The diagram posted above does not apply to your truck.
1998 chevy silverado door lock fuse.
Door lock relay in left fuse box.
The picture of where the power door lock relay is located is on page 261 of my 92 schematics 92 gm factory electrical diagram manual.
Niether door lock button will operate the locks but the key fobe remote will.
Pull off the cover to access the fuse block.
Sorry but i m not an installer just an owner trying to find a solution.
Gmc sierra mk1 1999 1998 fuse box diagram.
Pull off the cover to cover to access the fuse block.
When i press any unlock button there is a clicking near in the interior fuse box.
15a unlock fuse located in left fuse box.
You may have spare fuses located behind the fuse block access door.
If they do not then you may have a bigger issue.
The power locks will lock just fine.
The door lock relay is located under the center of the dash.
All unlock fuses have no power when i check them with the test light.
The only way to get into the truck is using the actual key.
There is no power going to any of the locks when i try to unlock them.
If you have a different schematics and it is not on that page look in the table of contents in the front for power door locks then turn to that section in my book starts at page 199 then under the component location heading it should list on what.
You can remove fuses with a fuse extractor which is mounted to the fuse block access door.
For 1996 chevrolet 1500 the fuse block door access is on the drivers side edge of the instrument panel.
I read right past the c3500 part of your post.
1998 silverado door lock.
Put a test light on the 15 amp lock fuse and press the.
So your truck is an obs gmt400 and you should be looking for info up to 1998 not 2000.
To remove fuses if you don t have a fuse extractor hold the end of the fuse between your thumb and index finger and pull straight out.
Could the driver side control pod be the problem.
The fuse block access door is on the driver s side edge of the instrument panel.
Driver door unlock relay in left fuse box.
1998 silverado crew cab puthe problem.
Door lock relay in left fuse box.
If they work then you ve narrowed down your problem.
One of the easiest ways to diagnose the switch is by trying to use other door locks in the car.
Since the door will unlock but won t lock it would seem to be a problem with the gray blk wire at the lock actuator.
Gmc sierra mk1 fuse box instrument panel.
Instrument panel fuse block.