1969 F100 Instrument Cluster Lights not working, getting half power to the fuse box

[Cmd314]

So take the fuse out and and use a paper clip or wire and make a connection between the fuse terminals? I did that with a wire and it got hot and the headlight switch made weird noises like it was frying like zap noises.

[Ranchero50]

LOL, Welp I'm pretty sure the problem isn't the fuse...

Pull the cluster out and trace your instrument lamp wiring looking for the pinched part that's grounding out and popping the fuse.

[Cmd314]

but would that really prevent power across the fuse if i had wiring grounded out? I feel like the problem has to be at the fuse box, this is so frustrating!

[Ranchero50]

No, you have a pinched wire somewhere in the lamp circuit. The jumper wire getting hot tells all. Those lamps draw a fraction of an amp, getting the wire hot requires a pretty big load. Check around the cluster screws for chaffed wires. Or jump the fuse again and wait for the wiring insulation to melt.

[Cmd314]

what do you mean by a pinched wire? that just refers to an exposed wire? i looked from the cluster to the fuse box at the 19 (blue/redstripe) wire and none of the insulation is burnt or cut.

[Cmd314]

Could it be one of the wires coming from the light switch harness? or does it have to be an issue with that 19 wire?

[Ranchero50]

Take the harness apart. Remove all the bulbs and check resistance to ground on the side of the fuse that doesn't have power with the fuse removed. If you have conductivity, you have problems.

This is basic electrical troubleshooting. Google DC troubleshooting to gain a better understanding of what you are up against.

[Cmd314]

could you recommend an article or video to read or watch?

So im basically testing the ohms for the harness ground?

[Cmd314]

I tested the resistance from the no power side terminal and it read first at 05.0 ohms, then test 2 was 03.0ohms test 3 was 01.9 using the 200 ohms setting on the multimeter. What does this mean.

[Ranchero50]

Did you remove the lamps bulbs? If not you are reading though the bulb elements. With the bulbs and fuse removed you want to read the same as holding the probe in the air. If not, trace your wiring until you get that reading. You are going to find a pinched wire somewhere.

[Cmd314]

I did not remove the bulbs, I will. And I'll test for resistance inside the socket? And I'm looking for 0 ohms?

[Ranchero50]

No, 0 ohms is a dead short (same as you holding the leads together.) You have a short to ground (battery negative) causing the fuse to blow.

[Cmd314]

But my fuses arent blowing, they look just fine. I've installed like 5 with all different amps.

[Ranchero50]

Ohm them...

[Cmd314]

Okay ill remove the fuse and test it.