'70 Olds dash ground

[woz442]

I've got what appears to be a bad ground in the dash of my '70 Olds 442 convertible. When I hit bumps or put the car in reverse all of the dash (radio, lights, convertible top controls, etc) does not work....then will come back once in a while when hitting a bump or something. Before I tear into the dash, any spcific places I should be heading to find this bad ground> I hate to remove all the air ductwork and such if I wouldn't be heading in the right direction. Thanks.

Woz

[rocketraider]

There are several ground straps in the 1970 dash. Three are behind the instrument cluster, for headlights, cluster lights/gauges, and heater/AC control. You can access these by removing the cluster bezel and then the instruments. It comes out from the front.

Another is behind the dash in the radio/ashtray area for the lighter and radio chassis.

All of them attach to the metal lower dash by studs that attach the plastic dash to the metal dash. Make sure the nuts are on tight. You can see them from behind the dash.

Since everything is affected, I'd check the bolts attaching the dash to the car body first, then work your way to the other ground straps. In a convertible, it's possible exposure to weather has oxidized the ground connections or they may have loosened over the years.

One more thot- is car automatic or stick? Sometimes AT cars will ground thru the shifter cable if any of the chassis ground straps are broken or loose. Check all of those- engine to firewall, (-) battery cable to fender, frame to fenderwell. Usually if that happens, the shifter will be very hard to operate or may freeze up entirely. Neighbor's kid had a 4-speed 69 Camaro ground thru the heater control cables once and there was enough current to melt the main cable to where you could not operate it. Sure enough, the kid had been messing underhood and didn't put the engine to firewall ground strap back.

[woz442]

Thanks Glenn! Your tips made finding the problem easy, I really appreciate your help.

Tom