I just went through a quite lengthly diagnosis of a 2001 Cavalier with a flaky instrument panel. The owner complained that, while driving at cruise speed on smooth road, the instruments would all go to rest, like the ignition was off, and all the panel lights would come on.

A replacement instrument panel did not cure the problem. Replaced the ECM, BCM, still had the problem.

It turned out the problem was a bad/intermintent/high resistance ground.

The instrument panel grounds to the metal support structure under the dash. This support structure was not grounded to the car. It seems impossible because it bolts to the car structure but it was not grounded. Tested with an ohm meter and found very high resistance to the body.

Installed a ground wire from the support structure to the engine block and everything worked normally and has for over a month now.

A second Cavalier starting to exibit the same symptoms was tested and the dash support structure had high resistance to the body; not a good ground.

A ground wire cured this problem also.

Maybe this will save someone a lot of time and money.

Verle