2006 4 door TrailBlazer Woes
Random loss of all power locks to all doors and rear hatch i.e all doors and hatch locks will not respond to the remote fob or to any of the switches on the doors. When this happens, all of the power windows will not work either.
Also, at times, when i put the vehicle in gear, I will hear the rear hatch mechanism apparently trying to lock..click, click, click etc. That is a sign that all of the switches and remote is in the DEAD stage.

Then I may drive to my destination and manually lock the doors, come back out after shopping and the remote may work and all the power abilities are back and happy.

It is driving me Nuts as once I load up the back with groceries and drive home, if i cannot unlock the back hatch with the remote, I have to crawl over the food stuff to access the emergency hatch latch.

Because it comes and goes, I am making an assumption it may very well be a dirty contact somewhere but I am at a loss to where to start looking. I have done the usual ... replace the battery in the remote. which was a useless waste of time but that was before I realized that the door and window switches were all Dead too.

I've pulled the cover off the relay/fuse box in the back seat area and reseated the relays.

I looked through the posts but would like to ask help from you good folks to guide me in the right direction to solve this.

Thank You Kindly

 

From the sounds of it, there likely is a circuit breaker on that circuit that is being overloaded and tripped, resulting in an open circuit. The rear hatch trying to lock continuously might be the catalyst for the overload. I do not have access to the wiring diagrams for this model so I can't say for sure if this is the case. Hopefully someone can provide the relevant wiring diagrams.

 

Are the circuit breakers you mention self resettable or , like home circuit breakers, something that has to be reset manually?
Also can I assume that there is a code on the computer that tells just what is going on?

 

If it has a circuit breaker, it would be a simple bi-metal self resettable type circuit breaker that will reset once it cools down.

*EDIT* - After doing a bit of reading, it looks like my assumption that there is a circuit breaker in there is incorrect. It looks like there is a lot of communication between quite a few components that is required to lock/unlock the doors. There is a module in the front driver door, the front passenger door, and the liftgate. The rear doors are controlled through relays by the BCM (body control module). The door modules, liftgate module, and BCM communicate with each other. It is possible that there is a problem with one or more of these modules inhibiting communication sometimes. It is somewhat common for the driver door module (what houses the window & lock buttons - possibly the heated seat buttons, if equipped) to go bad if it repeatedly gets wet. In fact, I believe that there was a recall on some GMT360 platform trucks for a possible fire hazard in the DDM -- Yup NHTSA Campaign 13V248000 was for that exact failure.

Given that there has to be communication between modules to accomplish the lock/unlock processes, there most definitely should be codes present if there is a communication issue present. They would be Uxxxx codes and would require a scantool capable of reading the BCM to pull the codes and diagnose the condition.

 

Thank you kindly. I had the recall done when it was first announced. I seem to remember that it was due to a fire hazard and the problem came up afterwards but too much after to get it repaired under the recall.

I'll now pull the switch modules out and see if they are looking knarly and do a little cleanup on them.