Body Control Module location

Good evening,

I posted the procedure for you below.

Why do you think it needs to be replaced?

Roy

BODY CONTROL MODULE REPLACEMENT

REMOVAL PROCEDURE

IMPORTANT:
- The ignition switch should be in the OFF position when connecting or disconnecting the connectors to the body control module (BCM).
- Always disconnect the 40-way body wiring extension FIRST, the 32-way tan connector SECOND and the 24-way gray electrical connector LAST.
- Always connect the 24-way gray electrical connector FIRST, the 32-way tan connector SECOND and the 40-way body wiring extension LAST.
- The BCM can set DTCs with the ignition switch in the OFF position. The BCM has battery run down protection for the courtesy lamp circuit. The BCM battery run down protection cannot detect shorts on inputs or other circuits which the BCM does not control. Use the scan tool in order to activate the POWER DOWN NOW mode. Use the POWER DOWN NOW mode in order to check for current draws on circuits that are not controlled by the BCM, or controlled by the battery run down protection system.
- Do not touch the exposed electrical contacts of the body wiring extension. Do not open the BCM housing. The module does not have any serviceable components. The module may be replaced only as an assembly.

1. Disconnect the negative battery cable.

CAUTION: Refer to Battery Disconnect Caution in Service Precautions.

2. If replacing the BCM on a Chevrolet TrailBlazer EXT or GMC Envoy XL, remove the left second row seat.
3. If replacing the BCM on a Chevrolet TrailBlazer, GMC Envoy or Oldsmobile Bravada, position the left hand second seat to a cargo position.


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4. Remove the rear electrical center cover.


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5. Press down and hold the locking tab (1).
6. Disengage the sliding latch retaining the BCM to the rear electrical center. Slide the latch inboard until fully extended, approximately 40 mm (1.6 in).


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7. Disconnect the 40-way body wiring extension (1) from the BCM.


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8. Disconnect the 32-way tan electrical connector (2) from the BCM.
9. Disconnect the 24-way gray electrical connector (1) from the BCM.


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10. With an upward motion, remove the BCM (1) from the rear electrical center.

INSTALLATION PROCEDURE


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1. Index the slots on the BCM (1) to the rear electrical center.
2. Using a downward motion, install the BCM to the rear electrical center.


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3. Connect the 24-way gray electrical connector (1) to the BCM.
4. Connect the 32-way tan electrical connector (2) to the BCM.


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5. Connect the 40-way body wiring extension (1) to the BCM.


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6. Engage the sliding latch fastening the BCM to the rear electrical center. Slide the latch outboard until the locking tab (1) is fully seated.


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7. Install the rear electrical center cover.
8. If replacing the BCM on a Chevrolet TrailBlazer, GMC Envoy or Oldsmobile Bravada, position the left hand second seat to a passenger position.
9. If replacing the BCM on a Chevrolet TrailBlazer EXT or GMC Envoy XL, install the left second row seat.
10. Connect the negative battery cable.
11. If installing a replacement BCM, program the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration. See: Vehicle > Programming and Relearning

Thanks for the steps I will sure hold on to them. but as for replacing the BCM my dash lights, power windows, locks, A/C, radio and mirrors are not working and I figure it might be the BCM.

They are all controlled by those modules.

Roy

Hey Roy, do you know how to program the BCM for the vehicle listed above?

Yes, but you need to have an advanced scan tool, access to GM web site to download the program to install.

It would be cheaper to have someone do this part of the repair.

Roy

Okay, for example if its not the BCM that is causing these interior accessories not to work could it be the fuses in the rear fuse box that need to be replace?

I doubt it as that would mean there are a lot of bad fuses failing at the same time.

Did you have the body control module checked for codes?

A code reader will not read the system. you need an advanced scan tool to access the system.

Roy

I'm going to have to buy me one of those a advance scan tool. where can I buy one at and what is the best one to use because just the sound of it having one will easily solve problems easily.

Look one line. Snap on, Tech 2 are the best. They go for about $2,000.00 to $3,000.00 for a good one but the tools can be had for far less money on Amazon or eBay.

Roy

I bought a used BCM off eBay for the meantime to get my electrical accessories back again. but still waiting for the brand new one to arrive sometime next week. Will the used BCM need to be re-programmed. do I need to disconnected to battery before installing?

Yes to both. It needs to be programmed to your VIN number.

Roy

Hey ! Roy both my brake lights and turning signal lights work but not my tail lights. could this be cause by the BCM also?

No, the BCM has no control over the lights.

I attached a wire diagram for you to view.

Roy

Hey ! Roy, I fixed the issue. all this time it wasn't the BCM causing my electrical accessories not to work, it was the 125 amp fuse the had gone bad. My mechanic did a diagnostic test and tested it with a fuse tester and replaced it. now all the electric accessories back working again.

Good.

What concerns me is that fuse being bad would have shut off all power to the car and you would have nothing.

There has to be more to the story than the fuse.

Roy

OK, This is a weird one! Brace your self!
My 2005 Chevy Trail Blazer ext sl.
To started the vehicle have to click the drivers door unlock button or the key fob unlock button then turn the key or nothing happens?
Sometimes if the key is in acc. click the driver unlock button the starter will try to start.

I have access to a friends Tech2. Have not asked him but can a Tech2 reprogram a used PCM or ECM on my vehicle?

Yes it can. You need to program the body control module.

Roy

Roy,
Do you think my 2005 trailblazer issues maybe the pcm? having to press the key fob unlock button to start the vehicle or the ecm?

You are welcome to start a new question at the beginning and we can continue.

This question is for the original person posting. Please start a new question and we would be happy to assist.

Roy

Okay, sorry new to the site.

No worries.

Just start a new question and we will be glad to help.

Roy

where is the bcm located and what does it control?

the body control module is under the carpet by the shifter,it controls all electrical in the vehicle like windows and so on here are diagrams below to show you the location and hos to replace it. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.