Replacing the BCM on a Chevy impala 2003

Ok so after driving for 4 hours, my chevy impala 2003 started to make clicking noises. The clicking was coming from the left side of the dashboard, from the driver side. What had happen was a faulty relay, causing issues. Another thing that was making it worst, was a faulty, from manufacturer BCM (body control module).

So the clicking got worst, until it stopped. Right after it stopped, the battery light and the “service vehicle soon” light came on.

After this incident, a fuse was busted. Replaced the fused, same thing happen. But before the fuse went out, the bcm started smoking.

note: Get the new one. I got a rebuild BCM and when I took the car to the dealer to reprogram, the rebuild BCM was already programmed with another vin number

So I got started on taring down my car:
So lets get the old BCM out!

Started by removing the cover, under the steering well.


Then removed the aluminum cover.


The BCM is located all the way under the steering wheel shaft.

The connectors are colored, pink, white and blue.

This is what the BCM looks like:


After taking out the old BCM, I went and got the new one. So, I went to my local auto part store, they had 2 options. The new $200.00 and the “rebuild” $85.00. Obviously I got the cheaper “rebuild” option.

I installed it, connected the cables to it and put everything back together.
I then went ahead and turned on the switch, locked!
It looked like it was working fine, but the stereo was locked. I then tried to start the car, no luck!

After this i started to search online and found a website that listed a method, for unlocking the new bcm. This method will transfer the lock codes from the car, to the new bcm. With this, i finaly got my car started.

OK, try the relearn again.
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, then release the key to ON (vehicle will not start).
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
Turn OFF the ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes (the vehicle is now ready to relearn the PasslockTM Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK).
Important: The vehicle learns the PasslockTM Sensor Data Code and/or password XXXXX the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
Start the engine (the vehicle has now learned the PasslockTM Sensor Data Code and/or password).

Although i got the car started, the stereo was still locked! I was not able to hear music, and a “service vehicle soon” and “check engine” lights where on. With the car running, i took it to GMC, for them to unlock it and get it fully functional again.

After an hour, the tech told me that

the Rebuild BMC is already programed with another vin number

what did that ment? That i had to start all over again. The car ended up running and working, but with the service lights on.

The next week, i went to get a replacement for the bad BCM. They ordered another one, and after 3 day i had on my hands. So i went to GMC and schedule another appointment. Since they were not able to fix my problem the last time, this next appointment was going to be free, yes!!!

I took the car in. Because i didn’t want to reinstall the BCM and make it learn the codes again, i took the car in and explained to the tech that i still had to remove the bad BCM and physically install the new one. I took the car in and removed the old bcm and installed the new one, “piece of cake!!!”.

After another hour, Finally my car was fully functional again! No service lights, no errors.

Things that i learned:

  • On computer related parts don’t buy rebuild!
  • make sure to keep all receipts specially from auto parts!

2 thoughts on “Replacing the BCM on a Chevy impala 2003

  1. john

    i have a 02 impala when a bcm stops working will it still work intermmeadiatly. i take battery cable off and put it back on radio will work and battery light service soon light and security light go off for a 1/2 houre or so is the bcm bad or not thanks john

    1. elamigosam Post author

      I am not a mechanic, but I would consider that as a sign that its going bad. Maybe you wanna get ready to buy the bmc.


Leave a Reply

Your email address will not be published. Required fields are marked *

Connect with Facebook

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>