Weird electrical issue on 2015 Trail
- Thread starter Ezekiel2222
- Start date
Ezekiel2222
New member
They didn't really "tap" into any circuit. If you follow the link to my other post, you will see that these were factory Toyota heated seats that I had installed. They literally unplugged the old seat wiring harness, plugged in the new one, and everything worked. No splicing, soldering, creating new wires, ect. Given they are factory Toyota seat heaters, I would assume they pull exactly as much power as they need to.
No deep puddles that I can think of, but this is Colorado in the winter, and unfortunately my vehicle is stuck outside while the wife gets the garage
No deep puddles that I can think of, but this is Colorado in the winter, and unfortunately my vehicle is stuck outside while the wife gets the garage
Jernik
New member
Couple of things come to mind on this, unfortunately I don't think it will help the OP much.
1) If heated seats are the cause of this issue, then how is this company being referred by the Dealership, and why are they still doing these installations? Seems to me if the seats truly were the issue, many trucks would be coming back with problems.
2) If regular Trail BCM's are incapable of handling heated seats, why would the factory use the same wiring harness used for Trail Premium AND hook up the offending wires/circuits to a BCM that can't handle those extra loads?
Good luck.
1) If heated seats are the cause of this issue, then how is this company being referred by the Dealership, and why are they still doing these installations? Seems to me if the seats truly were the issue, many trucks would be coming back with problems.
2) If regular Trail BCM's are incapable of handling heated seats, why would the factory use the same wiring harness used for Trail Premium AND hook up the offending wires/circuits to a BCM that can't handle those extra loads?
Good luck.
Jernik
New member
One more thought from deep left field... Is it possible the battery is bad? I know it's a new truck, and I only bring this up on the recollection of a Dakota my dad had. It started doing weird things when the battery started getting older/weak. Once he replaced the battery, all was fine again. Yours was fine for a month, maybe it is weak/defective and the colder weather is pushing it to fail? I dunno, just a thought.
gm350reratliff
New member
They didn't really "tap" into any circuit. If you follow the link to my other post, you will see that these were factory Toyota heated seats that I had installed. They literally unplugged the old seat wiring harness, plugged in the new one, and everything worked. No splicing, soldering, creating new wires, ect. Given they are factory Toyota seat heaters, I would assume they pull exactly as much power as they need to.
No deep puddles that I can think of, but this is Colorado in the winter, and unfortunately my vehicle is stuck outside while the wife gets the garage
Ok, I remember that thread. Sure enough, plug and play. Now I really don't believe the dealers assessment. The heaters would've worked or not. Clearly they did. I would have to look at a diagram but I would bet money the BCM does not supply the power for the bun warmers. Power would come from a fuse and possibly through a relay, in which the BCM merely controls. I'm now leaning toward a faulty BCM (not bun warmer related), a bad wiring harness or a bad ground causing your troubles.
Ezekiel2222
New member
That was my thought exactly. Clearly the BCM contained the necessary circuitry to allow the seat heaters to function for a month, including the variable temperature control and everything, so it's a little odd to say that it "doesn't support them".
I believe they think the BCM may be the problem because of all the other weird lights/locks/alarms that aren't working right, and AFAIK those are all controlled by the same BCM??? Also, based on what the service manager told me, the seat wiring harness plugs into the "under-floor" harness, which in turn plugs into the BCM, so clearly the seat heaters interact with it at some level. I don't know much about the BCM, but it seems to be some sort of computer/relay module that is part of the fuse box and controls and the various electrical doodads on the vehicle.
I believe they think the BCM may be the problem because of all the other weird lights/locks/alarms that aren't working right, and AFAIK those are all controlled by the same BCM??? Also, based on what the service manager told me, the seat wiring harness plugs into the "under-floor" harness, which in turn plugs into the BCM, so clearly the seat heaters interact with it at some level. I don't know much about the BCM, but it seems to be some sort of computer/relay module that is part of the fuse box and controls and the various electrical doodads on the vehicle.
wfo9
New member
Sorry to hear, this. I kind of figured you would end up here. Are they trying to make you pay for the BCM and work...?
I would be really surprised if they had different physical BCMs per model. That is just too expensive to mfg. They usually just have different software, but I'm not sure how Toyota does it.
These are some common Acronyms used:
BCM = Body Control Module
PCM = Powertrain Control Module
TCM = Transmission Control Module
ECU = Engine Control Unit
ECM = Engine Control Module
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philsey
New member
This is no help, but I have to wonder: if these are OEM Toyota seats, and simply plug and play, why your dealer farmed this out to a third party?
Did the dealer provide the part numbers? Did you buy them from him?
wfo9
New member
I'm sure it was just the heating element put into his factory seats. It's nothing complicated.
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Saker
Senior Member
I was thinking the same thing.
Did the dealer look up the heaters/seats for your particular model?
If he had a listing for them for that year and model, without any further details about the BCM not being compatible, then, them not being compatible should not be an issue.
Maybe it is a faulty BCM, period!
Now, if the dealer just looked up the part #s for the heaters/seats and said...this will work, how were you to know that they would not.
Still points back to the dealership. IMHO
FrontRange4Runner
New member
I was gonna say the same thing. This happened on my Subaru. All kinds of crazy electrical issues would pop up, and then disappear. Eventually I realized my battery terminal was loose. As soon as it was tight, the issues went away and never came back. I felt like a moron for driving around for so long without checking something so simple... :rockthrow:
Ezekiel2222
New member
I can't really blame the dealer for the heated seats:
When I bought the vehicle I asked my sales rep about getting heated seats installed. He said they could do it, but he was also honest and told me that they just farm it out to a car audio place down the street, and he told me it would be cheaper for me to go there myself.
So needless to say I took his advice and went there on my own. When the audio shop told me they just install cheap aftermarket heaters I decided to research what it would take to get the OEM parts installed. A few posts on this forum later and I had ordered the parts myself and took them back to the audio shop to be installed.
In hindsight maybe I should have involved the dealer in the install process, so it would be "covered", but I'm not sure if they would have helped or not. Anyway, it is what it is, and now I'm just doing my best to get this problem resolved.
When I bought the vehicle I asked my sales rep about getting heated seats installed. He said they could do it, but he was also honest and told me that they just farm it out to a car audio place down the street, and he told me it would be cheaper for me to go there myself.
So needless to say I took his advice and went there on my own. When the audio shop told me they just install cheap aftermarket heaters I decided to research what it would take to get the OEM parts installed. A few posts on this forum later and I had ordered the parts myself and took them back to the audio shop to be installed.
In hindsight maybe I should have involved the dealer in the install process, so it would be "covered", but I'm not sure if they would have helped or not. Anyway, it is what it is, and now I'm just doing my best to get this problem resolved.
wfo9
New member
[MENTION=115178]Ezekiel2222[/MENTION]
Did they provide you with any conformation that the BCM you have does not support heated seats?
Hey [MENTION=66389]BlackWorksInc[/MENTION],
Don't mean to put you on the spot, but does this sound legit to you.
Do the different models have different physical BCMs?
They are basically telling him that he fried the BCM (after a few months) by plugging factory seat heaters into the factory under-seat harness. Because the BCM part# is different and not properly equipped to deal with heated seats.
Sounds a little fishy to me.
Did they provide you with any conformation that the BCM you have does not support heated seats?
Hey [MENTION=66389]BlackWorksInc[/MENTION],
Don't mean to put you on the spot, but does this sound legit to you.
Do the different models have different physical BCMs?
They are basically telling him that he fried the BCM (after a few months) by plugging factory seat heaters into the factory under-seat harness. Because the BCM part# is different and not properly equipped to deal with heated seats.
Sounds a little fishy to me.
Cheers!
Member
If the seat heaters take too much current and cause the voltage to sag to an electronics module, I guess it could happen.
Electronics needs to maintain a certain high and low voltage. If it isn't in the range (high, over voltage... if there was protection, gets tripped and if there is none components burn up... if it goes under weird symptoms can happen).
However I would like to think that the fuse is sized correctly for the circuit that the BCM is on, such that if there is that much voltage sag, the current draw would be much greater than the allowed for the circuit and the fuse or breaker would trip. But you never know until you put a an Ammeter or voltmeter on and watch.
Personally I'm always on the fence of modding a car with bumper to bumper warranty. I usually have no reservations for a car out of warranty to modify it, but since I paid for the warranty (which is usually accounted on the books by manufacturers to be 5 to 7%) of the manufacturing cost of a product. I'd like to be able to take advantage of it when and if the time comes. Nothing is ever made perfect. There is always very slight variations that are hopefully inside of tolerances.
Electronics needs to maintain a certain high and low voltage. If it isn't in the range (high, over voltage... if there was protection, gets tripped and if there is none components burn up... if it goes under weird symptoms can happen).
However I would like to think that the fuse is sized correctly for the circuit that the BCM is on, such that if there is that much voltage sag, the current draw would be much greater than the allowed for the circuit and the fuse or breaker would trip. But you never know until you put a an Ammeter or voltmeter on and watch.
Personally I'm always on the fence of modding a car with bumper to bumper warranty. I usually have no reservations for a car out of warranty to modify it, but since I paid for the warranty (which is usually accounted on the books by manufacturers to be 5 to 7%) of the manufacturing cost of a product. I'd like to be able to take advantage of it when and if the time comes. Nothing is ever made perfect. There is always very slight variations that are hopefully inside of tolerances.
BlackWorksInc
New member
I'll have to look into it further myself, but to be perfectly honest there may be some truth to what the dealership is saying.
Toyota unlike some manufactuers is extremely tyranical when it comes to their software. There are barely a handful of modules you can actually reprogram with a scantool (BCM is not one in most vehicles) and so while the physical computer looks almost identical, the only difference may be software (an example is the multitude of different part numbers for Skid Control ECUs on Master Cylinder Assemblies, despite the unit being physically the same in the '06~'15 4Runner, '10+ Tacoma, '07~'14 FJ Cruiser, and '06+ GX460/470)
Again, I'll have to dig a little deeper; but chances are even the "Toyota Engineers" will probably not have a damn idea. I am finding more and more that TAS is often less knowledgable about Toyota components than most technicans (perhaps this is a result of many of the Older more Experienced guys quitting instead of moving to Texas?)
wfo9
New member
Wow, Toyota is a strange bird when it comes to electronics.
I can't imagine the BCM not being field programmable, but they do tend to do things differently than everyone else.
That is probably the thing I like least about Toyota and it is the reason there is such limited aftermarket support for things like power adders... Not really good vehicles to modify, but I would have thought seat heaters would be easy.
Lesson learned (I guess).
I can't imagine the BCM not being field programmable, but they do tend to do things differently than everyone else.
That is probably the thing I like least about Toyota and it is the reason there is such limited aftermarket support for things like power adders... Not really good vehicles to modify, but I would have thought seat heaters would be easy.
Lesson learned (I guess).
BlackWorksInc
New member
[MENTION=115178]Ezekiel2222[/MENTION]
So looking the diagrams over a bit it seems like there's two distinct systems in terms of Heated Seats. The first is "Climate Controlled Seats" which is both heated & cooled and is actually tied into the A/C Amplifier module, the second is "Heated Seats" which is what you appear to have. With Heated seats the units are self-contained with their own control units mounted to the underside of the seat, they get power from the 20amp S/HTR FR & 10amp ECU Ign No.2 fuses.
The only tie they have into any other system is through the J/B (Junction Block) No.5 (this seems to be a common Ignition Power Source for multiple areas/Modules of the vehicle) and J/B F64 (this seems to be a common ground source for many of the same modules J/B No.5 supplies.)
Ironically enough I do not see the Main Body BCM to be on either of the Junction Blocks, but the Combination Meter as well as the Smart Key System, Clock, Tail Gate ECU, ABS, 4WD, ect. are all shared between these junction blocks. Though I find it hard to believe that the Seat Heater Controllers took out multiple modules on Junction Block No.5 because its a 10amp fused common power source which theoretically should have fried the other modules if the fuse somehow failed to open; both Junction blocks appear to be more for powering up modules than doing actual labor (i.e. operating solenoids, heater elements, actuators, ect.) Even the controllers are tapping into the 20amp fuse for their actual work current, while the 10amp power supply is strictly to operate the logic circuits of the modules.
The issue you're describing, combined with the lack of module communication (based on what the technician stated before, though as I said earlier it sounded a bit odd to me with how you repeated it) makes me think the issue is either on the CAN/Multiplex communication bus and/or an issue with an overall power supply/ground issue that is most likely not tied to the seat heaters (at least I can't see how they tie beyond using the same 10amp computer power supply and ground junction block that over a dozen other modules use) being installed.
Note- J/B No.5 is the large grey block that the 10amp ECU No.2 Fuse feeds into, J/B F64 is the small box on the ground wire in the center bottom of the diagram (I would have colored them in, but I do not have a .pdf editing program
)
View attachment Overall EWD Heated Seats '15 T4 TE.pdf
So looking the diagrams over a bit it seems like there's two distinct systems in terms of Heated Seats. The first is "Climate Controlled Seats" which is both heated & cooled and is actually tied into the A/C Amplifier module, the second is "Heated Seats" which is what you appear to have. With Heated seats the units are self-contained with their own control units mounted to the underside of the seat, they get power from the 20amp S/HTR FR & 10amp ECU Ign No.2 fuses.
The only tie they have into any other system is through the J/B (Junction Block) No.5 (this seems to be a common Ignition Power Source for multiple areas/Modules of the vehicle) and J/B F64 (this seems to be a common ground source for many of the same modules J/B No.5 supplies.)
Ironically enough I do not see the Main Body BCM to be on either of the Junction Blocks, but the Combination Meter as well as the Smart Key System, Clock, Tail Gate ECU, ABS, 4WD, ect. are all shared between these junction blocks. Though I find it hard to believe that the Seat Heater Controllers took out multiple modules on Junction Block No.5 because its a 10amp fused common power source which theoretically should have fried the other modules if the fuse somehow failed to open; both Junction blocks appear to be more for powering up modules than doing actual labor (i.e. operating solenoids, heater elements, actuators, ect.) Even the controllers are tapping into the 20amp fuse for their actual work current, while the 10amp power supply is strictly to operate the logic circuits of the modules.
The issue you're describing, combined with the lack of module communication (based on what the technician stated before, though as I said earlier it sounded a bit odd to me with how you repeated it) makes me think the issue is either on the CAN/Multiplex communication bus and/or an issue with an overall power supply/ground issue that is most likely not tied to the seat heaters (at least I can't see how they tie beyond using the same 10amp computer power supply and ground junction block that over a dozen other modules use) being installed.
Note- J/B No.5 is the large grey block that the 10amp ECU No.2 Fuse feeds into, J/B F64 is the small box on the ground wire in the center bottom of the diagram (I would have colored them in, but I do not have a .pdf editing program
)View attachment Overall EWD Heated Seats '15 T4 TE.pdf
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Ezekiel2222
New member
Spoke with my service rep today. The "Toyota Engineers" have not got back to them yet, so he didn't have any answers for me, but he did have the part numbers:
89220-35340
89220-35250
He didn't know which was which, but luckily I have the internet! According to this site the first one is for a Trail, and the second one is actually for the Limited Package. That site does not specifically list a part for the Trail Premium, so it is possible it uses the same part as the Limited. Either way, at least now I have a price point, if they ever get an answer from the engineers.
I'm almost inclined to print out BlackWorksInc's post and take it in to the dealership, but I'm not sure they would have any idea what it all means
89220-35340
89220-35250
He didn't know which was which, but luckily I have the internet! According to this site the first one is for a Trail, and the second one is actually for the Limited Package. That site does not specifically list a part for the Trail Premium, so it is possible it uses the same part as the Limited. Either way, at least now I have a price point, if they ever get an answer from the engineers.
I'm almost inclined to print out BlackWorksInc's post and take it in to the dealership, but I'm not sure they would have any idea what it all means
BlackWorksInc
New member
Spoke with my service rep today. The "Toyota Engineers" have not got back to them yet, so he didn't have any answers for me, but he did have the part numbers:
89220-35340
89220-35250
He didn't know which was which, but luckily I have the internet! According to this site the first one is for a Trail, and the second one is actually for the Limited Package. That site does not specifically list a part for the Trail Premium, so it is possible it uses the same part as the Limited. Either way, at least now I have a price point, if they ever get an answer from the engineers.
I'm almost inclined to print out BlackWorksInc's post and take it in to the dealership, but I'm not sure they would have any idea what it all means
You're more than welcome to if you want? I mean its not like it will help them in their diagnostics too much more than where they are. But I guess it helps you point out the unlikelihood that the seat heaters caused the failure of the BCM directly.
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