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Pete, GMC Technician
Category: GM
Satisfied Customers: 24203
Experience:  14 years GM dealership technician and training.
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2002 GMC Yukon Denali: the alternator..fuse box..Interior Lights

Resolved Question:

2002 GMC Yukon Denali: I just had the alternator replaced and after picking it up from the repair shop the interior dome lights don't work and the Security indicator in the message center stays on. I have checked all, 3 total, of the fuses that indicate, either in the owners manual or on the fuse box cover, they were for Illum, Interior Lights and they seem fine.
Submitted: 5 years ago.
Category: GM
Expert:  Pete replied 5 years ago.
Hello,I will be glad to try and assist you with this,Welcome to Just Answer.


The vehicles body control module if it has an internal fault can cause these problems here in your vehicle.

Usually with the security light being on this would indicate a theft or security problem and then the vehicle would not start in most cases.

But with both of these failing like this at the same time then I think you may have an internal fault in the body control module.

What could have happened is when the alternator was replaced some of the wiring may have shorted and caused a fault in the body control module or may have damaged the body control module.

I would have the fault codes checked in the computer systems to see if a fault is set in the body control module and if it can be repaired or if it has to be replaced.

If it has to be replaced then a dealer would have to setup and program the new module to operate properly in your vehicle.This could have been an accidental mistake made by the repair shop that replaced the alternator and I would bring this issue up with them to see if they will cover or help cover the costs of the diagnosis and repair.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Customer: replied 5 years ago.
When i took it back to the repair shop earlier today they said that because the body control module controls many more things that the two items referenced it could not be the module because the other things controlled by it also would not be working. Is there another fuse or two that I could, should check?
Expert:  Pete replied 5 years ago.
This is true the body control module does control allot of other components but these are all individually fed components from the body control module on different circuits so the body control module can fail on these circuits but the rest may work properly.I would still have this tested to see if it is or isn't sending the right signals out for the lights.If it isn't then the BCM is at fault and would need replaced.

The only fuse that powers these is the CTSY fuse in the under hood fuse box,this is fed power directly from the battery with no other fuses in the path,if you have a test light you can test to make sure this fuse has power on it at all times key on or off by probing the top of the fuse at the metal terminals.If it has power at all times then the BCM isn't sending the ground signal to operate these lights which leaves the BCM most likely at fault.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
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