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bcm replacement problems

15K views 26 replies 7 participants last post by  Ryengoth 
#1 ·
hi all i have a 2005 colorado with a bad bcm tried everywhere to find a new one gm says its discontinued tried reman everyone seems to use dorman but dorman says no availability and not expecting that to change so that leads me to used great i found one installed everything works except it actually starting and running due to bcm vin does not match truck so passlock has fuel system shut down which i expected as everyone says it would need reflash so no problem i called gm and wrong its a big problem as gm says that they cannot change the vin on a colorado bcm and they have no way to fix the problem. has anyone been able to find a way to fix this?
 
#2 · (Edited)
Have you attempted the Passlock security relearn process? The one that takes about 30 minutes? I am not sure that will work anyway until the BCM is programmed, but its free.

And the dealer is telling you it cannot reflash the BCM to your VIN? Have you called another dealer? Are they saying you are stuck until you can get a reman BCM?


that thread looks promising for a repair tech.

or this?

 
#3 ·
I tried the security I found but I may not be right it was key on crank back to run for 10mins on turn key off 30sec turn key on try to crank still no start. Is this the correct procedure? If there is another i will give it a try.

As for the dealer my local dealer says once a vin has been programed into the bcm it can not be changed and said they have one in their shop now they have had for weeks due to not being able to reflash called another gm dealer he said he could try if I brought the truck and left it but that they have never been successful with anything but new bcm. I am a mechanic for the local municipality where I live and know the service man at the local gm personally and he says that pretty much unless I can find a remaned bcm with no vin stored the truck is unrepairable and basically worth scrap as gm will not give them the ability to change a vin once its in a module.

My next question to him was if a gm dealer cannot remove a vin how does a reman company ie Dorman remove the vin so it could be reflashed? And is the any way to actually bypass the passlock all together?
 
#4 ·
Those are very valid questions on reman. Maybe give that Ebay vendor an email to see how they work....

You can bypass Passlock in a couple ways. Have a PCM tuner execute a VATS delete on that module. Or, cut the signal wire to the BCM with the truck RUNNING. Thats the tricky part right now. Do some searches on security bypass here. There is a lot.

I do not know how that will work in your situation right now though.

Your procedure is correct

Turn key to crank, then let it sit at run for 10 minutes (until security light turns off)
Key to off for 30 seconds
repeat 3 times.
On the 4th try it should start.

Again, that is in question due to the non native BCM....
 
#6 ·
From the 2005 shop manual:

BODY CONTROL MODULE PROGRAMMING AND SETUP

BODY CONTROL MODULE (BCM) REPLACEMENT

If the body control module (BCM) is replaced, the following procedures must be performed in the following order:
  1. BCM Reprogramming-Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
  2. Learning the restraints ID-Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
  3. Theft Learn-Refer to Programming Theft Deterrent System Components in Theft Deterrent. A new BCM will learn the Passlock information automatically but the PCM must still learn the theft information from the BCM.
  4. Program Key Fobs-Refer to Transmitter Programming in Keyless Entry.
BCM REPROGRAMMING
If the body control module (BCM) is reprogrammed, the following procedures must be performed

  1. BCM Reprogramming-Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
  2. Learning the restraints ID-Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.
  3. Theft Learn-Refer to Programming Theft Deterrent System Components in Theft Deterrent.
  4. Program Key Fobs-Refer to Transmitter Programming in Keyless Entry.
INFLATABLE RESTRAINT SENSING AND DIAGNOSTIC MODULE (SDM) REPLACEMENT
If the sensing and diagnostic module (SDM) is replaced, learning the restraints ID procedure needs to be performed. Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.

PASSLOCK SENSOR REPLACEMENT
If the Passlock Sensor is replaced perform the theft learn procedure. Refer to Programming Theft Deterrent System Components in Theft Deterrent.

KEY FOBS REPLACEMENT
Refer to Transmitter Programming in Keyless Entry for the proper procedure.
 
#7 ·
...and WRT the reference for the "Programming/RPO Configuration..."

BODY CONTROL MODULE (BCM) PROGRAMMING/RPO CONFIGURATION

INTRODUCTION

The procedures below are designed to set-up the body control module (BCM) correctly during BCM related service. Before you start, read these procedures carefully and completely.

IMPORTANT : The following procedures must be followed:


  1. Programming the BCM
  2. Learning the restraints ID
  3. Programming Theft Deterrent System Components
  4. Program Key Fobs
PROGRAMMING THE BCM

IMPORTANT
: After the procedure is completed, the personalization settings of the BCM are set to a default setting. Inform the customer that the personalization must be set again.

Perform BCM special function "Request BCM Info. for SPS", then follow the instructions on the screen. Refer to Service Programming System (SPS) in Programming and Setup for more information.

LEARNING THE RESTRAINTS ID
Perform BCM special function "Setup SDM Serial Number in BCM", then follow the instructions on the screen.

PROGRAMMING THEFT DETERRENT SYSTEM COMPONENTS
Perform BCM special function "Request VTD Info. for SPS", then follow the instructions on the screen. Refer to Programming Theft Deterrent System Components in Theft Deterrent.

PROGRAM KEY FOBS
Refer to Transmitter Programming in Keyless Entry for the proper procedure.

IMPORTANT : After programming, perform the following to avoid future misdiagnosis:


  1. Turn the ignition OFF for 10 seconds .
  2. Connect the scan tool to the data link connector.
  3. Turn the ignition ON, with the engine OFF.
  4. Use the scan tool in order to retrieve history DTCs from all modules.
  5. Clear all history DTCs.
 
#8 ·
My 04 w/100k shot craps on the bcm; replaced entire edition new key and salvage bcm mileage now shows 189k and same no start.

Sending my original bcm to G7 computers in Canandaigua NY for them to repair. This the only place I located that may fix the problem. I asked them to delete passlock and to test the entire board.
 
#11 ·
Keep us posted. Glad the truck is at least functional now. Big step there.
Im curious about that BCM clone service from the Ebay link. That might be the ticket.
I don't think a VATS delete in the PCM will free your radio . You will need expert advice on that though. Perhaps it can be deleted from either side of the handshake .
Knowing that a used BCM will allow the truck to run is a big deal. Now to tidy up the rest.

So they can delete pass lock from the BCM side too? OP will be interested in that too.
The cluster will display the greater of the mileage readings, so that is why yours shows 189k now.
Did you do the 30 minute relearn process, and still no start?
 
#10 ·
Latest update I was able to get the truck running with the 30min key on key off relearn but security light now stays on all the time radio is locked and ecm and time both have codes for bcm pass code incorrect but truck runs and drives now to find a decent priced tuner to have them disable vats
 
#16 ·
Yo. Im having the same exact issue. 05 canyon. Bad bcm.
What do you suggest from what youve learned?
I just picked up a bcm from the junk yard. But im nervous to use it.
I would send your BCM to G7 computers in NY (Google them). They fixed my original BCM. I am waiting for chevy to build new software cause the GM software they have will not work on my truck presently. It's a GM thing ya know.
 
#19 ·
That G7 is a solid option, if its repairable. Also look at this on Ebay:
I have not used that service, nor am I promoting it. But it looks like it has potential for those that are trying to use a junk yard BCM.

In their FAQ they mention that the used BCM may cause mileage readout issues if it is higher than your cluster. Worth an email to them for more info.
 
#20 ·
Ooo yea ill check out what they have to say.
Here is my blan B and plan C
I have a GM specialist near where i live imma call them and see what they say and if they can do anything for me. If not car quest says they can send it out to be reman. If not mine reman. Then maybe this new one i got.
 
#26 ·
So, new twist to the BCM replacement issues. I purchased a donor BCM off eBay. I used my Tech2 to configure the BCM serial and it worked. The cluster updated with the wrong mileage (as expected) and I was able to program my keyfobs. I also relearned the crank sensor (which was ODD that it forgot the profile). The unlock process did NOT work. Can't crank t he truck, I put the original BCM back in and took it to my dealer, explained the situation, and they tried with their MDI setup to set the VIN in the BCM. It would get about half way and hang-up. Not good. Is this donor BCM faulty or has anyone seen the "fading of keyfob range" and TPMS failure due to a wiring issue that burns up BCMs? I've already spent almost $250 on the GM software card and the "good" donor BCM at this point. The dealer wants to do a full diagnostic and harness trace now.
 
#27 ·
I was able to reset a donor cluster to get my truck back to OE setup. It immediately picked up the correct mileage from the original, flakey BCM. The BCM started working again, randomly, allowed me to reprogram the fobs with the tech2 and then poof back to no fobs and TPMS. I did have an aftermarket stereo kit installed for a short time with the onstar adapter. It never worked right, I swapped the oe radio back in and I am wondering if it caused an issue with the BCM and/or another module.

The cluster and BCM have to be updated by changing the eeprom data, off-board. You can modify the mileage and VIN from the BCM eeprom, but you risk upsetting the odometer police. 👮‍♂️ I 'fixed' a spare cluster for the dealer to use if they somehow screw up my mileage by setting up a new BCM wrong. Once they roll forward, they do not roll back. Well not without data hacking. LOL
 
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