Why am I burning up BCM's?

2010 dbl cab 4wd with 75,000 miles. About a month ago I noticed my key fob not working. Around the same time a few dash lights and rear tailights also quit. I took it to my local Toy dealer who was sure they were not related, but said the truck would not take a program and it was not the fob.

I took it to my shop that works on my race car and though they claim to have had their Toyota master tech work on it, after 2 weeks and 3 burned up BCM's and them removing all my aftermarket items (piaa lights/hid's/aux gauges) the truck still burned up the 3rd BCM, so they threw their hands up and suggested I take it back to the Toy dealer.

Toy dealer has had it a day and replaced the battery I bought from them 8 months ago and says that didn't correct the problem so he will keep looking, but it could get expensive as these BCM's run about $550 a shot.

Any ideas on this? I'm supposed to move this week and need this thing fixed!!!

 

What is a BCM?

 

Sounds to me like you have shorted wire accidently powering 12 volts to an unprotected wire in the engine immobiliser circuit
Engine Immobiliser
Engine Immobiliser System: Parts Location, System Diagram
Engine Immobiliser System: System Description, How To Proceed With Troubleshooting
Engine Immobiliser System: Registration
Engine Immobiliser System: Problem Symptoms Table, Terminals Of ECU
Engine Immobiliser System: Diagnosis System, DTC Check / Clear
Engine Immobiliser System: Data List / Active Test
Engine Immobiliser System: Diagnostic Trouble Code Chart, B2780
Engine Immobiliser System: B2784
Engine Immobiliser System: B2793, B2794
Engine Immobiliser System: B2795, B2796, B2798
Engine Immobiliser System: B2797
Engine Immobiliser System: B2799
Engine Immobiliser System: ECU Power Source Circuit

 

Body Control Module. The computer for the body.

OP, I would check connections at the BCM, and follow ALL of the grounds and verify that they are solid and clean. A bad ground can cause a computer to head south fast.

 

Thanks BamaToy

 

I've had a couple of similar issues with my corvette and they are way touchy on electrical issues and bad grounds. I'm almost down to my bicycle at this point.

My concerns that some of these techs don't know enough to check what needs checked and rack up a bill before they even have looked at what they should.

Charging me $350 for changing out the battery when it took me less than 45 minutes to do that in their parking lot when I bought their Toyota battery 8 months ago. THAT kind of stuff really pisses me off!!!

 

A person has to be very careful with aftermarket items, I would check & make sure things are returned to stock, I have found many "tech's" use shortcuts, I've had that happen. jmop

 

Was that $350 including the battery? If so, then what was the price of the battery itself?

 

That is why I was asking. It seemed a bit much of a quote, even from a dealer. Was curious the breakdown in the pricing there.

 

Well apparently after I left the service advisor a message that I had purchased the battery there and changed it out in his parking lot in 15 minutes he told they had replaced the battery at no charge to me. I can afford that.

At the same time, he says his tech really has no idea where to go from here with figuring out the problem, other than starting with new OEM tailights. The other shop installed the wrong style (non led) in an effort to get rid of the aftermarket ones that were on the truck when I bought it.

I guess I'm going to be taking it to an auto electric specialist today with the hope he can figure it out???

 

Did you ever figure out your issue?

 

Well here is what I did figure out...the auto elec specialist checked it out and threw up his hands as he could not figure it out either. The shop that works on my vette installed a new TRD 7 pin trailer harness and said they cleaned everything up there and it was good. Then it blew another BCM. I had the previous one replaced under warranty and also got new led stock style tailights, though they were not from Toyota, which saved me $250. I then went to my trailer repair man and when he got under the truck to look at the 7 pin harnness, he called me over. The vette shop had NOT cleaned things up, but had just attached to the wiring conglomeration that was under there, despite the workman telling me he had taken it all out and just wired in the new 7 pin connector.

So once that was done properly I've not blown another BCM, but a year or so later when hooking up a boat that has electric brakes we discovered that one of the 7 pin connectors is just for that, with a hot lead that when in reverse will make sure your brakes don't engage when backing up an incline. Mine were not working and when I traced it down to the back of the 7 pin I had no power, and followed it to the BCM where it also appears to be dead. I tapped into the backup light wire and had to put another lead out to the end of the 7 pin that looks goofy but when clipped into a lead on the correct boat harness will release the brakes, so I haven't got it all figured out, but I'm not blowing a $500 BCM all the time and I've just decided to live with the hot wire tucked in behind the license plate until I need it.

 

I had a similar problem on my vette, bad ground. Gotta get crazy and really get into checking the wiring! It took me over a week (few hours) each day to find mine. Best suggestion scope camera to check in those hard to see dark areas with a light on it.

 

I see that this is old also I admit that I do not have a Toyota either but you are talking about the same issue that I am experiencing , so I wanted to ask did any of you ever figure out why it was burning?