gregglee

My 2001 F-150 instrument panel has an intermittent failure of three gauges: Tach, voltage and engine temp. They are the ones on the right half of the panel. No other gauges and no indicator lights on the panel are affected. Nor is the odometer.

All three are affected simultaneously . Either they all work normally or they all read zero. Sometimes there is a transition period when they all jump back and forth between zero and correct reading.

That they are all affected together and that they are all in the same part of the panel, suggest that the problem is an intermittent open in a shared power lead. I suppose it could be a shared ground but seems less likely to have only three sharing. The signal inputs come from different sources so wouldn't seem to interrupt all at once.

Any thoughts on where to look?

[Done] When I bought my Service Manuals years ago I either overlooked the Third volume: Wiring Diagrams or misplaced it since. Suggested source?

Do the wiring diagrams include PC board layouts? Seems like that could be where the intermittent open is located.

gregglee

One down. I found the original wiring diagram manual on eBay.

gregglee

If anyone cares, I found the problem. Apparently a field mouse had come in from the cold to "nest" behind the instrument cluster. Some fluid, probably urine, had seeped between the circuit board and the plastic back to corrode conductor strips along the bottom edge of the board. I found one open, and another intermittent open.

I bridged the opens by soldering 22 gauge wire connection between existing solder points on each side of the breaks. I did four total since two more passed continuity, but looked as bad as the opens.

Everything works now.