'83 gauge gremlins

[leadmine]

'83 Caballero.Neither the coolant temp. gauge or the oil pressure gauge have ever worked very well:

Replaced oil pressure sender (for gauge) and gauge worked well for a few days and then pegged beyond 60 pounds as soon as ignition turned on; the indicator needle remains in that position. Tried disconnecting connector wire, and, grounding the wire - same result. Replaced the sender again, pulled a new wire from the sender to the printed circuit connector, bought reman gauge cluster. No change.
Same thing for temp gauge, except that it doesn't/never did register any temp change. Same replacements as above.

There is evidently some circuit problem beyond these two gauges, but I don't have a clue where or how to start testing. All suggestions will be greatly appreciated. It would probably be easier to install aftermarket mechanical gauges but I'm not throwing in the towel yet.
Thanks, leadmine

[Scottm]

Have you tried the ground straps from engine to chassis? I just installed mechanical gauges since mine has idiot lights. I left one ground off and they all went hay wire. Also how aboout your printed circut?
See mine has a broken strand wich is the ground lead for the oil light.


Hope that helps