Cluster Issues

[BHicks79]

85 C10

First, just let me say thanks for every one's help so far! After all the wiring nightmares, i reinstalled the cluster and dash just to find that my dash lights are not working, and whats worse, when i turn my lights on my fuel gauge moves to empty. Am i looking at another ground issue or is it something else? Any help is appreciated...

[bd]

There is a persistent poor ground issue.  Did you ever do this...

Did you do this...

Verify that the ground strap connected between the firewall and the back of the right cylinder head is intact and that the connections are shiny clean and tight.

How did you go about correcting the wiper switch ground?  Be explicit.  Where does the ground connect to the cab?

[zieg85]

85 C10

when I turn my lights on my fuel gauge moves to empty.

This was my problem exactly when I found this forum so many years ago.  Even though I couldn't see the problem the printed circuit on the back of my cluster had a bad spot in it.  I changed the whole cluster with a Pick and Pull find and the problem went away.  I then swapped all my original gauges back in the new cluster and problem solved.  Neat thing is the replacement I found came with a clock and I took the wiring plug and ground wire.  My $.02

[BHicks79]

BD, I did exactly what you told me to do with the strap and nothing changed. After speaking with a mechanic he told me to trace the ground wire coming off the wiper switch harness and make sure it was intact. After doing this I found there was not a ground connected. I ran a food ground to the wiper switch harness and that fixed that issue.

The new ground is connected to the ground buss under the dash next to the e brake.

[bd]

Do you have a voltmeter?

Zieg85 may well be on the right track regarding connections between the PCB and cab sheet metal, but I want to make sure there is no external cause before pursuing that.

[BHicks79]

Yes i do...

[bd]

You may need to extend the meter leads to perform the following.  Set the voltmeter to 20 DCV or lower.  Clip the negative voltmeter lead directly to the battery negative terminal.  Switch on the ignition and the w/wipers then probe a shiny bare metal spot on the cab.  Is there a voltage indication greater than zero?  How much?  If the measurement was zero, continue with the following steps.  Otherwise, stop and report.

Switch off the ignition and wipers.  Tip the cluster out of the dash so you can access the PCB while the cluster is connected to the I/P harness.  Place a towel to protect the cluster lens from scratches.  Clip the negative lead of the voltmeter to a shiny bare spot of sheet metal inside the cab under the dash.  Switch on the instrument lamps and rotate the headlamp switch knob all the way CCW.  Now, probe both sides of every dash lamp socket.  Each instrument cluster bulb that is powered by the headlamp switch should measure battery voltage on one terminal of its socket and zero on the opposite terminal of the socket.  Do any of the bulbs register >0 voltage on both terminals?  Use a felt marker to ID them - record and then post the voltage measurements.