Electrical Help-no running lights

[Unoman]

Here is what I got

My running lights are not working. No tail lights, rear side marking lights or front orange lights. Instrument cluster lights are not working either. When I pull the switch out half way to parking/running lights, nothing happens. When I pull it out all the way, the headlights come on and amp meter indicates a draw, bus still no tail lights, running lights etc.

Headlights are working
Brake lights are working
Both blinkers are working

I removed the switch yesterday to clean up all connections which also allowed me to clean up some hack job PO work. Put it all back together and I still have the same issues.

Any ideas? I am not sure where to check the grounds that might be causing this issue....learn me!!

 

[77mustard40]

Craig I think you are describing two different circuits, headlights and running lights but we'd have to check a wiring diagram for your year. That's actually not a bad start so you know the fuse # etc.

First is to pull the fuse and clean the fuse block ends with fine Emory cloth to make sure you have power across the fuse. Next go to a running light like the ones on the side and test the incoming wire for power with a multimeter buy grounding to the frame under the truck with the neutral lead. If you have 12v coming to the light then it's a ground problem. Good luck.

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[davegonz]

I bet you it's a ground issue.

Here's Coolerman's schematic repository. Coolerman's Electrical Schematics and FSM File Retrieval

 

[Lake Rat]

Yeah, possibly a ground came lose during the new engine install.... somewhere....

 

[Unoman]

Headlights are seperate. It appears that all non-working lights in my situation are runnning on the same circuit. Very 1st 15amp fuse on top in the fuse block. I only visually checked the fuses. I'm going to remove, clean and replace them when I get home. Fingers crossed this is it

 

[77mustard40]

Yea I have had two such issues in the past. One was the headlights, sporadically when I pulled the switch I would have no headlights but everything else. Turned out to be the box, some serous contact cleaning and a new fuse and presto.

Second time was your current problem but after rear sill and tub bodywork, this one turned out to be a ground. Ended up running separate grounds from the markers on the side to the frame in the rear, I think these started getting actual ground wires as opposed to grounding through the mounting bolts around 79. Made sure I really cleaned the bare metal for the ground wires and I was back in business.

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[Unoman]

My rear side markers are ground to the mounting bolts. I wouldn't think that one bad ground on one light would cause them all to not function. Seems like it would be isolated to the one light with the bad ground. Supose anything is possible with these trucks.

 

[FJsnoozer]

A couple of poor grounds caused all of my lights to not work. I was amazed when all of my lights worked after I went through each dead bulb and ground and cleaned it. Again, I lwent from no lights to all of my lights in working order in an afternoon.

Its really amazing how finicky they are. It helps to have an electrical engineer helping.

 

[Unoman]

Problem fixed. Bad connections on the fuse box. Sure glad was an easy one. See yall Saturday morning