Dash Light problems

[Trent_McAllister]

I spent a while going through other threads but I'm not finding anything to help me.

The issue is I have no dash lights other than the high beam indicator light. I had them when I put the truck back together, but when I had the lights on for 5 minutes I smelled electrical smell and next time I started, the lights didn't come on and haven't since.

I did a few things that could of caused it when putting truck back together. It might be the original switch I reused. It might be that I replaced the T5 bulbs in the dash with LEDs and it didn't create enough resistance so it burned up wire?

Truck was apart for 2 years in a dirty shop and painter painted over the fuse block labels.
All fuses check good.
all other lights including tail lights work fine.

Can someone tell me what color(s) wire do I need to check the circuit on the back of dash plug or if it is possible it's just a bad switch?

[Wrenchbender Ret]

The dash lights use a light grey wire. There is a separate fuse for them but you say all the fuses are o-k. LED's would not burn the wires or over load the circuits but would not dim when you turned the handle. You probably have a bad reostat on the light switch.

[rayfinseats]

It might be that I replaced the T5 bulbs in the dash with LEDs and it didn't create enough resistance so it burned up wire? (NOT)

[Mr. 250r]

could it be the circuit thing on the back? that flexible copper thing, not sure if your truck has it i just know my 85 is torn in two places and no longer lights up. Just throwing that out there

[raycow]

Good point. The printed circuit could be damaged. Check first to see if you have power at the dash light fuse.

Ray

[timbuk]

hey this is the exact topic im dealing with pulled out the dash and the printed circuit had damage.Can these be bought repro? Man I hate no dash lights went in to fix the gas guage hate that also!

[panhandler62]

Originally Posted by timbuk

hey this is the exact topic im dealing with pulled out the dash and the printed circuit had damage.Can these be bought repro? Man I hate no dash lights went in to fix the gas guage hate that also!

They are available for at least some years. They can also be fixed if they aren't too degraded.

[planewhisperer]

Some sections of the cluster curcuit panel is wired is series and some in parallel. That means with some bulb elements out some bulb elements will work and some will not. The wiring in the circuit panel is copper protected by plastic so if you had a short or grounded out you will see that area burned.

[TheWhiteElephant]

Replacement printed circuits are available through LMC.

[dmack91]

Mine don't work either, and I noticed that I am missing one of the bulb holders. Will this not allow a complete circuit and make all go out, or are they paralell?

Thanks

[1malo68]

Originally Posted by timbuk

hey this is the exact topic im dealing with pulled out the dash and the printed circuit had damage.Can these be bought repro? Man I hate no dash lights went in to fix the gas guage hate that also!

You canget the printed circuit boards at just about everyplace that makes parts for our trucks.
Classic Industries - $39.99
Year One - $95.00
LMC - $39.95
etc.etc.etc

[Trent_McAllister]

So eight years later, I decided I could no longer stand the problem and decided to diagnose it properly.

Checked the resistance on rheostat on headlight switch - ok
Checked fuse and replaced - ok
pulled dash, inspected all copper, polished everything until all circuits could complete to ground.
checked for power to dash plug with truck on and lights on. - FAIL
after quite a bit more screwing around, I realized there is a short to ground (18 gauge black pin) to (20 gauge gray pin) on the plug in the back of the dash.
the conclusion is there is a burned gray wire shorting to ground somewhere in wiring harness between fuse and plug.
This is kind of DUH as this is what a blown fuse should have told me 8 years ago, but I'm on it now.

So I guess I will search the forums to see if I can pull off the fuse box and wire a jumper from back of fuse box to the gray wire right before the plug.

[VetteVet]

Originally Posted by Trent_McAllister

So eight years later, I decided I could no longer stand the problem and decided to diagnose it properly.

Checked the resistance on rheostat on headlight switch - ok
Checked fuse and replaced - ok
pulled dash, inspected all copper, polished everything until all circuits could complete to ground.
checked for power to dash plug with truck on and lights on. - FAIL
after quite a bit more screwing around, I realized there is a short to ground (18 gauge black pin) to (20 gauge gray pin) on the plug in the back of the dash.
the conclusion is there is a burned gray wire shorting to ground somewhere in wiring harness between fuse and plug.
This is kind of DUH as this is what a blown fuse should have told me 8 years ago, but I'm on it now.



So I guess I will search the forums to see if I can pull off the fuse box and wire a jumper from back of fuse box to the gray wire right before the plug.

I see from your original thread post that you neglected to tell us whether you had the 3 gauge cluster or the seven gauge cluster. It makes a difference where the wires go to on the cluster plug.
Power goes to the no. 3 pin on the seven gauge panel and to pin seven on the 3 gauge panel.
It is a pink wire from the fuse panel and it powers the fuel gauge and the temperature gauge. The lights are powered separately.

to say you have a short between the black and gray wire pins means nothing unless you state the resistance that you measured because you will get a reading between the two points through the light filaments. If you are reading less than 1 ohm then you have a short but if you measure around 10 ohms then you are just reading the dash lights resistance. They are wired in parallel so you should read slightly less than the resistance of one light.

Take a reading on the PNL lts fuse with the cluster plug unplugged and if you get close to zero ohms on either side of the fuse holder then you have a short in the wire from the headlight switch rheostat ( green), or the wire to the cluster plug, (gray).

Don't forget that you have 2 gray wires together on the cluster plug, pin 8 or pin 12 depending on the style of cluster you have. One of these gray wires is the power wire from the fuse panel and the other wire goes to feed the heater panel light, and glove box light if so equipped. This wire is a common source for a short to ground. Before you run a jumper to the cluster plug, do a short to ground check on the fuse panel lights fuse, and if you don't read a short to ground with the cluster plug unplugged then you don't need the jumper . Make sense? Don't forget the heater panel light and that you will read approximately 10 ohms through this light if the bulb is good

Then you can check The cluster for short to ground between pin 7 and 8 or between 6 and 12 if a 3 gauge cluster.

Try these checks and post back.