Voltmeter no worky, E brake light stays on...

[tex_waco_usmc]

Ahhhh, the joys of swapping an entire harness from one truck to another!

My voltmeter gauge doesnt work at all! Its out of an 87. The gauge worked before removal and reinstallation. This is where not knowing the squares gets me. Is there a wire I am missing? It appears that the back of the cluster has a spot over the back of the voltmeter for another connector (kind of like a weird shaped "D" but I do not remember removing a wire from that spot! What did I do wrong????

Also, when it was all said and done there was no wire to plug into the Ebrake switch. So now the light in the dash stays on. Anyone know where that wire comes from so I can find where it is hidden! LOL

BTW, shes alive and driving again just need to patch up these few last minute things!

[hatzie]

The brake light is run from both the E-brake and the combination valve on the forward frame crossmember. The switch wires provide a ground for the BRAKE light. If they're unplugged the light should be off... so one of them is shorting to ground.

The voltmeter is run from the main instrument cluster plug. There is no separate wire for the voltmeter. I assume the other three gauges work. Pull the volt gauge out without removing the cluster bucket and test that you have volts at the spring clips with the ignition on. You can go from there.

The GM 73-86 CK & 87-91 RV series wiring diagrams are in my signature. The 1987 & 1988 wiring manuals have a really strange layout. 1989 is easier to follow and should be pretty close. 1990 & 1991 RV series wiring manuals have harness routing and plug location information that should apply to the 1987 RV but have more computer controls than the 87-89 RV models. I'd download the four 87, 89-91 wiring manuals to your PC and go from there.

[motornut]

I'd test as mentioned
my 78 dosn't have that "Ebrake"switch
both 79s do

[tex_waco_usmc]

Originally Posted by hatzie

The brake light is run from both the E-brake and the combination valve on the forward frame crossmember. The switch wires provide a ground for the BRAKE light. If they're unplugged the light should be off... so one of them is shorting to ground.

The voltmeter is run from the main instrument cluster plug. There is no separate wire for the voltmeter. I assume the other three gauges work. Pull the volt gauge out without removing the cluster bucket and test that you have volts at the spring clips with the ignition on. You can go from there.

The GM 73-86 CK & 87-91 RV series wiring diagrams are in my signature. The 1987 & 1988 wiring manuals have a really strange layout. 1989 is easier to follow and should be pretty close. 1990 & 1991 RV series wiring manuals have harness routing and plug location information that should apply to the 1987 RV but have more computer controls than the 87-89 RV models. I'd download the four 87, 89-91 wiring manuals to your PC and go from there.

Im going to do just that for the voltmeter. I am going to say that I have a bad voltmeter but I do have about 5 extra gauge clusters so I should be able to make one work, but before I pull parts I am going to test to see if it is getting juice.

If I had to guess I am going to say that I plugged the Ebrake switch wire into the 6 prong ground point that is bolted to the firewall behind the gauge cluster and thats why the light is lit. LOL, I was in a hurry and when I was done I couldnt find the ebrake wire anywhere!

[tex_waco_usmc]

Someone correct me if I am wrong, but the Ebrake switch wire is Tan/Wht? I am pretty sure I read the schematic right, but wanted to verify!

[motornut]

my 4X2 79 appears to be the tan/white

[tex_waco_usmc]

Ok, so plugged the appropriate wires into the ebrake switch and still have the brake light in the dash. Pulled the wire off of the combo valve for now because the light was making me look like this: ... Still working that issue.

The voltmeter I havent had a chance to check yet, but planning on doing that after I give the engine a little tune-up. Hoping to correct some backfiring through the exhaust that I am currently experiencing at idle/ low rpm... Once I get to about 1500 RPM the pop goes away...