M38Cdn Refurbishment

[rob love]

The gauges take their ground thru the case, or for the later plastic housed gages, thru the clamp and onto the studs on the back of the case.

Many guys test the gages on the bench by putting power to the power terminal and full negative onto the sending unit terminal. The results are usually quick and not good....you need the case grounded. Cheap insurance for any M-series vehicle is to run a ground wire from one of the screws for the panel lamp (use a longer screw than original so you can get a ring terminal, a couple of internal tooth lock washers, and a nut onto it) and run the ground wire to a screw behind the dash, such as the screws holding the circuit breaker in place. You can put a set of Douglas connectors in between to make it easier to remove the complete panel if that day ever comes, or leave it as a solid wire.