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Identify electrical block

Thank you. Trying to decipher my Chilton's electrical schematics has left me unsure of what and where everything is. I think I have a short coming off that fuse block. Or a melted wire. Trying to track down why I'm not getting a power to my door locks. Think I'm just going to have to tear into it when I have a couple days off.
 
Okay. Gotcha. Still learning the terminology of all the different components and electrical parts. Trying to find the source of the loss of power to my electric door locks. I know the hot wire going down to the starter had a meltdown sometime back and possibly damaged some other wires in the harness. Thinking that hot lead to the locks is probably in the harness to.
 
Guys jump in here- I can’t remember where the fuseable link is on the truck right now. Make sure if it was at the starter that fuseable link went back in not just wire.
I think fuseable link was at the battery but that’s how my rig is- I can’t remember what year gm trucks had them by the starter….

Side track I know but just because he mentioned it…
 
Will L. said:
Guys jump in here- I can’t remember where the fuseable link is on the truck right now. Make sure if it was at the starter that fuseable link went back in not just wire.
I think fuseable link was at the battery but that’s how my rig is- I can’t remember what year gm trucks had them by the starter….

Side track I know but just because he mentioned it…
Click to expand...
On my 1994 the fusible link going to the load center, or whatever that's called, is up by the battery.

From the factory, on my truck, that was one long, undersized wire, run from the battery, in the same loom as the large starter cable, down to the starter and up to the load center.

I've seen several that were chopped off - eliminating the fusible link - installed on the starter lug with the larger battery cable.

At least I believe that to be altered. I have no knowledge of that every being factory.
 
There should be a fuse in the block under the dash for the door locks. get you a test light connected to a good ground on the cab. then probe both sides of every fuse in the panel with the key on and with the running lights on. look for anything that does not have power on one or both sides. there are diagrams on the web that depict what fuse slot goes to what. most if the time the fuse that powers the door locks also will power something else like the windows. the windows should be on small circuit breakers in the fuse block. if the windows power up and down, then your issue will be a switch or the harness inside the door. usually in the drivers door. the way they are wired, if the drivers door has issues, none of the other doors will work.
 
ak diesel driver said:
Your not understanding, those wires provide power to the fuse block in the cab. If everything else works but the door locks then the problem is in the cab from the fuse block to the power locks.
Have you checked the fuse for the door locks?
Click to expand...
Yes I have checked the fuse and swapped with the known functioning other 30a fuse just to be sure.
dbrannon79 said:
There should be a fuse in the block under the dash for the door locks. get you a test light connected to a good ground on the cab. then probe both sides of every fuse in the panel with the key on and with the running lights on. look for anything that does not have power on one or both sides. there are diagrams on the web that depict what fuse slot goes to what. most if the time the fuse that powers the door locks also will power something else like the windows. the windows should be on small circuit breakers in the fuse block. if the windows power up and down, then your issue will be a switch or the harness inside the door. usually in the drivers door. the way they are wired, if the drivers door has issues, none of the other doors will work.
Click to expand...
I'll look closer into it. I replaced the switch. Can I test the actuator with a battery charger? I'm not hearing anything when I push the switch up or down. Could one bad actuator effect the passenger lock as well? Or vice verca? I ran a simple light tester on the contacts of both switches and not seeing any power at either the switches.
 
Tygrr said:
Yes I have checked the fuse and swapped with the known functioning other 30a fuse just to be sure.

I'll look closer into it. I replaced the switch. Can I test the actuator with a battery charger? I'm not hearing anything when I push the switch up or down. Could one bad actuator effect the passenger lock as well? Or vice verca? I ran a simple light tester on the contacts of both switches and not seeing any power at either the switches.
Click to expand...
There should be power at the input on the switches all of the time
 
With the ignition key in the run position, there should be power to at least one of the terminals of the harness, or switch when the harness is plugged into it.
If possible, get a 12 volt source to the battery terminal of the switch, then activate the switch.
If it then functions be looking at the harness for a broken wire, especially where the wires are constantly bending within the sheath between the door and the body.
 
MrMarty51 said:
With the ignition key in the run position, there should be power to at least one of the terminals of the harness, or switch when the harness is plugged into it.
If possible, get a 12 volt source to the battery terminal of the switch, then activate the switch.
If it then functions be looking at the harness for a broken wire, especially where the wires are constantly bending within the sheath between the door and the body.
Click to expand...
I want to look into it more on my next day off. Thanks for your help I'll update you and let you know what happened.
 
@Tygrr Here is some info you might like.

service manuals here... These are in downloadable PDF form.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...
www.gmt400.com www.gmt400.com

@RI Chevy Silveradoman is there a way to link this info in the above link or files within somewhere in the forum's library of information?

Here is a diagram of the fuse block inside the cab showing the PWR/ACC circuit breaker that powers the door locks.
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And here is the diagram for the door locks. Note. on the link below which is the 1988 electrical diagnostic supplement starting on page 196 of the PDF begins the trouble shooting steps including what pins to test on the switches. I have screenshotted these pages for your reading pleasure below.
www.mediafire.com

1988_ST-375-88-EDM_GM_CK_PICK-UP_TRUCK_ELECTRICAL_DIAGNOSIS_SUPPLEMENT

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.
www.mediafire.com


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