This same problem started with my 98 Blazer three days ago. The locks randomly go crazy.locking and unlocking themselves. It doesn't seem to matter whether the engine is started or not. The electronic locks will not work at all from the inside. The glass hatch doesn't open at all and the rear hatch will not lock. Anyone soling this problem let me know.

 

with my blazer , it all corrected itself within another week of hard driving. i never did find the cause but i can only assume it was some kind of grounding condition with wiring that shook itself loose as i can now exit the vehicle without giving myself a shock which seemed to have happened around same time locks went haywire.

 

Had the same problem on an 89 Suburban a few years back and the problem was the door lock relay.

 

I have a 98 Blazer LT 4dr/4wd with 101k on it. This is my second blazer.
Recently my locks went crazy like you described....up, down, up, down and not consistently. There can be a few things that make this go wrong; first, check your relays (there are 3)...they are under you glove box I believe. If they are cold then they might not be working or electrical shortage to them. If they are really hot then they are prolly working overdrive or there is something causing them to be that way.
I replaced all 3 relays in my blazer (about $160 at my mechanic) and the the locks still went crazy after about an hour of driving. I felt them again and they were really hot like before. So i thought maybe my actuators (actual locks) were getting stuck and causing the relays to go haywire. I popped off my door panels on all 4 doors and the mechanisms that lock the door were full of dirt and dust and grime. I cleaned them out with alcohol and re-greased them....had no problems for the past 2 weeks.

I would recommend checking the fuses first (the pwr doors locks in #7), then feel the relays and pop off the doors panels and clean. if there's still no improvement you may have an electrical short. GL and hope this helps.

 

My fuse chart says the power door lock is number 14 on the inside fuse box.
Is that right and is there another fuse somewhere else?

Alex
2000 blazer 4x4

www.aksnapshots.com

 

Door Lock fuse there is 2 spots above the 15amp fuse in the hood fuse compartment. the pic is not clear but there is a slot between the 15amp and where the 3amp door fuse goes. the one with the red circle is the right spot. mine was in the wrong one..See photo

 

Im not sure I follow you? Whats the fuse in the right spot do? Sould I replace mine to correct the crazy door locks locking all the time randomly? I dont beleive i've caught them unlocking yet? Just locking like someone stuffed an extra key fob under my leather seat skins and as i sit down and move around my power door locks lock randomly. I also have had major issues with power seats not getting power to adjust them either, as the passenger seat heater doesnt work all the time either

 

Is the seat belt latched when it does work? I read somewhere that there is a safety switch so its not on when the seatbelt isn't hooked up.