Hello, new to the site and I have been reviewing the posts on the subject of power door lock issues and can't seem to find my issue listed. I may have missed it, if so, I apologize. I have a 2004 4 door Blazer with 4 wheel drive, and the other day my power locks stopped working at the doors and the key fobs. Now, I have an aftermarket auto start and the fob activities the door locks also. Neither front door activities the door locks, either does the key fob now. When the truck is running and you either put the the vehicle in reverse/drive or to park, the locks would activate in the past, now nothing. I also do not hear any relay click. I have checked the 3 truck fuses (2 inside and one under the hood) and they look good and check out fine when metered. I also checked the fuses that are for the auto start system and they are also good. The rear hatch works and auto start also works. So I assuming that no power is getting to the relay(s)? What do I need to check next? Thanks, Brian

 

sounds like an output line is broken or dead pin on a module that controls them, im not familiar with '04 trucks but iirc but the Keyless entry module is its own separate piece on '99-'01 and so unless its not receiving power from some sort of common im not sure, and the doors locking when in gear is new too. tried replacing the relays yet?

 

Hello, No, I have not replaced any of the relays yet. I wanted to see what feedback I could receive from the forum first.

 

Relays should be very cheap, and they are mechanical devices so they will fail at some point.

Check for power at the relay first, as in pull it out, check its activation and hot side input pins, do you have 12V? should you have 12V at that location, etc, etc.

 

Thanks for the information. I will try this next. Brian.