Power locks not working

[Mr.B]

I have a 98 GMC Sierra pickup and my power locks just stopped working. I have checked all the fuses I could find and they all look good. Please help point me in the right direction.

 

[SCOTTYINWV]

If there is no fuse or relay issue, I would suspect the drivers side switch. I think it feeds power to the other side.

 

[MYT HI]

Yep check both switches

 

[Dr.Zoom]

Do you have a multimeter? Check the fuse for continuity to make sure it's good, sometimes they'll fool you visually. After that, I'd start checking to see if any connectors have come loose. Have you been messing with any wires or anything under the dash? If so, you could have disturbed something. Been driving on rough surfaces or taken any big potholes? If so, you could have shaken loose a connector that wasn't all the way seated. Once you've checked these things, it's time to start checking for 12v at various points along the circuit.

 

[Mr.B]

Where is the relay that controls the power Locks? How do I check to see if they are good? I swapped the switches with my other truck and they worked so I know that the switches are good. I checked for loose connections all checked out good. Thanks for all your help. I do have a multimeter

 

[aaronb]

Also check your abs fuse under the hood.mine popped and my locks wouldn't work.

 

[Dr.Zoom]

Where is the relay that controls the power Locks? How do I check to see if they are good? I swapped the switches with my other truck and they worked so I know that the switches are good. I checked for loose connections all checked out good. Thanks for all your help. I do have a multimeter

About half way down is an illustration to show where your relay is.
http://www.gmt400.com/forum/showthread.php?12481-power-door-lock-issues

To check your fuse, use the continuity function of your multimeter hooking up one lead to each prong of the fuse. It should have 0 resistance(showing continuity). Fuses are so cheap, I'd replace it just for the hell of it.

I'm not sure what type of relay is used, but it should be pretty easy to deduce what's what, there are only a couple wires. You should be able to test that at all times it has 12v on the side that powers the relay and when the lock/unlock switch is activated, 12v should show up on the side that controls the locks. I've never troubleshot the locks, but that's the general relay theory and it should be true here.