Those little connecting pins can cause lots of trouble when corrosion gets in. I used dielectric grease to prevent further trouble, just a little is needed.
You are referring to the bus bars between the pack's modules. That comes from there often being a little electrolyte seeping around the terminals of the modules as they get older. The seals there seep. This was theoretically corrected in later model Prius', but not very perfectly.
I took the battery control module off silver scare face Prius ,as I know that one was good and she ran fine .Then purchased another one for scar face Prius . Both going ok but slight clutch slip on blue one now .
FYI at minute 3: the white "thing" you found is the current sensor. There is never anything wrong with those. Just a coil of wire like in a transformer. The computer uses the magnetic field from the current flow as you drive to get an idea what the battery is up to. Also the large black box (min 1.39) is the pack contactor, a high voltage switch, it turns the pack on and off. There was no need to replace 99% of the parts you did!
@@thibautsoufflet44 I suspect the current sensor coil you replaced had a manufacturing defect that took some time to manifest itself. Either that or the pin connector for the current sensor had a little corrosion and was not making good contact until the sensor was taken out and replaced. If that was the case then there was probably nothing wrong with the old sensor, just a little corrosion in the connectors. Old Prius' have lots of weird corrosion issues as they get older! Look for water leaking in to the trunk too, these cars are notorious for that.
Hi you sound like you may know something that others don’t. I’ve fixed 2 Toyota Prius that had burned off the same pin that he found. I ended up putting a buy pass wire into the controller unit to fix. But I have a problem with my 2004 I had noticed that my HV indicator was running lower than normal for about a month then yesterday driving home The red triangle of death shows up. Battery indicator 1 bar but it flashed short time all green the back to 1 cooling fan turned one never did before I put a pre-filter on my intake when I got the car. So any way next morning I take HV cover off excepting to find low voltage every cell was at 7.4v . Can’t find any codes cleared start put foot on brake and drive put foot on gas to check charging battery very short time battery indicator on Display only showing 1 bar cooling fan turns on high go back ya batteries are hot and battery voltage is over 400v over my meter reading about a hour later. I went and checked the cell voltage 8.8v so it is just overcharging them and will not show on the dash. I’m baffled. If you can point me in a direction it would be appreciated. Thanks
@@alantierney1 It sounds like you messed up fixing the BCM computer pin that burned up. Or maybe the entire BCM computer is screwed in general and not telling the dash display the right data. I suggest you replace the BCM with a known good one.
I think my problem is worse though. I heard a gunshot while I was driving along. I'm sure one of the modules exploded. Time to pull the cover again. But your analysis of the potential problem was excellent. I have a question; Why does no one use dielectric grease to stop the corrosion on the pins?
@@cornishrob123 I found dielectric grease in the headlight jacks, but nowhere else. Strange that they failed to use it anywhere else. I think it's the best bet on keeping this corrosion under control. I don't have any handy and my car is dead in the driveway, but I may take it out and limp down to the store for some. Why Toyota and none of the repair efforts suggest it is another question for the sphinx. Is everyone nuts? Go down to a marine shop and it's a very common item. Marine items need much more protection. I had used No-Ox-Id on electrical work elsewhere but I don't know if that's the exact product in vogue these days. Thanks for your reply. Sorry I'm late. I'm not getting alerts these days. Not sure why.
Ok I had same triangle light on, also abs light on..and guess what the lousy negative battery cable bad connection where it mounts to car,I cleaned up, also bought 6 inch ground cable, went from battery to.cargo hook got good ground now all lights are off and runs like new
I'm leaving in south africa , I have a 2007 prius that has the red triangle of dead and the engine makes some noise when you start the car, I don't know how to fix this problem....I took the car to one of the toyota dealers, they told me that this is a difficult car and demand a lot of work, if you want yo fix it , it the same as buying a new car , so I'm stuck with the car at home. No where to get a new battery or even engine, the worse is there is no mecanics specialist of hybrid.... please help what should I do??
om namah shivayah, we bless your existence. I am an electrical engineer advanced power systems specialist. reply to my message and I will guide you as possible
I have seen that sort of pin corrosion on my 2002 Prius too. Poor connections in those sensor terminals can show up as a Master Battery error (aka red triangle of doom.) So I too cleaned up those pins and inside the connector socket too. They worked fine for some months, until the entire connector melted and burned up, ruining the computer and wiring harness! Those little wires are pack sensor wires. The voltage between each can be upwards a 200 or 300 VDC. So any amount of resistance there WILL create heat, promoting oxidation and the corrosion you found. So I have to warn everyone who finds this problem in their Prius' that it is really a BAD idea to "scratch around" on those pins. The problem you are creating is this: That pin coating is a thin gold plating (real gold!) and it is there to stop the brass pins under the gold from corroding. (gold never oxidizes, that is why it stays shiny forever) Scratching the gold will only accelerate the corrosion of the brass metal later on. Also cleaning the pins with a chemical can cause the same sort of problem. I do not have a good solution for you, aside from replacing the entire computer or HV battery! Maybe some sort of electrical paste? But I dread what else some goo could do in that socket! Toyota did not use anything other that the gold coating for corrosion resistance for a good reason. So be careful. I strongly suggest this guy takes apart those connectors and check to see if the corrosion is returning. "Nice to know" it can happen on a newer Prius' too? ;-)
Great! Caig makes a whole line of products to clean, lubricate, and coat terminals, pots, switches. It's what the pros in electronics use. Great for the bus bars and 56 nuts on the Prius main battery terminals ( on each module). Faster than using vinegar.
Don't know if you'll ever see this, but I've had the code P0AC0 coming off and on for about a month now and I have no idea what causes it. Sometimes I boot up the car, and there is no triangle and the car runs fine. Sometimes I boot up the car and there is the red triangle of doom along with the check engine light, and sometimes there is an added VSC light that comes on and I can't use cruise control. Tonight it was fine, yesterday I had lights. Any ideas? I am suspicious of it being the 12V, or perhaps the computer? Hybrid battery seems fine. Thanks for the vid, I'll be checking the ground/earth cable tomorrow. (Also, I have replaced the Hybrid battery in the prius twice by myself, but I have no idea how to mess the the computer and all those wires you replaced.)
Have your 12v battery load tested at a auto parts store too. This is often free. A weak 12v can cause all sorts of error codes. I also found this online: OBD Code P0AC0 - Hybrid Battery Pack Current Sensor "A" Circuit Range/Performance. The trouble code P0AC0 can be elucidated as Hybrid Battery Pack Current Sensor "A" Circuit Range/Performance. ... This sensor would inform the battery control module if the battery pack is being charged or discharged.
He did not need to replace most of those parts! The corroded terminals were the cause for sure. But read my write up above here about a warning for doing that too.
@@michael47lamb So my gut is pretty sure its a bad 12v, as it typically starts at 11.3v on on push start, and then rapidly declines when the lights are on. However, when the car is running, it stays at a consistent 13.9v. I've been suspicious of this batter for over a year now but have yet to replace it. Should I just bite the bullet and get a new one to at least take that out of the equation? Or should I look at the computer (which I know virtually nothing about)?
i've got red triangle from bad ground bolt ,sound like it's the end of the car ,even brake was gone. code was low voltage in traction control. scratching up and new bolt was enough. you need techstream and mini VCI cable to check
I get the red triangle when it rains, I did put silicone on the cracks but still it leaks in from somewhere else. My question is what actually shorts out when rain water gets in, where is that plug so I can clean it and put some grease to stop it in the future. Thanks
I have exactly the same issue with my prius. High Battery and when driving mis fires. How do I work it out, I am totally non technical person. You based in around London mate?
My catalyc comverter got stolen on my 2009 prius.. I drove like that for less than 2 miles and got red triangle with exclamation point on it. When that happened car started to loose power and eventually died on me:( right now I have it at a muffler shop where they will put another catalyc converter on but car still does not turn on..when I press on power button all the lights come on like if car it's on but engine not on. Lightss, radio and power windows work . The windows are slow though so I don't know if battery it's dying.
Check earth cable on aux battery in boot .Even get them to add another earth strap .She will need diagnostic to turn lights out if ran with no cat . Try that first an subscribe please.
Can I do that myself? This other guy told me to add a wire from 7.5A fuse to blue cable in fuse box and also to check my 12v and hybrid battery in the diagnostic prius screen.
Also should I pull a code on car to fund out exactly what's going on? My friend has a really expensive scan computer to pull codes. Should I do that too?
Those little connecting pins can cause lots of trouble when corrosion gets in.
I used dielectric grease to prevent further trouble, just a little is needed.
Thank You! this video is very useful.
Check moisture in the battery cooling fan. Located above the Aux battery.
There is always corrosion on the bars between each battery. Thanks for the video. Cheers.
You are referring to the bus bars between the pack's modules. That comes from there often being a little electrolyte seeping around the terminals of the modules as they get older. The seals there seep. This was theoretically corrected in later model Prius', but not very perfectly.
Use Caig Deoxit 5. Parts Express.
@@amazoidal Thank you very much for the tip.Cheers.
How is your Prius running? The triangle of doom has it came back since your video?
I took the battery control module off silver scare face Prius ,as I know that one was good and she ran fine .Then purchased another one for scar face Prius .
Both going ok but slight clutch slip on blue one now .
FYI at minute 3: the white "thing" you found is the current sensor. There is never anything wrong with those. Just a coil of wire like in a transformer. The computer uses the magnetic field from the current flow as you drive to get an idea what the battery is up to. Also the large black box (min 1.39) is the pack contactor, a high voltage switch, it turns the pack on and off.
There was no need to replace 99% of the parts you did!
Thanks so much for the information.
I had a P0a90 with P0ac1.
After lot of investigations the battery current sensor was the faulty part. Very rare maybe but not impossible.
@@thibautsoufflet44 I suspect the current sensor coil you replaced had a manufacturing defect that took some time to manifest itself. Either that or the pin connector for the current sensor had a little corrosion and was not making good contact until the sensor was taken out and replaced. If that was the case then there was probably nothing wrong with the old sensor, just a little corrosion in the connectors. Old Prius' have lots of weird corrosion issues as they get older! Look for water leaking in to the trunk too, these cars are notorious for that.
Hi you sound like you may know something that others don’t. I’ve fixed 2 Toyota Prius that had burned off the same pin that he found. I ended up putting a buy pass wire into the controller unit to fix. But I have a problem with my 2004 I had noticed that my HV indicator was running lower than normal for about a month then yesterday driving home The red triangle of death shows up. Battery indicator 1 bar but it flashed short time all green the back to 1 cooling fan turned one never did before I put a pre-filter on my intake when I got the car. So any way next morning I take HV cover off excepting to find low voltage every cell was at 7.4v . Can’t find any codes cleared start put foot on brake and drive put foot on gas to check charging battery very short time battery indicator on Display only showing 1 bar cooling fan turns on high go back ya batteries are hot and battery voltage is over 400v over my meter reading about a hour later. I went and checked the cell voltage 8.8v so it is just overcharging them and will not show on the dash. I’m baffled. If you can point me in a direction it would be appreciated. Thanks
@@alantierney1 It sounds like you messed up fixing the BCM computer pin that burned up. Or maybe the entire BCM computer is screwed in general and not telling the dash display the right data. I suggest you replace the BCM with a known good one.
I think my problem is worse though. I heard a gunshot while I was driving along. I'm sure one of the modules exploded. Time to pull the cover again. But your analysis of the potential problem was excellent. I have a question; Why does no one use dielectric grease to stop the corrosion on the pins?
Major issues are corrosion .saving expense, I have used WD40 and vasoline any thing has to be better .but petrol based lol possibly not the best .
@@cornishrob123 I found dielectric grease in the headlight jacks, but nowhere else. Strange that they failed to use it anywhere else. I think it's the best bet on keeping this corrosion under control. I don't have any handy and my car is dead in the driveway, but I may take it out and limp down to the store for some. Why Toyota and none of the repair efforts suggest it is another question for the sphinx. Is everyone nuts? Go down to a marine shop and it's a very common item. Marine items need much more protection. I had used No-Ox-Id on electrical work elsewhere but I don't know if that's the exact product in vogue these days.
Thanks for your reply. Sorry I'm late. I'm not getting alerts these days. Not sure why.
Ok I had same triangle light on, also abs light on..and guess what the lousy negative battery cable bad connection where it mounts to car,I cleaned up, also bought 6 inch ground cable, went from battery to.cargo hook got good ground now all lights are off and runs like new
Also reset key in hold start button about 50 seconds then stop and re start
Thats absolutely fantastic. So happy to help.
Can you show do a video of that! thanks!
Wow very good video we always learned hanks for your time
I'm leaving in south africa , I have a 2007 prius that has the red triangle of dead and the engine makes some noise when you start the car, I don't know how to fix this problem....I took the car to one of the toyota dealers, they told me that this is a difficult car and demand a lot of work, if you want yo fix it , it the same as buying a new car , so I'm stuck with the car at home. No where to get a new battery or even engine, the worse is there is no mecanics specialist of hybrid.... please help what should I do??
om namah shivayah, we bless your existence. I am an electrical engineer advanced power systems specialist. reply to my message and I will guide you as possible
I have seen that sort of pin corrosion on my 2002 Prius too. Poor connections in those sensor terminals can show up as a Master Battery error (aka red triangle of doom.) So I too cleaned up those pins and inside the connector socket too. They worked fine for some months, until the entire connector melted and burned up, ruining the computer and wiring harness!
Those little wires are pack sensor wires. The voltage between each can be upwards a 200 or 300 VDC. So any amount of resistance there WILL create heat, promoting oxidation and the corrosion you found.
So I have to warn everyone who finds this problem in their Prius' that it is really a BAD idea to "scratch around" on those pins. The problem you are creating is this: That pin coating is a thin gold plating (real gold!) and it is there to stop the brass pins under the gold from corroding. (gold never oxidizes, that is why it stays shiny forever) Scratching the gold will only accelerate the corrosion of the brass metal later on. Also cleaning the pins with a chemical can cause the same sort of problem.
I do not have a good solution for you, aside from replacing the entire computer or HV battery! Maybe some sort of electrical paste? But I dread what else some goo could do in that socket! Toyota did not use anything other that the gold coating for corrosion resistance for a good reason. So be careful.
I strongly suggest this guy takes apart those connectors and check to see if the corrosion is returning. "Nice to know" it can happen on a newer Prius' too? ;-)
Instead of using WD-40, use Caig Deoxit D5. It's made to clean terminals.
Cheers ,been looking for a spray to prevent corossion on connections, any ideas.
Great! Caig makes a whole line of products to clean, lubricate, and coat terminals, pots, switches. It's what the pros in electronics use. Great for the bus bars and 56 nuts on the Prius main battery terminals ( on each module). Faster than using vinegar.
Don't know if you'll ever see this, but I've had the code P0AC0 coming off and on for about a month now and I have no idea what causes it. Sometimes I boot up the car, and there is no triangle and the car runs fine. Sometimes I boot up the car and there is the red triangle of doom along with the check engine light, and sometimes there is an added VSC light that comes on and I can't use cruise control. Tonight it was fine, yesterday I had lights. Any ideas? I am suspicious of it being the 12V, or perhaps the computer? Hybrid battery seems fine. Thanks for the vid, I'll be checking the ground/earth cable tomorrow. (Also, I have replaced the Hybrid battery in the prius twice by myself, but I have no idea how to mess the the computer and all those wires you replaced.)
Why do think and say HV battery is ok ?
@@cornishrob123 because I replaced it this summer... Granted, it is a third part refurbished.
Have your 12v battery load tested at a auto parts store too. This is often free. A weak 12v can cause all sorts of error codes. I also found this online:
OBD Code P0AC0 - Hybrid Battery Pack Current Sensor "A" Circuit Range/Performance. The trouble code P0AC0 can be elucidated as Hybrid Battery Pack Current Sensor "A" Circuit Range/Performance. ... This sensor would inform the battery control module if the battery pack is being charged or discharged.
He did not need to replace most of those parts! The corroded terminals were the cause for sure. But read my write up above here about a warning for doing that too.
@@michael47lamb So my gut is pretty sure its a bad 12v, as it typically starts at 11.3v on on push start, and then rapidly declines when the lights are on. However, when the car is running, it stays at a consistent 13.9v. I've been suspicious of this batter for over a year now but have yet to replace it. Should I just bite the bullet and get a new one to at least take that out of the equation? Or should I look at the computer (which I know virtually nothing about)?
i've got red triangle from bad ground bolt ,sound like it's the end of the car ,even brake was gone. code was low voltage in traction control. scratching up and new bolt was enough. you need techstream and mini VCI cable to check
I get the red triangle when it rains, I did put silicone on the cracks but still it leaks in from somewhere else. My question is what actually shorts out when rain water gets in, where is that plug so I can clean it and put some grease to stop it in the future. Thanks
Also check under the tailgate ram.
@@cornishrob123 tailgate ram? In the uk we call it a boot haha
Many thanks you help me a lot ☺️👍👍👍👍👍👍
Thank you .Happy I could help you.
I have exactly the same issue with my prius. High Battery and when driving mis fires. How do I work it out, I am totally non technical person. You based in around London mate?
Plymouth I'm afffaid.
what were the codes before you started doing anything with the triangle?
Was coming up with high voltage battery pack failure.
@@cornishrob123 There had to have been a code that went with it. Was it a P0A80?
My catalyc comverter got stolen on my 2009 prius.. I drove like that for less than 2 miles and got red triangle with exclamation point on it. When that happened car started to loose power and eventually died on me:( right now I have it at a muffler shop where they will put another catalyc converter on but car still does not turn on..when I press on power button all the lights come on like if car it's on but engine not on. Lightss, radio and power windows work . The windows are slow though so I don't know if battery it's dying.
Check earth cable on aux battery in boot .Even get them to add another earth strap .She will need diagnostic to turn lights out if ran with no cat .
Try that first an subscribe please.
Can I do that myself? This other guy told me to add a wire from 7.5A fuse to blue cable in fuse box and also to check my 12v and hybrid battery in the diagnostic prius screen.
Also should I pull a code on car to fund out exactly what's going on? My friend has a really expensive scan computer to pull codes. Should I do that too?
I had the problem that i disconect the battery and when i connecte the Main battery forgot to push down.
Seriously I have done all the tests and it will only through the code about every 30 days...
Your high volts are my low volts