The vehicle is a 420 SEL, W126 1986 version. The oil pressure gauge on the instrument panel has gone goofy.

The needle remains pegged out on 3, while the vehicle is sitting in the driveway and the ignition turned "off".

While still sitting, when the ignition key is once again turned "on", the needle drops down to between 1 and 2. It then immediately pegs out on 3 when the engine is cranked.

While driving the car, the needle never comes down from the 3, at idle or any other time.

With the engine shut down, and the ignition turned "on", I have detached the wire from the oil pressure sender switch and grounded it to the frame and then removed it. When grounded, the needle pegs out on 3 and then when I remove the ground the needle remains on 3, even though the wire is still unattached to the sender switch. At no time will the needle fall to "0".

Any thoughts would be appreciated.

William