02 trailblazer driver door problems


Original poster
Apr 2, 2012
have an 02 trailblazer ltz with 84000 on it, my problems are
1. i get a door ajar warning even when the door is closed
2. when i use the mirror button to adjust the side mirrors, the automatic locks go nuts.
3. my lock button works but unlock does not.

all these problems are on the driver side door. if anyone has any info to point me in a direction for a fix, it would be helpful, thanks all


Lifetime VIP Donor
Nov 19, 2011
Portland, OR
The DDM (Driver Door Module) in these vehicles go bad quite often because water gets into the flat exposed switch crevices and runs down inside and eventually the electronics can be damaged. Swap with a local buddy if you can find one with the same DDM.

The design is that the DDM is a communications center, and sends data messages out to the rest of the vehicle. So if you ever lose control of things totally from the DDM, it may be a bad DDM or a broken data communications wire at the door hinge area where they flex more often than the other doors.

If only one or two functions are flaky, like the mirror control, it may be a problem local to your DDM. The door ajar problem could be in the DDM or in the switch in the latch area that detects door closure, and those can get corroded and need cleaning and lubrication. And the lock/unlock issue could be a simple dirty switch contact area on the PC board or the switch membrane.

Too many symptoms to be all from one cause, unless the DDM is just giving up the ghost. There are so many failures, that Ebay and the junkyards have a low supply, and the prices are going up. New at the GM dealers, they are sometimes on national backorder, and on top of that, you have to pay the dealer to program a virgin one to match your vehicle, a bery unfriendly design decision on GM's part.

I think your best tactic is to try to find a local trailblazer owner and swap with them and see if the behavior changes, then dig deeper into the door latch area depending on what happens with experiment #1.

Do you own a meter and have any electrical troubleshooting experience?


Original poster
Apr 2, 2012
i do have electrical troubleshooting experience, ill try some of the steps you listed and report back, thanks

Forum Statistics

Latest member

Members Online