Power door lock issue

[Raymond Reynolds]

The power locks on the truck will only lock the doors but wont unlock. Ive already replaced both switches with brand new ones from LMC. Anyone else ever have this issue? The trucks a 1987 GMC Jimmy

 

[Colin]

Many times these issues can be traced back to a bad ground.

 

[Charlie]

 

[gmachinz]

The ground circuit for the locks themselves is still the relay-it grounds to the dash brace through the body of the relay itself. Its a pita to get to if your interior is intact.

 

[Goldie Driver]

The power locks on the truck will only lock the doors but wont unlock. Ive already replaced both switches with brand new ones from LMC. Anyone else ever have this issue? The trucks a 1987 GMC Jimmy

I had an issue where the driver's door lock quit operating but the switch still worked the passenger side just fine.

It was a broken wire in the rubber boot between the door and the body.

The switch at the door has 3 wires - hot to lock, hot to unlock , and ground. Since they both work one way it seems logical to look at the wiring from the kick panels to the relay as the odds of a broken wire in the door on both sides seems remote.

Note, however, that I am an electrical amateur and maybe all wrong.

Best of luck!

Britt

 

[Shorty81]

Welcome from the Buckeye State.

 

[C10MixMaster]

The power locks on the truck will only lock the doors but wont unlock. Ive already replaced both switches with brand new ones from LMC. Anyone else ever have this issue? The trucks a 1987 GMC Jimmy

The fact that it locks eliminates most everything but the relay itself.. or two broken unlock wires which is unlikely. grounds are common problems but lock circuit runs through the same ground. try a new relay

 

[Raymond Reynolds]

Hi everybody, and thanks for the help! Any ideas where the relay is hiding?

 

[C10MixMaster]

Hi everybody, and thanks for the help! Any ideas where the relay is hiding?

on my 77 its hiding behind the climate controls on the brake petal bracket 87 they might have found a new hiding place

 

[Raymond Reynolds]

on my 77 its hiding behind the climate controls on the brake petal bracket 87 they might have found a new hiding place

OK cool. I'll start there

 

[KilgoreTrout]

It's up under the brake pedal. Keep looking up. It's a pain in the ass. Click the switch and trace it down.

If it helps any, your power door locks work 50% better than mine.

 

[trukman1]

I had an issue where the driver's door lock quit operating but the switch still worked the passenger side just fine.

It was a broken wire in the rubber boot between the door and the body.

The switch at the door has 3 wires - hot to lock, hot to unlock , and ground. Since they both work one way it seems logical to look at the wiring from the kick panels to the relay as the odds of a broken wire in the door on both sides seems remote.

Note, however, that I am an electrical amateur and maybe all wrong.

Best of luck!

Britt

This is what was wrong with mine which had the same symptoms. The wires inside the boot wear through. PITA but from what I've found researching online it's fairly common in these older vehicles.

 

[Kevro_N_Chevro]

I have been searching to find a replacement lock relay. Anyone have any recommendations


Sent from my iPhone using Tapatalk

 

[gmachinz]

I have several available. Message me if you need one. $35 ea shipped.

 

[Vbb199]

I have the opposite issue. Mine won't lock.

More than likely relay after doing some testing. You may also find it the truck sits for a while the battery is dead. For me , I found the relay is stuck in "lock".

If you find where it's at, show me, maybe mine is nearby. I have a parts truck I can take the relay off of.