Same truck, batteries went dead with a diablo sport trinity tuner on it, replaced batteries and had gpcm comm loss, and a P02544. Aftermarket tuner would clear codes but they came back instantly, tried to restore original tune, but the ecm would not allow programming as the tuner lost the saved original back up and was detecting its own tune, therefore locked. Limped it to my local dealer where a low level tech owed me a favour, tried to flash/restore original tune, but no communication to ecm. Unplugged his tech 2 and truck would no longer communicate with my tuner! Now has no crank issue. Used those exact splice pack schematics to try disabling other modules interference with no luck. Planned on checking bus lines along fender well for wear as well as fuse block, and after seeing your video, i have high hopes!! Thank you so much for your great video!!
Thank you very much. Found that my ECM1 Fuse connection was the problem. Used a probe to crimp the connector for a tighter connection and just like that I was back running again.
Hello Phillip. Thanks for all your effort and time you put into your vids. After watching and listening to your tests, thoughts and reasoning in part 1 you had 2 options. Order another computer or start from the beginning, you chose correctly. Fixed with no unnecessary parts and only a few dollars to boot. I assume most guys (mechanics techs) would chose wrong. Thanks again
I watched both parts but it was demanding to get through part 1 so my brain is a little fried but not as bad as yours. The ECM does not ground one of its pins, STEP one on an ECM malfunction, test powers, and grounds. In part 2 here you said another tech tested powers, how did he miss this one pink wire, or with no load it tested fine with a multimeter which is a bad way to test wires as you know and this is the reason why you use the load pro. A couple days of work on your part just to find a bad power source which should have been found within the first hour of diagnosis. Thank you for the case study, this one gets highlighted in my LIBRARY so I don't make the same mistake, which I would not have made in the first place but I admit, you are a very good tech who just wanted to try a reprogramming?????? At least reprogramming a CLASSIC info will come in handy as for reprogramming I was thinking that the reflash for the EGR ought to have been done before the reprogram as the instructions seemed to state that an up-to-date ECM needs reprogramming, but I am really not sure, in the end, I can see the problem. Once again, AM crap installed being another problem.
Yes two other licenced techs checked powers and ground to this ECM prior to me getting it. I've started to rely more on using a headlight to load the circuit. The LoadPro is a great tool but really only pulls 500mA on the circuit which in my opinion is not enough. It also is not as visual as the headlight. Measuring voltage with a meter especially when the circuit is not loaded is inconclusive at best. Just did a Malibu Hybrid transmission power problem with a headlight and really worked just fine. ua-cam.com/video/0xxEaAGmCcc/v-deo.html
Are these wiring diagrams the same for 2005 chevy silverado 1500 5.3 Vortec? It's a basic work truck, no frills..manual locks , no power windows etc. I suspect damage in the pins of the lower left hand corner of the power distribution box. Relays were obviously heated near that area as there is heat evidence on them although they all still checked functional. I am having a no crank/no start symptom that started out intermittent that I could sometimes overcome by manipulating the gear stock but now there is no power to the ignition. PCM still seems to be communicating as there is still an engine light. The guy I bought the truck from was monkeying around trying to make trailer lights work at some point. I bought this truck second hand and he's obviously been in the steering column, probably disabling that stupid GM pass lock security crap ..no telling what I'll find. Also has symptom of possible BTSI wiring short. Fun times. Any help or insight is appreciated in advance if you have time.
The diesel and gas wiring is similar but not the same. The underhood fuse panels are notorious for internal corrosion and all kinds of electrical gremlins. Especially if the vehicle is exposed to road salt. If the no crank condition is as a result of the antitheft there should be codes related to that in the PCM and BCM. Do a network scan to start with. You can install a used fuse box as long as it's the same. A new one if needed is not that expensive but may be on back order. If you opt for the used one compare all pins are in the same places in both. Good luck.
Just curious Phillip. Who makes that relay test switch you're using to power up? Did you engineer that tech? I have a Lisle set but have never seen that particular one lol. Pretty neat.
I believe they are from Lisle but lost the box awhile ago. IPA makes a better set with a loop of wire for current ramping. www.grainger.ca/en/product/RELAY-BYPASS-SWITCH-KIT%2CHANDHELD%2C6-PCS-/p/WWG49ZT75
Hey, where can I get wiring diagrams like you have? I'm trying to track down a possible bad ground from my TCM for the same truck. 07 classic duramax. I've measured 57 ohms of resistance for both ground pins on tcm connector to multiple grounding points on truck so I would like to know where the wires go to be able to trace them and find any possible corrosion or grounding issues.
Diagrams are available through multiple sources but most are not free. Alldata, Mitchell and Identifix are some paid sources. I believe Alldata provides access for DIY owners for a specific fee. Like buying a service manual in the old days just electronic online. I'll look for a link and post it. That being said I could probably send you a diagram if you give me your email.
I have a 2007.5 duramax with code p0335. I replaced the sensor and checked the wires all the way back to the ecm. The wiring is good. The engine turns over but gets no signal from crankshaft. Any ideas on what to do? Truck was running when parked until I put a new used wiring harness on it. I put old harness on and still the same issue. I replaced harness originally because truck was throwing other codes caused by the original harness. The last time I drove the truck to where I parked it to work on it it had ran very rough. Leads me to think the reluctor wheel could have been loose and now has finally came loose or is to far to get a signal from the sensor. Any suggestions would be of help.
Ignition OFF and the scan tool disconnected for 90 seconds, disconnect the harness connector at the CKP sensor. Test for less than 5 ohms between low reference circuit terminal 2 of the connector and ground. ⇒X If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference 1 circuit terminal 3 of the connector and ground. If less than the specified range, test the 5-volt reference 1 circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM. If greater than the specified range, test the 5-volt reference 1 circuit for a short to voltage. If the circuit tests normal, replace the ECM. Test for 4.8-5.2 volts between the signal circuit terminal 1 of the connector and ground. If less than the specified range, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. Ignition OFF, connect a 3A fused jumper wire between signal circuit terminal 1 of the connector and ground. Ignition ON, observe the scan tool 5-Volt Reference 1 Circuit Status parameter. The parameter should display OK. ⇒X If the 5-Volt Reference 1 Circuit Status parameter does not display OK, test the signal circuit for a short to 5-volt reference. If the circuit tests normal, replace the ECM. Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal 1 of the connector. Connect the battery voltage supply to B+. Connect the black lead to ground. Set the J 38522 signal switch to 5 volts, the frequency to 5K, and the duty cycle to normal. Ignition ON, observe the CKP Sensor Signal Present parameter of the scan tool. The parameter should display YES. ⇒X If the parameter does not display YES, replace the ECM. If the circuits test normal replace the CKP sensor
I have a question I have 6.6 duramax van 2006 g3500 and my van will start in the morning but after an half hour of driving all my dash lights go hay wire and then back to normal sometimes stay off .. after I stop I have have to wait at least half hour before it will start also sometimes I turn it off my key domes out but van stays running…… help
@Phillip Bailey Does it seem strange i lost comm with my tuner and the no crank condition started only after trying the tech 2 reprogram? Thanks in advance (More info in previous comment)
When I put my key none of the dash lights come on except the security light and check engine light, it keeps saying code U0101 it’s a lbz 06 crank no start I’m stumped
I got mass air flow code all 7 injectors circuits are open except injector 2 glow plug module code injector cuircuit time bank 1 and 2 fuel injector group a and b supllly voyage circuit open I think it’s the ficm what’s your thought
@@zackwhite7120 you need a wiring diagram, test light and some probes. Try Alldatadiy.com for the diagram. There will be at least one power wire to the FICM and MAF. It should light a grounded test light. Look for the ground wires and test those with your test light connected to power. No power find the appropriate fuse and test it. No ground locate and repair ground. HTH
I have a 09 3500 6.6 it will not shut off by the key I have to pull the ecm fuse and replace it before I start it once I put fuse back in check engine light comes on even before I start truck
P2510 is an OBD-II generic code for the engine control module detecting the ignition relay is open or shorted causing the relay to not come on or turn off. Try removing the ignition relay. It's likely stuck on. If not may be a faulty ignition switch.
10-30-21 , I'm having same issue , 06 LBZ , cranks but won't start , bought this truck new in 06 and have had almost no trouble with this truck , all stock , this video is good info , hopefully it will help me get mine going , plenty of good clean fuel going to injector pump after installing lift pump , started right up and ran good for about 30 mins , cut it off , went to start it about an hour later now it won't start again , checked ECM 1 fuse and it's good , any help would be great , thanks
You need to scan the ecm for codes then look at Data to see what's missing. Do you have a crank signal, temp and baro readings correct then what kind if fuel pressure is tge hp pump making. Do you have injectors being commanded.
@@PhillipBailey hey Phillip thanks for responding , I don't have a scan tool , I checked all the ECM fuses , I found *3 fuse blown ,( fuel heater ) I replaced and tried again , still crank but no start , checked fuel delivery at Schaefer valve an still plenty of good clean fuel , I disconnect both batteries just in case something was locking me out , reconnected and tried again , cranks no start , I then cracked one of the lines loose at the injector , turn it over a minute and got no fuel , I'm missing something , what could stop fuel flow after the Schrader valve ,?? I have a hard time believing it's the injector pump or injectors , before I cut it off it has never smoked ( unless I would get down on it) never missed , loss power or anything ?? Question , how would I have gotten a p0088 high pressure code if there's no fuel on high pressure side ?? Does low pressure side require a certain pressure in order for the injector pump to start working ?? Obstruction in line somewhere maybe ??
@@douglasbaber4713 it was a no crank problem with no codes. The customer tried a different ECM but without an Antitheft relearn it would not crank anyways. I was originally called in to program the ECM but he didn't need one. The MIL would illuminate initially but then go out which is not correct. If you have a crank no start I don't think this is your problem. Need to scan and look at data.
@@douglasbaber4713 well you need to buy a decent scan tool first. Not just an OBD2 tool either. The Schrader valve is on the suction side of the HP pump so you won't get fuel here while cranking unless you have an aftermarket lift pump. NEVER Crack open a high pressure line fuel pressure can reach 25000 psi. As I said you need to look at data to see what kind of fuel pressure your making. Try priming it as opening the Schrader while cranking will introduce air in the system.
Pin 51 at C1 of the ECM is injector number 4 control and pin 40 of C1 is a 5 volt reference to the crank sensor. What's going on? Pin 51 which is circuit 844 travels through C108 Pin A4 is light blue/black and Pin 40 of C1 which is circuit 6270 is the 5 volt reference to the crank sensor travels through C107 pin B10 and is purple/white. Hope this helps...
@@PhillipBailey well my problem is the code P0090 gmc cierra 07 6.6 and already replaced the both sensor fuel pressure regulator on the fuel injection pump and the fuel real pressure sensor too but the check engine light is still on
@@franciscohunter4422 Well all that is left is wiring between the ECM and Fuel Pressure Regulator. The most common place for them to fail is at or near the two large connectors on the left valve cover. You need a good schematic and test the wires between the ECM and FPR. You will likely find a broken or corroded wire.
Same truck, batteries went dead with a diablo sport trinity tuner on it, replaced batteries and had gpcm comm loss, and a P02544. Aftermarket tuner would clear codes but they came back instantly, tried to restore original tune, but the ecm would not allow programming as the tuner lost the saved original back up and was detecting its own tune, therefore locked. Limped it to my local dealer where a low level tech owed me a favour, tried to flash/restore original tune, but no communication to ecm. Unplugged his tech 2 and truck would no longer communicate with my tuner!
Now has no crank issue. Used those exact splice pack schematics to try disabling other modules interference with no luck. Planned on checking bus lines along fender well for wear as well as fuse block, and after seeing your video, i have high hopes!! Thank you so much for your great video!!
Good luck let us know how you make out.
Thank you very much. Found that my ECM1 Fuse connection was the problem. Used a probe to crimp the connector for a tighter connection and just like that I was back running again.
I'm glad you figured it out.
Hello Phillip. Thanks for all your effort and time you put into your vids. After watching and listening to your tests, thoughts and reasoning in part 1 you had 2 options. Order another computer or start from the beginning, you chose correctly. Fixed with no unnecessary parts and only a few dollars to boot. I assume most guys (mechanics techs) would chose wrong. Thanks again
I watched both parts but it was demanding to get through part 1 so my brain is a little fried but not as bad as yours. The ECM does not ground one of its pins, STEP one on an ECM malfunction, test powers, and grounds. In part 2 here you said another tech tested powers, how did he miss this one pink wire, or with no load it tested fine with a multimeter which is a bad way to test wires as you know and this is the reason why you use the load pro. A couple days of work on your part just to find a bad power source which should have been found within the first hour of diagnosis. Thank you for the case study, this one gets highlighted in my LIBRARY so I don't make the same mistake, which I would not have made in the first place but I admit, you are a very good tech who just wanted to try a reprogramming?????? At least reprogramming a CLASSIC info will come in handy as for reprogramming I was thinking that the reflash for the EGR ought to have been done before the reprogram as the instructions seemed to state that an up-to-date ECM needs reprogramming, but I am really not sure, in the end, I can see the problem. Once again, AM crap installed being another problem.
Yes two other licenced techs checked powers and ground to this ECM prior to me getting it. I've started to rely more on using a headlight to load the circuit. The LoadPro is a great tool but really only pulls 500mA on the circuit which in my opinion is not enough. It also is not as visual as the headlight. Measuring voltage with a meter especially when the circuit is not loaded is inconclusive at best. Just did a Malibu Hybrid transmission power problem with a headlight and really worked just fine. ua-cam.com/video/0xxEaAGmCcc/v-deo.html
Are these wiring diagrams the same for 2005 chevy silverado 1500 5.3 Vortec? It's a basic work truck, no frills..manual locks , no power windows etc. I suspect damage in the pins of the lower left hand corner of the power distribution box. Relays were obviously heated near that area as there is heat evidence on them although they all still checked functional. I am having a no crank/no start symptom that started out intermittent that I could sometimes overcome by manipulating the gear stock but now there is no power to the ignition. PCM still seems to be communicating as there is still an engine light. The guy I bought the truck from was monkeying around trying to make trailer lights work at some point. I bought this truck second hand and he's obviously been in the steering column, probably disabling that stupid GM pass lock security crap ..no telling what I'll find. Also has symptom of possible BTSI wiring short. Fun times. Any help or insight is appreciated in advance if you have time.
The diesel and gas wiring is similar but not the same. The underhood fuse panels are notorious for internal corrosion and all kinds of electrical gremlins. Especially if the vehicle is exposed to road salt. If the no crank condition is as a result of the antitheft there should be codes related to that in the PCM and BCM. Do a network scan to start with. You can install a used fuse box as long as it's the same. A new one if needed is not that expensive but may be on back order. If you opt for the used one compare all pins are in the same places in both. Good luck.
Just curious Phillip. Who makes that relay test switch you're using to power up? Did you engineer that tech? I have a Lisle set but have never seen that particular one lol. Pretty neat.
I believe they are from Lisle but lost the box awhile ago. IPA makes a better set with a loop of wire for current ramping. www.grainger.ca/en/product/RELAY-BYPASS-SWITCH-KIT%2CHANDHELD%2C6-PCS-/p/WWG49ZT75
@@PhillipBailey thanks, I appreciate the information 😊
I finally found my problem 🤦🏽♂️🤦🏽♂️🤦🏽♂️🤦🏽♂️was not none of this but I did they this!!!!
Hey, where can I get wiring diagrams like you have? I'm trying to track down a possible bad ground from my TCM for the same truck. 07 classic duramax. I've measured 57 ohms of resistance for both ground pins on tcm connector to multiple grounding points on truck so I would like to know where the wires go to be able to trace them and find any possible corrosion or grounding issues.
Diagrams are available through multiple sources but most are not free. Alldata, Mitchell and Identifix are some paid sources. I believe Alldata provides access for DIY owners for a specific fee. Like buying a service manual in the old days just electronic online. I'll look for a link and post it. That being said I could probably send you a diagram if you give me your email.
www.alldatadiy.com/?gclid=Cj0KCQiAhs79BRD0ARIsAC6XpaXVZLtbzrsNIyMzKSaa1Q4TPbybr94jbBZmzg0RmjdXbQCAWOWPK5QaAihNEALw_wcB
I have a 2007.5 duramax with code p0335. I replaced the sensor and checked the wires all the way back to the ecm. The wiring is good. The engine turns over but gets no signal from crankshaft. Any ideas on what to do? Truck was running when parked until I put a new used wiring harness on it. I put old harness on and still the same issue. I replaced harness originally because truck was throwing other codes caused by the original harness. The last time I drove the truck to where I parked it to work on it it had ran very rough. Leads me to think the reluctor wheel could have been loose and now has finally came loose or is to far to get a signal from the sensor. Any suggestions would be of help.
Ignition OFF and the scan tool disconnected for 90 seconds, disconnect the harness connector at the CKP sensor.
Test for less than 5 ohms between low reference circuit terminal 2 of the connector and ground.
⇒X If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
Ignition ON, test for 4.8-5.2 volts between the 5-volt reference 1 circuit terminal 3 of the connector and ground.
If less than the specified range, test the 5-volt reference 1 circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
If greater than the specified range, test the 5-volt reference 1 circuit for a short to voltage. If the circuit tests normal, replace the ECM.
Test for 4.8-5.2 volts between the signal circuit terminal 1 of the connector and ground.
If less than the specified range, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
Ignition OFF, connect a 3A fused jumper wire between signal circuit terminal 1 of the connector and ground.
Ignition ON, observe the scan tool 5-Volt Reference 1 Circuit Status parameter. The parameter should display OK.
⇒X If the 5-Volt Reference 1 Circuit Status parameter does not display OK, test the signal circuit for a short to 5-volt reference. If the circuit tests normal, replace the ECM.
Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal 1 of the connector. Connect the battery voltage supply to B+. Connect the black lead to ground.
Set the J 38522 signal switch to 5 volts, the frequency to 5K, and the duty cycle to normal.
Ignition ON, observe the CKP Sensor Signal Present parameter of the scan tool. The parameter should display YES.
⇒X If the parameter does not display YES, replace the ECM.
If the circuits test normal replace the CKP sensor
Check the circuits to the crank sensor, 5 volt reference, signal and ground. I doubt its the reluctor.
Can I give you a call sometime to ask you some questions?
@@tuckermelton7446 807 626 3683
I have a question
I have 6.6 duramax van 2006 g3500 and my van will start in the morning but after an half hour of driving all my dash lights go hay wire and then back to normal sometimes stay off .. after I stop I have have to wait at least half hour before it will start also sometimes I turn it off my key domes out but van stays running…… help
Did you get it fixed I’m having issues like that
Can you explain what the arrow and x means?
Not sure what you're referring to
@Phillip Bailey
Does it seem strange i lost comm with my tuner and the no crank condition started only after trying the tech 2 reprogram? Thanks in advance
(More info in previous comment)
The tech2 may have erased the original tune and bricked the module. Some of those aftermarket tuners lock the module to prevent further tuning.
When I put my key none of the dash lights come on except the security light and check engine light, it keeps saying code U0101 it’s a lbz 06 crank no start I’m stumped
You need to do a network scan of all controllers for codes. Take note of which controllers talk and which don't. You likely a network problem
I got mass air flow code all 7 injectors circuits are open except injector 2 glow plug module code injector cuircuit time bank 1 and 2 fuel injector group a and b supllly voyage circuit open I think it’s the ficm what’s your thought
Check powers and grounds to the MAF and FICM first.
@@PhillipBailey where do I check the powers and grounds ?
@@zackwhite7120 you need a wiring diagram, test light and some probes. Try Alldatadiy.com for the diagram. There will be at least one power wire to the FICM and MAF. It should light a grounded test light. Look for the ground wires and test those with your test light connected to power. No power find the appropriate fuse and test it. No ground locate and repair ground. HTH
@@PhillipBailey so similar to what you did in your vid ?
@@zackwhite7120 yes but test at the FICM and MAF sensor
I have a 09 3500 6.6 it will not shut off by the key I have to pull the ecm fuse and replace it before I start it once I put fuse back in check engine light comes on even before I start truck
P2510 is an OBD-II generic code for the engine control module detecting the ignition relay is open or shorted causing the relay to not come on or turn off. Try removing the ignition relay. It's likely stuck on. If not may be a faulty ignition switch.
10-30-21 , I'm having same issue , 06 LBZ , cranks but won't start , bought this truck new in 06 and have had almost no trouble with this truck , all stock , this video is good info , hopefully it will help me get mine going , plenty of good clean fuel going to injector pump after installing lift pump , started right up and ran good for about 30 mins , cut it off , went to start it about an hour later now it won't start again , checked ECM 1 fuse and it's good , any help would be great , thanks
You need to scan the ecm for codes then look at Data to see what's missing. Do you have a crank signal, temp and baro readings correct then what kind if fuel pressure is tge hp pump making. Do you have injectors being commanded.
@@PhillipBailey hey Phillip thanks for responding , I don't have a scan tool , I checked all the ECM fuses , I found *3 fuse blown ,( fuel heater ) I replaced and tried again , still crank but no start , checked fuel delivery at Schaefer valve an still plenty of good clean fuel , I disconnect both batteries just in case something was locking me out , reconnected and tried again , cranks no start , I then cracked one of the lines loose at the injector , turn it over a minute and got no fuel , I'm missing something , what could stop fuel flow after the Schrader valve ,?? I have a hard time believing it's the injector pump or injectors , before I cut it off it has never smoked ( unless I would get down on it) never missed , loss power or anything ?? Question , how would I have gotten a p0088 high pressure code if there's no fuel on high pressure side ?? Does low pressure side require a certain pressure in order for the injector pump to start working ?? Obstruction in line somewhere maybe ??
When you were having trouble and found the broken wire on ECM 1 fuse , were you having a no crank problem , or crank and no start problem ??
@@douglasbaber4713 it was a no crank problem with no codes. The customer tried a different ECM but without an Antitheft relearn it would not crank anyways. I was originally called in to program the ECM but he didn't need one. The MIL would illuminate initially but then go out which is not correct. If you have a crank no start I don't think this is your problem. Need to scan and look at data.
@@douglasbaber4713 well you need to buy a decent scan tool first. Not just an OBD2 tool either. The Schrader valve is on the suction side of the HP pump so you won't get fuel here while cranking unless you have an aftermarket lift pump. NEVER Crack open a high pressure line fuel pressure can reach 25000 psi. As I said you need to look at data to see what kind of fuel pressure your making. Try priming it as opening the Schrader while cranking will introduce air in the system.
Having same problem with 2009 GMC Sierra 2500 🤦🏽♂️🤦🏽♂️🤦🏽♂️🤦🏽♂️🤦🏽♂️
P0612 truck won’t start I need all the help
Is your truck the classic 06 or 08 style? If the 08 style likely a failed fuse box.
@@PhillipBailey 04 lb7 I did change the fuse box before this started
Truck was running for two weeks with different box
Hey hi brother I’m looking for the pin 51 and 40 for the 07 gmc 2500 6.6 liter diesel truck
What would you like to know about them? I'll try to help as much as I can...
Pin 51 at C1 of the ECM is injector number 4 control and pin 40 of C1 is a 5 volt reference to the crank sensor. What's going on?
Pin 51 which is circuit 844 travels through C108 Pin A4 is light blue/black and Pin 40 of C1 which is circuit 6270 is the 5 volt reference to the crank sensor travels through C107 pin B10 and is purple/white. Hope this helps...
@@PhillipBailey well my problem is the code P0090 gmc cierra 07 6.6 and already replaced the both sensor fuel pressure regulator on the fuel injection pump and the fuel real pressure sensor too but the check engine light is still on
@@PhillipBailey I know I very appreciate you brother
@@franciscohunter4422 Well all that is left is wiring between the ECM and Fuel Pressure Regulator. The most common place for them to fail is at or near the two large connectors on the left valve cover. You need a good schematic and test the wires between the ECM and FPR. You will likely find a broken or corroded wire.
Can you help me with that please
P2510 is the code
Could be tge ECM power relay is stuck on. Don't remember if it's called ECM or ignition relay.