BCM keeps burning up and taking the tailights, parking lights and key fob out

Tiny
DANBSHERWOOD
  • MEMBER
  • 2010 TOYOTA TACOMA
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 73,000 MILES
Noticed the key fob and various dash lights not working about a month ago. Took it to the Toyota dealer and they said it was not the fob (I already replaced the batteries), but the truck would not program. Took it to another shop who disconnected the aftermarket parts (trailer 7 pin harness-piaa lights-tailgate lock-gauges-trailer brake and tailights assemblies, thinking these were the culprit. Nope, burn up another BCM. They put another one in (3rd) and it worked for several hours until they plugged the ac "magnifier" back in and burned that BCM up. They told me to take it back to the Toyota dealer.

The Toyota dealer looked at it and said I need to put in new OEM tailights to replace the non led ones the other shop put in and put in a new BCM and then do an ohm test on every single wire until the BCM burned up. I then took it to an auto elec specialist who said his equipment couldnt communicate with the BCM, which I've learned wont communicate with anything, MIT either works or. Burns up at $550 a pop.

So I've hooked back up the piaa lights because the headlights they are hooked to have always worked. I've hooked back up the gauges as they still work plugged into the obd port. The key fob still does to work as well as various dash lights (ac control lights/radio buttons) and park lights, but brake lights do.

I've bought new led tailights and a new BCM. What else should I do to fix this dang thing before installing and possibly burning up this new BCM?
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Tuesday, September 30th, 2014 AT 11:02 PM

8 Replies

Tiny
DANBSHERWOOD
  • MEMBER
To clarify. The parking lights, tailights, key fob, hazard flashers and various dash lights (ac controls and radio buttons) still do NOT work. I will install the new OEM style led tailights, but hesitant to install the new $500 BCM I have just to see it burn up without having any other ideas on how to solve this. HELP!
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Tuesday, September 30th, 2014 AT 11:15 PM
Tiny
HMAC300
  • EXPERT
Realistically if you have any aftermarket parts on this vehicle remove all of them and put factory stuff back on because it may not be compatible. Then check ground for bcm and battery to body ground because it may be the problem. The ground is in center of dashif this vehicle was bought new then I'd also contact Toyota on their national number and see if they have an answer to this. If this car h as been in a flood then all bets are off as once a car is in a flood it should be scrapped. Due to problems like you are having and cannot be repaired. Not being able to see this make it very very hard for us to give a correct or even a good diagnosis.
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Wednesday, October 1st, 2014 AT 6:26 AM
Tiny
HMAC300
  • EXPERT
Oother thing you might try is putting dielectric grease at connection of bcm and look closely at connector as something may be bent and not connecting right.
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Wednesday, October 1st, 2014 AT 6:27 AM
Tiny
DANBSHERWOOD
  • MEMBER
Where exactly is the ground at in the middle of the dash? I would think that both the dealer and the other shop have checked this as they had the dash apart, but I can recheck it.
All the aftermarket parts have been on the truck for over a year without issue, so it just seems strange that all of a sudden they would cause issues, but I have not hooked up the tailgate lock since it tied in with the key fob which isn't working. And replacing the tailights is something I'm doing as that was another issue not working and one of the shops thought they might be suspect.
The other parts I hooked back up (piaa driving lights/gauges/7 pin TRD trailer harness to OEM wiring plug) are all still working even though the BCM currently in the truck is currently burned up. So my thought process is that if they are working even with the BCM burned up, they must not be the issue by process of deduction. Is that correct thinking?

Just trying to eliminate each item it could be. The shop saying that it all worked good for 4 hours until they plugged in the HVAC "magnifier". I'm wondering if a.22 casing dropped down through the vent on the dash and got in the ac motor and is causing an issue? Any other ideas?
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Wednesday, October 1st, 2014 AT 8:13 AM
Tiny
DANBSHERWOOD
  • MEMBER
I bought the truck used and have no knowledge of it being in a flood.
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Wednesday, October 1st, 2014 AT 8:15 AM
Tiny
HMAC300
  • EXPERT
Without seeing this makes it very difficult for us anyhow. As far a s ground it would either be on or near bottom of dash on sheet metal area. The amplifier or "magnifier " as they call it grounds at right kick panel so check that ground as well. A 22 casing may make noise or jam blower but you can always pull blower out and see if it can be removed as they can't all the time. Unless the.22 casing was stuck by one of the air motors like mix or direction I can't think it would hurt anything unless it shorted out resistor somehow. I really can' t think of anything else and really engineering should look at this where time can be taken and different areas of the truck can be looked at and tested to resolve this. Ireally don't think we can help on this. Unfortunately
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Wednesday, October 1st, 2014 AT 12:14 PM
Tiny
DANBSHERWOOD
  • MEMBER
Well thx for your help. I will pull the passenger kick panel off and check the ground. That is the area where I tied into a hot lead for the tailgate lock to tie in with the door locks, but it has been disconnected and not hooked back up.

The ac is working without issues as far as I can tell, but I found it interesting that plugging the amplifier for the ac back in was the last thing done when the current BCM was working and before it smoked up so I was just thinking out loud there.

Very DISSAPOINTING that no one seems to have a way to diagnose this problem let alone fix it. Bummer!
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Wednesday, October 1st, 2014 AT 3:43 PM
Tiny
HMAC300
  • EXPERT
Like I said for us to diagnose this is very hard and time needs to be spent to fix it. That is why I suggested calling Toyota on their 800 number andsee if they can help you at all. It really needs for engineering to check it out to see what the problem is. It's one of those quirky things that only time can try to find the problem. Something that a dealer won't spend because he loses tomuch money doing it.
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Wednesday, October 1st, 2014 AT 3:47 PM

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