Hi guys I just spent about 90 minutes looking through anything and everything I could find relating to locks and relays....I wanted to make sure that the answer wasn't already here. I don't see it. So....I have power door locks that will lock but not unlock. My 95 S10 Blazer is a 2-door. So only 2 lock/unlock switches and both switches do the same thing. They lock, but when you try to unlock, there's nothing. Throughout my searching I noticed some discrepancy as to where the lock relay is and I guess it must depend on the year. On mine, it is definitely underneath the first plastic panel on the passenger's side. This plastic panel has the big silver box mounted to it....I'm assuming that's one of the onboard computer modules...the BCM maybe? Anyway the relay is under this panel. And when I lock, it clicks. When I try to unlock, nothing. Here's my question - is there a separate relay that does the "unlock" duties? I only see the one relay there. Would they actually have TWO relays (one for LOCK and one for UNLOCK) and put them in completely different places? One other note worth mentioning, and probably not directly related......when you lock the doors, should it also lock the back hatch too? I'm pretty sure if I lock the doors using the switch I can still walk around back and push the button on the lock and hear the "clank" where it pops the hatch. So I guess that lock isn't working at all. I would tend to think this one relay does the lock and unlock duties and maybe if I change it, it will fix the unlock problem. As for the rear hatch that one may be wiring-related if it isn't working at all. I assume I can walk back there and insert the key and turn it and it'll lock it.
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Well here I go replying to my own thread. Curiosity got to me...I just had to go out and see (yes at 1:15 in the morning) if I was telling the truth about the rear hatch. I stand corrected. If both of the front doors are locked, the rear button will NOT unlatch the hatch...so it's locked too. However I'm not quite sure how they did this.....some sort of "completing the circuit" thing I guess....but if you manually slide one of the front locks from the locked to the unlocked position, the rear hatch button on the back unlocks the hatch. That's without using the lock/unlock button. So apparently they set up some circuit that is completed only when one or the other or both front locks are in the "unlock" position that the latch solenoid back there on the hatch will pop. Then again you guys probably already knew that!
Anyways...off to bed now. I can rest easier knowing that if I lock my vehicle the back hatch is locked too.