i dont know where to tell you to look.

some one will chime in though.

i think it must be in the wiring that attaches to the instrument cluster. the cluster itself is isolated so it cant be grounding through that. if you look at the repair manual you should be able to find the color code for the wire that is that ground.

but it really sounds like a grounding issue not a guage issue.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.