No parking/instrument lights

[bschmidt]

 

[SnoKing]

Did more troubleshooting today and was able to determine that I'm not getting 12v to the headlight switch. I traced the feed wire down to the big connection plug behind clutch pedal. I used my ohmmeter and it makes a complete circuit from the large connection plug up the headlight switch. I don't have 12v coming in to big plug. So I would say next step is to pull apart PDC? I tried messing around with fuse 19 or fuse F on my box for parking lights and everything seems good with the socket/fuse.

You have 12V on one of the two Fuse F socket terminals?

 

[bschmidt]

Not sure what that connection plug is called. That's where I traced the feed wire from switch to.

 

[bschmidt]

Yes 12v on one side. Put fuse in and 12v on the other side

 

[bschmidt]

I also put 12v jumper wire to pin 14 and insturment lights came on

 

[SnoKing]

Did I see a burnt up terminal?

 

[DavidC]

Ohm from fuse F to C134 pin 35 first

 

[bschmidt]

No, it is black ink on a empty socket

 

[DavidC]

 

[bschmidt]

Thank you for diagram.
No ohm from fuse F to pin 35

 

[bschmidt]

 

[DavidC]

Well you may be right at the PDC. In my time I have also seen wires burnt in half in a wire bundle. Most notable was a fuel pump on a B52, took a week on that one and found it in the middle of the bomb bay tracing from the cockpit to the tail.

 

[bschmidt]

That definitely takes a TON patience.
Thanks for all the help guys. I will keep digging and let you know what I find.

 

[SnoKing]

Sample of where you may have to go next. Not the exact same unit. Or just build a new circuit with fuse around the PDC and wiring.

 

[DavidC]

The good news is it will be a wire from the fuse to C134 which makes sense as most circuit boards are not capable of handling 20 amps. Good luck, I have not had a need to open my PDC although at least one person on here did and I do not remember any circuit boards, all direct wired.

 

[bschmidt]

Good news!!! I opened PDC and no board. Has to be a broken wire. I'm seeing some green corrosion on some wires just after the harness comes out of PDC. Keep you guys posted

 

[bschmidt]

Problem solved!!! Corroded wire was the cause. Looks like it had a test light probe hole in it and good old road salt took care of the rest. The only thing I can think of is I had a guy install an aftermarket alarm and he probably probed that wire with a test light. That was done right after I purchased the truck. Took almost 18 years to fail.
Can't say thanks enough. This club always amazes me with how helpful everyone is.
Thanks for the help!

 

[SnoKing]

Sample of where you may have to go next. Not the exact same unit.

Problem solved!!! Corroded wire was the cause. Looks like it had a test light probe hole in it and good old road salt took care of the rest. The only thing I can think of is I had a guy install an aftermarket alarm and he probably probed that wire with a test light. That was done right after I purchased the truck. Took almost 18 years to fail.
Can't say thanks enough. This club always amazes me with how helpful everyone is.
Thanks for the help!

Perseverance Wins!!!!

 

[DavidC]

Glad it's fixed. Probing is fine but the puncture needs to be sealed, when I was still working I would use 3m scotchkote but it seem's a little pricey for the individual especially when your not using it most of the time. Maybe liquid tape ?. Just a FYI for any future endeavors. It took 20ish years for that B-52 wire to burn in half and it was in the middle of about a 100 conductor bundle.

Had to edit had 50 years, happens when humans age. It was really 20ish.

 

[brucejohnson]

Problem solved!!! Corroded wire was the cause. Looks like it had a test light probe hole in it and good old road salt took care of the rest. The only thing I can think of is I had a guy install an aftermarket alarm and he probably probed that wire with a test light. That was done right after I purchased the truck. Took almost 18 years to fail.
Can't say thanks enough. This club always amazes me with how helpful everyone is.
Thanks for the help!

That's great news. And the fix was relatively simple. I am a probe-o-phobe when it comes to wiring just for that very reason. IF I have to probe I'll use a sewing pin so it leaves a small hole, then dab some RTV on the pokes-n-holes, or seal with tape. But that's ultra rare in my "testing toolbox".