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Hey guys, I,’ve got an 03 trailblazer that the master switch for my windows and locks just went out about two to three weeks ago. I got a new one from ebay, plugged it all in and now still nothing. Yes i’ve tripple check all of the fuses, and before that I went ahead and verified that I had power and or ground at all the harnesses. everything seemed to check out. I am a rvia registered technition, however not an auto tech. most of my projects are weekend/ shade tree jobs, but this one is about to tick me off. Never had a prob like this with my 90 s10 blazer, my 98 ram, or my girl friends explorer. I did just recently heard that it may have to be programed to the truck. That’s above my pay grade if you know what I mean. never heard of that before or if it even hold water. Have any of you run into this before? right now she dead in the water, I won’t even atempt to drive her until I can resolve this issue. Any thoughts would be greatly helpful. Thanks in advance, and as always stay dirty.
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Attached is the wiring diagram for that system. There is also the body control module (BCM). The BCM has to be flash programmed for the vehicle,
the DDM does notCorrection: beginning in 2002 they DO have to be programmed. The dealership service department has to do the programming. No way around that. The diagram shows two dotted line boxes, one I marked “switch” the other “DDM” … the one marked switch is for the rear and the one marked DDM is for the front. They are separate modules from the BCM.Well how do you like that? The Chevs used to be my favorite hands down. In your opinion, is that going to invole any thing with the fob ? From what i understand, That signal goes to the controller at the lift gate? That has not ever worked since we bought it used. BTW thank already.
The fob communicates with the RKE receiver which is built into the liftgate module (LGM). The RKE receiver communicates with the BCM via the DLC network. The BCM then commands the locks on the DDM, FPDM, and LGM through the DLC network. A problem with any of those modules would prevent the locks from working. See diagram below. Since there is now an issue with the windows, it may be the BCM at the root of both issues. Then again, the liftgate module may just have a broken wire in the liftgate harness–they are prone to a lot of flex. My recommendation would be to put the original DDM back in the vehicle and have the BCM scanned at the dealership or anyone with a GM Tech 2 or Tech 3 scanner to confirm a diagnosis. NOTE: GM will not re-flash a used BCM, only a “blank” one, and it costs around $90 for the programming. If you have to replace the BCM, it must be purchased new. There are aftermarket parts sources that will sell a new BCM cheaper than GM. RockAuto has one for around $70 (although with a $200 refundable core charge :blink: )
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