This car's power lock system is so crazy it is not even funny. Got a snowstorm last night, noticed that the power locks weren't working right. Hit the buttons, nothing. Remote= no response. Checked fuses, both PWR LKS and LKS/MIR were good. Pulled the LKS/MIR, heard locks move. Then the key fob works (only driver door, and barely because it stops working after 2 unlock commands and then it locks once after i press unlock!). Then only the lights flash and the relays click when i hit unlock. I think there could be a short because when i put in LKS/MIR fuse, it sounds like it is clicking behind the dash and the locks are engaging as if both lock/unlock circuits are closed at the same time. Then they release when i pull the same fuse. I removed both door lock switches because i thought snow got in them and caused a short. Still have same problem. locks worked perfectly before the snowstorm and i know the only exposed parts of the power lock system are the buttons and they are clearly not the problem. The car is a 1998 GMC Jimmy SLT 4x4 4-door. I am hoping it is not the BCM because i know those run hundreds of dollars. Thanks for any help.



ComputerNerdBD

UPDATE: The locks now seem to work okay when the PWR LKS fuse is in and the LKS/MIR fuse is out, but only with the key fob and for a few button presses within a min. the switches wont operate the locks now, and the rear liftgate glass wont pop at all now. I REALLY HOPE IT IS'NT A MODULE and is something a high school computer nerd who is trying to avoid another repair bill (me ) can fix..........

 

Sounds like you have wires crossed somewhere. It is possible that a switch at one of the front doors is messed up. I would start by disconnecting the master switch and checking for proper operation of the lock switch. Hope it is just a switch for your case as a wiring issue will be FUN to find!

 

I removed both switches on both front doors and the locks are still energized when the LKS/MIR 5A fuse is in and the remote doesnt work. If I only got the PWR LKS fuse in, locks work okay, but only with the remote control and without the rear glass (remote, switch below the 4x4 controls and the button on the liftgate) or the door switches. The connectors going into the switches look in good condition. Seems like this truck is posessed because it is one defect after another. Also got an appointment to get the intake manifold gasket replaced next week.

 

Sounds like the orange wire to the power lock/window switch & power mirror switch in either the driver or passenger door has crossed with another wire. The LKS/MIR fuse feeds into the power lock/window switch as well as to the power mirror switch. If this wire were to get crossed with a lock or unlock wire to the BCM, it could cause the lock/unlock relay to be always active.

 

Some of the GM actuators are wearing out quickly- I just replaced 3 on a 2000 M-Van so meter your lock actuators- if they are getting +12v then -12v for lock and unlock- chances are real good your actuators are worn out especially if they lock once then don't hardly move on consecutive tries Cold weather can make margiinal actuators become inop actuators..

I actually have installed aftermarket actuators and found them to work much better them OEM...

 

The lock actuators themselves work fine, but only with the LKS/MIR fuse removed and only with the remote (no door switches). I also find out that it now works properly (sometimes maybe for a few min) with the fuse in with the door switches, but until I can get someone to check all the wiring to the locks, I pulled the LKS/MIR fuse so I can use the key fob only to lock it up or unlock it so i don't have to contend with the problem (for now since I have much more important things to focus on:school and working on Eagle Scout Rank) or a dead battery since i drive the SUV (SuperGeek Utility Vehicle: the Jimmy ) to school and scout events and can't afford a dead battery (or someone breaking in because the locks could short to the open position) since no one would be willing to jump it because most of the other students at my school drive small sedans and the Jimmy's starter would probably fry the other car's electrical system (so I hear). Maybe it could have been water getting in the door past the window molding at the base of the outside of the window on the front passenger side because I found that lock was hard to move one day by hand, with the key in the door and remote. It moved normally after 30 minutes of driving the car with the heat on max and hasn't acted up since. Must have been water that got in and froze when the temp was 10F. Thanks alot for all the help so far on this problem.

ComputerNerdBD

 

Hopefully it stays that way. If not, post up again in this thread and we will see what else we can come up with.

 

ComputerNerd,
thanks!. Your post was very similiar to my lock problem (snow into open window, locks shut down) and mine now work with a change of the lks/mir fuse which I over looked during many fuse searches.


My take on all the info is.

the mir/lks fuse also fires up the portion of the BCM which controls the rear gate. I was able to power up my door locks with a jumper (much like an alarm would) however the rear gate wouldn't budge at the time the lk/mir fuse was out. Your's is most likely fixed by now, though if not, I suggest unplugging the mirror switch which is a known rainy day quirk for the blazer which might be the culprit short. I suspect yours works for a minute or so and cuts when either thier's heat or too much draw from a short in the mirror switch.
Good Luck!

 

sounds kind of like my problem only my power locks do not work at all and the damn liftgate wont open but im gonna check tha lks/mir fuse

 

well thnx to this thread my problem is solved