Auto Electronics: 1981 Cad instrument panel, heater settings, water intrusion

Question
My son has a 1981 Cad Eldorado. Since he got the car (which reportedly has 55k mi on it) the instrument panel display would go blank after driving for a while (2+ hours)... intermittently. Now the problem has changed to the display going blank if you turn the headlight switch on. Pull the switch and all the displays go blank. Close the switch and they all come back on. It only seems to be the power to the light as the display readings stay the same...meaning they don't reset (digital displays)  i.e the AC/Heater settings stay the same.

Any thoughts?..I have access to ALLData but only back to 1982

Thanks,

Bruce Hanes


Answer
Bruce, I do not have a wiring schematic for this year Caddie. The problem you describe however, sounds like a ground issue. I would begin by pulling off any under dash panel and or the instrument cluster to gain access. Check all grounds in the vicinity of the cluster, including the grounds behind the left kick panel. Look for corrosion caused by water intrusion and check for loose connections. Hope this helps. Don.