Ground connection on instrument cluster

[greenacres]

I have been working on my 1979 Chevy K10. I have progressed to the point that I am ready to install the instrument cluster and dash. The ground wire that goes to the instrument cluster was missing when I got this truck back from the body shop, but I can easily make a new ground wire.

I have looked and looked and I can’t find anyplace on the instrument cluster to connect a ground wire. Can someone please tell me where the ground connection is on the back of the instrument cluster?

I don’t know if this makes any difference or not, but the body shop replaced the cab and I think it is from a 1977 C10. I don’t know which cab the instrument cluster is from, and I am not on speaking terms with that body shop.

[bd]

1977 GM Wiring Manual

1979 GM Wiring Manual

The instrument cluster ground has three wire connections to the instrument cluster PC board.  The ground pinout locations through the 1977 and 1979 18-cavity instrument cluster connectors are different.  Nevertheless, in all cases, ground wires are black and identified as circuit 150 on factory wiring diagrams (refer to the wiring manuals linked above).  The three black instrument cluster ground wires are spliced together with other black ground wires inside the factory cab harness.  A single black ground wire connects that splice to the park brake pedal frame or cab sheet metal.

When you look at the 18-cavity instrument cluster connector, the three black wires are the ground connections to the cluster.

[greenacres]

To clarify: I am talking about the ground wire that connects to the park brake pedal frame.

It appears you are saying the ground wire connects to the wiring harness, but I don’t see anyplace on my new wiring harness for it to connect to.

[bd]

If you have a new wiring harness, the ground wire that connects to the brake pedal frame should be part of that wiring harness, extending out of the harness.  Perhaps it is tucked into the loom and just needs to be located, pulled out, and screwed down(?).

[greenacres]

Yes I installed a new wiring harness.
There is a black wire with a ring terminal on the end coming out of the wiring harness. It appears to be 18 gauge, and it is about seven inches long. Is that the ground wire for the instrument cluster? I expected that it would be a larger gauge wire.

[bd]

It probably is the ground wire of topic.  If you have an ohmmeter, check the continuity between that black pigtail with the ring terminal and the black wires at the cluster connector.  None of the factory I/P harness grounds are high current, so 18-gauge (or more likely 16-ga) wire is adequate.

[greenacres]

There is continuity between the ring terminal on the pigtail and each of the three black wires at the cluster connector. Thank you for explaining this.

[bd]

You're most welcome.