The ECM Ignition IGBTs (low side drive, pulling the ignition coil to ground) have an on-board active clamp starting at around 420 Volts to protect the IGBT. It is important to get a high flyback voltage to have a high energy spark (transformer action giving a high ignition voltage at the plug), but not too high to damage the IGBT or force it to clamp excessive energy, which will lead to the IGBT failing due to exceeding its safe operating region usually due to excessive power dissipation (component getting hot). If ECM is designed correctly and the vehicle power supply (battery and alternator) have low source and ground impedance (imagine the ECM placed directly across the battery which is next to the alternator as an ideal case), then the high ignition flyback voltage will not effect the power supply or the microcontroller. The term "set gates out" is a reference to randomly and catastrophically changing microcontroller logic gate states which change the normal program flow (e.g. program execution counter in error) and thus will eventually cause a module reset. The ECM I/O, which includes all the circuits on the module connector, are very robust in terms of electrical disturbances including ESD. So, a voltage overstress which results in a microcontroller reset is most likely apart of the module power supply. The ECM can manage high voltages and currents, if the loads do not excessively modulate the power or ground common impedance. The Microcontroller in the ECM never drives coil-on-plug coils directly, they use a smart pre-driver (for diagnostics (OBD-II), usually through a SPI channel) and then the pre-driver powers the ignition IGBT. The injectors are done in a similar manner, the pre-driver powers the injection N-Channel Smart MOSFET (low side drive), in some cases the pre-driver and MOSFETs are on one special power driver IC. Here again the Microcontroller monitors injection power device operation through the use of a SPI channel serial link. The main reason to put the IGBTs at the coil-on-plug coils (known as a smart coil) is not that the flyback voltage will cause a module reset, it is due to power dissipation. The ignition IGBTs on-board the ECM produce a great deal of heat (actually the largest heat producer at modest engine RPMs), which has to be managed (dissipated) in some fashion. This is why when a Ford EEC with IGBTs on-board fail (misfire, ignition out on one cylinder), the culprit is usually the IGBT that runs the hottest in the module.
Question. When the Clutch Relay Contacts "Open" causing the Magnetic Field to collapse, how does the "Spike" get across the "Open" Relay Contacts onto the DC Supply ??
I'll take a shot at this question. It is probably through induction similar as an ignition coil. The energy travels the easiest path. Since everything else has good insulation the shortest path would be in that tiny relay.
I don't think the voltage spike jump the gap between the relay contacts because you would need kV to do so. Just as he said, the engineers are aware of these spikes and so they install diodes in every circuit which involves inductors even the relay coils must have one. To answer your question, the huge spike is reaching the computer through the bad AC compressor diode that is connected to ground as the computer. I'm not totally sure but it's the only way I think
@@prashanshan7125 Kind of long winded but here is some what I got out of the video. You may want to view it again. Bernie takes the shortest data driven path as possible. Both signals did show on Bernie's first connection set up. The nuance that he delivers on each video is to follow a fact driven diagnostic procedure. Two things during the video he pressed home was to establish a baseline of how the car was performing. The first being careful to follow the customer complaint while identifying any other issues. The second was to get a good description of when the issue occurs, when he gathered the time and place of the event. After which his first connection shown that the throttle actuator was receiving the correct inputs. This data then delivered an event that he could replicate. Detailed customer information then identified the next item to test. Since his first connection identified what to watch for, there was no need to view all the signals while testing the next system. He then cleared the screen to making it visually easier to see. If you were looking for reference signals from the accelerator pedal you would have been on a longer journey.
Master fix... Sometimes power train Network lines to for example 2kw + audio amplifier in boot feed line not properly fitted in engine bay harness making noise and limp mode.for sure
was that a 4pin or 5 pin relay? and was there 4 or 5 terminals in the fuse block? was that the correct relay? wiring diagrams accuracy is more and more becoming a crapshoot.
A diode only allows current to flow in one direction. The line across the point of the diode symbol will block conventional current flow(positive to negative). So no current will flow through the diode when the relay is closed powering up the clutch coil. When the relay opens and the magnetic field of the clutch coil collapses, the polarity reverses since the field is now collapsing and that allows current to flow in a loop through the diode and coil windings. I still have trouble understating how the spike affect the computer since it’s isolated on the load side and not the control/pcm side. Maybe mutual induction like others have said or maybe the relay acts as a capacitor with that much of a spike causing the control winding to flow current even though it’s not directly connected…? Be cool if we could see the pcm side of the relay on the scope too. Its crazy the problems this guy is able to diagnose.
In normal operation, the diode is the "wrong way round" for any current to flow through it. In the diagram, current flow is top to bottom but the diode is installed with the arrow bottom to top. When you disconnect power to a coil, it wants to try to keep current flowing in the same direction as the magnetic field collapses. Think of it a bit like a flywheel. So instead of current being pushed into the top terminal of the coil, the coil is now pulling on the top terminal trying to get some current in - *so the voltage at the top terminal goes negative with respect to the grounded end of the coil*. You can see this at 41:31 Now with the diode added, there is a path for the current to take when the voltage goes negative. Because losses are a thing, the current will flow round in a circle between coil and diode but constantly falling, the negative spike will now be limited to under 1V, the "forward" conducting voltage of the diode. You can see this in the waveform at 42:05 and also note that current flows for about 250ms before tailing off. And yes, this makes the AC clutch release more slowly.
MY QUESTION IS, WHY IT MAKES THE PROBLEM NOW. THE COMPRESSOR CLUTCH HAD NOT NOTHING FOR THE SUPRESSION OF THIS SPIKE WHEN THE CAR WAS NEW THAT S THE SAME CLUTCH, WHY IT DOES THE PROBLEM NOW, WHAT IS CHANGED IN THE COIL OF COMPRESSOR CLUTCH.
Great video that goes well beyond this specific issue. My T-bird had the same symptoms. It turned two coil packs were producing voltage spikes (as seen on a O-Scope). I replaced all of the coil packs and spark plugs parts as parts cost was quite low. I am an electrical engineer that just retired from repairing semiconductor manufacturing equipment for 40 years. This reminds me of the most difficult problem in my career We had a semiconductor manufacturing tool that had an intermittent fly back diode. It would fail once every 2 weeks. We used multiple O-scope to track down the voltage spike. A one dollar part kept a million dollar tool down for 2 months.
Tuning into the ac clutch turning on and off triggering the fault was the instinct that lead to the final test and ultimately the fix. Love not only the scope analysis, but the combination of skill sets that solved the problem. Ps I prefer breakout relays for any relay testing, but it was cool to know of a wire so fine that you can slip it into the terminals without opening them up when the relays inserted. I think that’s also a little bit of old school in there from Bernie! Lol! Nice!
Yes, knowing that the customer uses the AC was the turning point especially when the previous shop said the throttle defaulted all the time and he wasn't seeing it default initially.
Ford normally puts their diodes in the fuse fox with the fuses I've replaced afew when people jumpstart the car backwards.. I see one for the PCM power but not the A/C clutch..
Back e.m.f. On any relay in all electronics is always needed You obviously no electronics which is needed to repair modern cars. I have put 4001 diodes on relays on old cars because customers said when going from hi beam to low a ticking sound came across on the radio. I love your vids great diagnostics.
Been nice to find the diode. I have access to Ford Service Info and it too doesn't show the diode. Bet the coil has it right at the connector, or very close by. Be neat to follow up on this car. Bet the coil is bad too. Thanks Bernie.
Cool case study Bernie! How exactly did the voltage spike on the load side of the AC clutch relay make it back to the PCM? We didn't see any evidence on the other channels of the scope 🤔
Ivan, I’m assuming inductance inside of the relay, high voltage on the load contacts carried over to control coil through inductance. My guess but I’m not sure I actually came here to ask the same question
@@PineHollowAutoDiagnostics or the high voltage reverse spike is going into the fuse box and making is way back to the PCM. The relay load and coil power feeds are connected together inside the fuse box even though they have separate fuses. Seen blower motor spinning down set SIR trouble codes due to back EMF.
Being that the battery is in the trunk, it may be more helpful to look at signals at the under hood main ground to understand what the module voltages are when the engine is running (powered by the alternator). Mainly for two reasons, the first is the long ground reference lead will pick up a considerable amount of noise, the second is we want to understand the I/O signals as close to the module connector as possible, which is under hood or near the firewall. Ideally, ground for troubleshooting a module would be directly at the module ground as a reference. This is important because what you can see is how the power and ground impedance relative to the battery in the trunk can be modulated by electrical overstress.
Great video as usual, so you set the diode up in reverse bias to absorb flyback because the grd potential would be higher + than the kickback? Is the kickback always negative value? Like the antenna instead of using multiple channels and multiple e-cops. Do you sell those? I had a Pico but now I'm spoiled rotten with the E-Scope and E-Scan. Thanks
So it can't be built this way or right off the bat this seems like to me it would be present off the showroom floor, but I thin, you are saying either the diode ground is lost or spikes over time make the ic sick enough to malfunction. That would necessarily necessitate a new computer which is only a partial solution for this Tbird. Have to be a big diode with high voltage and current capability.
Mr. Thompson, could i move to Albuquerque and become your apprentice? Thank you for the videos you always post. Every time you post one it feels like i was waiting for another episode of my favorite series. You are in a league of your own. 😄
I think we all feel like that here
me too
Wait untill you meet and talk to him, he is a friendly and knowledgeable guy!
I study everyday and I'm having troubles everyday. Lmao
You are a next level technician. You're an engineer capable of attacking any problem situation. I hope that you can keep teaching us the possibilities in diagnostics.
"I don't have enough leads." --Legend
You a legend too G
Bernie's got more channels than cable TV;-)
@@alexmessina3383 yeah, but he's got the skills to back it up!
@@SuperMarioDiagnostics He's like the conductor of the Escope Symphony Orchestra -- Haa ... Sometimes he just leaves me speechless the way he finds stuff.
Berny love it when you said, “…keep your eye on the ball!” Sounded like a real teacher who’s passionate about making sure your students staying focus. I’ve been watching your videos since last year and honestly you are the best (the goat) when it comes to the oscilloscope and everyone else is in a far distance second place.
Professor Thompson your diagnosis is second to none.
A great lesson in every one of your case studies. Thank you Bernie!!
On Nissan relays the fly back voltage is controlled by the relay itself, and unfortunately the suppression feature is not shown in OE diagrams?The diode or resistor is built in. I'm wondering if simply replacing the relay may have repaired it?
I learned that protection was in every car Ford made with a cycling A/C clutch back in the 1980's.
It's in a plastic enclosure about 2 inches long, and taped to the harness by the a/c clutch connector.
If it gets damaged or removed by someone, it's going to allow those voltage spikes.
I learned it in school and overheard our lead tech and parts manager trying to figure one out one day back in 1987.
They called Mercedes to find out about it.
I happened to overhear, so I pointed it out to them in the harness.
Theirs had an open that was causing a driveability issue then, in 87.
So Ford definitely knows and built them that way ages ago.
It would be interesting to see if the T-bird doesn't have one? Or whether it's open?
Or is the harness damaged?
You need an EVTM to see if it's in their diagram. That's the troubleshooter manual.
It's not known for having misprints, omissions, or wrong diagrams.
It's what ford techs used before computer displays and live data streams just handed us answers like we have available to us now.
It sure was good deduction to ask the customer about how you make it act up and when, then think about what systems are in use, and what circumstances the car goes through at the event.
The clutch powers off, releases, and the left over energy has to dissipate. It can, so it does, (without a diode across it) go back and kick the processor.
That would be bad.
If you're at a wrecking yard, you can grab a spare one to use and put in for the test.
They're often black or yellow plastic and wrapped with tape on the A/C harness
That makes more sense to me. The car is 19 years old and only recently developed the problem. So it would seem unlikely there was never a diode there.
@@googacct yes it's likely it was designed with the protection, the EVTM diagram has a correct drawing almost always.
These other sources for diagrams might be where it's not depicted?
I don't know.
Too bad they didn't have him repair the car too, so we could see.
You can order real OEM literature at parts from HELM publications last time I checked. But they could share that page of info with you in a dealer service department if you find caring people who want to see it corrected.
They used to say it's your car, but it's our baby.
That may have been a local thing.
Before all the smart people started in on things.
Electronic Throttle Control (ETC) is essentially a closed loop servo positional system, which will have a closed loop positional (and perhaps velocity) control algorithm (most likely PI). The H-Bridge current control (PWM voltage modulation) is most likely four quadrant control, especially if the ETC motor has a default return spring. The positional information, throttle position and pedal position, is redundant in order to meet a specified safety level of operation. This safety requirement can also influence the processor selection with redundant computational units running in parallel. The most important aspect of the throttle positional information is that it indicates the true position of the throttle plate (at the needed resolution), secondary is in indicating a fault condition.
Never would of thought of that. Hats off good thinking.
Crazy diagnoses this was an excellent video to get him flying again.
Hour well spent with mr Bernie. Thanks a lot.
Excellent sir , never disappointed , thanks for sharing .
Amazing diag , you're on top of your game as always 💪
Mr Bernie I have bought the your scan tool about 8 to 9 months now and without luck it just not plotting the fuel trim on the graph when you do that drive
Are you sure that someone didn't change the relay for one that didn't have a diode? Great video
To be effective at clamping the inductive electric clutch voltage spike, the coil clamping diode should be at or near the coil itself. On this year T-Bird the diode is on the compressor housing which is only about 8 inches from the clutch coil.
The problem with the negative unclamped coil voltage spike is that, because the battery is in the trunk, there is considerable common ground impedance, across which the voltage spike can influence control module ground enough to cause a processor reset. The question is why is the electronic control module resetting? Is it due to loss of power supply causing a reset, or is the modulating ground triggering a reset circuit, either internal to the microcontroller or external at the power supply.
The main vehicle grounds should be checked to see if any common splice or connection point is loose or corroded. The goal would be to minimize the return current common ground impedance. If the battery return is through the chassis then the chassis ground connection points should be checked for corrosion.
The AC compressor coil diode on the compressor housing is large, perhaps having a power rating like an alternator diode (75 to 100 Watts). The diode is held by a bracket so it looks like you could replace it without replacing the compressor.
The ECM Ignition IGBTs (low side drive, pulling the ignition coil to ground) have an on-board active clamp starting at around 420 Volts to protect the IGBT. It is important to get a high flyback voltage to have a high energy spark (transformer action giving a high ignition voltage at the plug), but not too high to damage the IGBT or force it to clamp excessive energy, which will lead to the IGBT failing due to exceeding its safe operating region usually due to excessive power dissipation (component getting hot).
If ECM is designed correctly and the vehicle power supply (battery and alternator) have low source and ground impedance (imagine the ECM placed directly across the battery which is next to the alternator as an ideal case), then the high ignition flyback voltage will not effect the power supply or the microcontroller. The term "set gates out" is a reference to randomly and catastrophically changing microcontroller logic gate states which change the normal program flow (e.g. program execution counter in error) and thus will eventually cause a module reset. The ECM I/O, which includes all the circuits on the module connector, are very robust in terms of electrical disturbances including ESD. So, a voltage overstress which results in a microcontroller reset is most likely apart of the module power supply. The ECM can manage high voltages and currents, if the loads do not excessively modulate the power or ground common impedance.
The Microcontroller in the ECM never drives coil-on-plug coils directly, they use a smart pre-driver (for diagnostics (OBD-II), usually through a SPI channel) and then the pre-driver powers the ignition IGBT. The injectors are done in a similar manner, the pre-driver powers the injection N-Channel Smart MOSFET (low side drive), in some cases the pre-driver and MOSFETs are on one special power driver IC. Here again the Microcontroller monitors injection power device operation through the use of a SPI channel serial link.
The main reason to put the IGBTs at the coil-on-plug coils (known as a smart coil) is not that the flyback voltage will cause a module reset, it is due to power dissipation. The ignition IGBTs on-board the ECM produce a great deal of heat (actually the largest heat producer at modest engine RPMs), which has to be managed (dissipated) in some fashion. This is why when a Ford EEC with IGBTs on-board fail (misfire, ignition out on one cylinder), the culprit is usually the IGBT that runs the hottest in the module.
Question. When the Clutch Relay Contacts "Open" causing the Magnetic Field to collapse, how does the "Spike" get across the "Open" Relay Contacts onto the DC Supply ??
I'll take a shot at this question. It is probably through induction similar as an ignition coil. The energy travels the easiest path. Since everything else has good insulation the shortest path would be in that tiny relay.
I don't think the voltage spike jump the gap between the relay contacts because you would need kV to do so. Just as he said, the engineers are aware of these spikes and so they install diodes in every circuit which involves inductors even the relay coils must have one. To answer your question, the huge spike is reaching the computer through the bad AC compressor diode that is connected to ground as the computer. I'm not totally sure but it's the only way I think
Inductive Coupling
2 ref signals of the throttle did not show it with scope on it.. why.?
@@prashanshan7125 Kind of long winded but here is some what I got out of the video. You may want to view it again. Bernie takes the shortest data driven path as possible.
Both signals did show on Bernie's first connection set up. The nuance that he delivers on each video is to follow a fact driven diagnostic procedure. Two things during the video he pressed home was to establish a baseline of how the car was performing. The first being careful to follow the customer complaint while identifying any other issues. The second was to get a good description of when the issue occurs, when he gathered the time and place of the event.
After which his first connection shown that the throttle actuator was receiving the correct inputs. This data then delivered an event that he could replicate. Detailed customer information then identified the next item to test.
Since his first connection identified what to watch for, there was no need to view all the signals while testing the next system. He then cleared the screen to making it visually easier to see.
If you were looking for reference signals from the accelerator pedal you would have been on a longer journey.
Thanks for the great video Bernie! I had one in a semi one time that the VECU locked up and I just installed a relay with a diode in it for the fix!
Master fix... Sometimes power train Network lines to for example 2kw + audio amplifier in boot feed line not properly fitted in engine bay harness making noise and limp mode.for sure
What a great lesson Bernie.Brilliant
was that a 4pin or 5 pin relay? and was there 4 or 5 terminals in the fuse block? was that the correct relay? wiring diagrams accuracy is more and more becoming a crapshoot.
This might be a stupid question but is there a certain diode you used for this situation or any diode will do
Hey! Burnet grate video! Thanks Teddy Moore! 👍👍👍👏👏👏👏
Great video again Bernie!
Great case study!
Isn't there a diode in the fuse box like most fords?
Thanks for sharing.
I defy you to go to any local dealer and find a tech that knows more about how a fuel injection system works. Dude dreams in injection algorithms.
So how does the suppression diode only suprress the inductive spike but not lead the clutch supply voltage to earth?
A diode only allows current to flow in one direction. The line across the point of the diode symbol will block conventional current flow(positive to negative). So no current will flow through the diode when the relay is closed powering up the clutch coil. When the relay opens and the magnetic field of the clutch coil collapses, the polarity reverses since the field is now collapsing and that allows current to flow in a loop through the diode and coil windings. I still have trouble understating how the spike affect the computer since it’s isolated on the load side and not the control/pcm side. Maybe mutual induction like others have said or maybe the relay acts as a capacitor with that much of a spike causing the control winding to flow current even though it’s not directly connected…? Be cool if we could see the pcm side of the relay on the scope too. Its crazy the problems this guy is able to diagnose.
In normal operation, the diode is the "wrong way round" for any current to flow through it.
In the diagram, current flow is top to bottom but the diode is installed with the arrow bottom to top.
When you disconnect power to a coil, it wants to try to keep current flowing in the same direction as the magnetic field collapses. Think of it a bit like a flywheel.
So instead of current being pushed into the top terminal of the coil, the coil is now pulling on the top terminal trying to get some current in - *so the voltage at the top terminal goes negative with respect to the grounded end of the coil*. You can see this at 41:31
Now with the diode added, there is a path for the current to take when the voltage goes negative.
Because losses are a thing, the current will flow round in a circle between coil and diode but constantly falling, the negative spike will now be limited to under 1V, the "forward" conducting voltage of the diode.
You can see this in the waveform at 42:05 and also note that current flows for about 250ms before tailing off. And yes, this makes the AC clutch release more slowly.
Wow Just Wow Amazing Find and Video as Always
"I dont have enough leads" - Bernie Thompson, with 8 leads in use.---The Michael Jordan of automotive diagnostics. Pay attention ppl.
I would have put a relay with diode suppression. But great video.
Bernie is the goat
True Technical Professional
Which type of diode was used? Means parameter…
real good info !
Lisle makes a relay tester.
Great job BERNIE THANK YOU
MY QUESTION IS, WHY IT MAKES THE PROBLEM NOW. THE COMPRESSOR CLUTCH HAD NOT NOTHING FOR THE SUPRESSION OF THIS SPIKE WHEN THE CAR WAS NEW THAT S THE SAME CLUTCH, WHY IT DOES THE PROBLEM NOW, WHAT IS CHANGED IN THE COIL OF COMPRESSOR CLUTCH.
Fantastic video. Do you watch scannerdanner? I’ve learned so much from both of you.
Pretty sure scannerdanner watches Bernie.
Thanks Bernie!
Can u tell me a way so i can be perfect in this language or book
People complained about electric throttle body whine? LOL
I wish I had his skill with a scan tool.
Amazing 👍👍👍👍👍👍
I will truly appreciate if you look in the matter for me
I guess this one is not a real diagram
The bird won't fly Ha ha ha !!!!!!!!!!!!!!!!!!!!!!!!!!!
increíble
Great video that goes well beyond this specific issue. My T-bird had the same symptoms. It turned two coil packs were producing voltage spikes (as seen on a O-Scope). I replaced all of the coil packs and spark plugs parts as parts cost was quite low. I am an electrical engineer that just retired from repairing semiconductor manufacturing equipment for 40 years. This reminds me of the most difficult problem in my career We had a semiconductor manufacturing tool that had an intermittent fly back diode. It would fail once every 2 weeks. We used multiple O-scope to track down the voltage spike. A one dollar part kept a million dollar tool down for 2 months.
Tuning into the ac clutch turning on and off triggering the fault was the instinct that lead to the final test and ultimately the fix. Love not only the scope analysis, but the combination of skill sets that solved the problem. Ps I prefer breakout relays for any relay testing, but it was cool to know of a wire so fine that you can slip it into the terminals without opening them up when the relays inserted. I think that’s also a little bit of old school in there from Bernie! Lol! Nice!
Yes, knowing that the customer uses the AC was the turning point especially when the previous shop said the throttle defaulted all the time and he wasn't seeing it default initially.
@@abdul-kabiralegbe5660 I fix a lot of cars just by talking to the client. Freeze frame data helps a lot too, but this case that doesn't exist.
Ford normally puts their diodes in the fuse fox with the fuses I've replaced afew when people jumpstart the car backwards.. I see one for the PCM power but not the A/C clutch..
Back e.m.f. On any relay in all electronics is always needed You obviously no electronics which is needed to repair modern cars. I have put 4001 diodes on relays on old cars because customers said when going from hi beam to low a ticking sound came across on the radio. I love your vids great diagnostics.
Bernie you're a legend! Incredible documentaries of your findings.
Been nice to find the diode.
I have access to Ford Service Info and it too doesn't show the diode. Bet the coil has it right at the connector, or very close by.
Be neat to follow up on this car. Bet the coil is bad too.
Thanks Bernie.
Amazing work. Experience matters.. thanks for the videos
I have seen one amazing video with Keith and now Bernie. Keep them coming.
Cool case study Bernie! How exactly did the voltage spike on the load side of the AC clutch relay make it back to the PCM? We didn't see any evidence on the other channels of the scope 🤔
I wondered the same exact thing 🤷♂️
Ivan, I’m assuming inductance inside of the relay, high voltage on the load contacts carried over to control coil through inductance. My guess but I’m not sure I actually came here to ask the same question
@@joshwilson849 Yup that's what I was thinking... wish Bernie put his scope on the ECM control pin of the relay as well :)
@@PineHollowAutoDiagnostics or the high voltage reverse spike is going into the fuse box and making is way back to the PCM. The relay load and coil power feeds are connected together inside the fuse box even though they have separate fuses. Seen blower motor spinning down set SIR trouble codes due to back EMF.
How does this spike get its way to pcm ?
Is the diode in the fuse box?
Wish he was my teacher
Being that the battery is in the trunk, it may be more helpful to look at signals at the under hood main ground to understand what the module voltages are when the engine is running (powered by the alternator). Mainly for two reasons, the first is the long ground reference lead will pick up a considerable amount of noise, the second is we want to understand the I/O signals as close to the module connector as possible, which is under hood or near the firewall. Ideally, ground for troubleshooting a module would be directly at the module ground as a reference. This is important because what you can see is how the power and ground impedance relative to the battery in the trunk can be modulated by electrical overstress.
Great video as usual, so you set the diode up in reverse bias to absorb flyback because the grd potential would be higher + than the kickback? Is the kickback always negative value? Like the antenna instead of using multiple channels and multiple e-cops. Do you sell those? I had a Pico but now I'm spoiled rotten with the E-Scope and E-Scan. Thanks
So it can't be built this way or right off the bat this seems like to me it would be present off the showroom floor, but I thin, you are saying either the diode ground is lost or spikes over time make the ic sick enough to malfunction. That would necessarily necessitate a new computer which is only a partial solution for this Tbird. Have to be a big diode with high voltage and current capability.
Why didn't the AC compressor have a diode installed in the circuit to begin with. Normally these circuits do
Awesome case study, thank-you Mr. Thompson!
GREAT CONTENT!!!!
great video
Where do you get that information about how the tps code set and micro processor operates I would love to read that information so I can learn more
My guess is Bernie was once an engineer or knows people who are
The original relay had a built-in diode and the replacement does not.
WHAT MAKES THE SPIKE, THE RELAY OR THE COMPRESSOR CLUTCH.
Hey Bernie, what is the computer "gate" you are referring to in this video?
I believe he is referring to the transistor that controls the relay
@@joshwilson849 Thanks Josh. I always called those "drivers".