I have a 1978 F-150 4x4 short bed and I’m having instrument panel problems. Headlights off my water temp gage goes nearly to “hot”. With my headlights on, both fuel gage and water temp go full high. Any ideas?
Ed

 

I'd guess a bad ground to the instruement panel

 

Agree with Beartracks, but I would look for bad ground in other places too. Did this just occur out of the blue or some work done on the truck recently??

 

It kind of just appeared with no other maint

 

Check grounds as above, but also check output from the CVR, a small transformer attached to the back of the cluster. Also, I have heard of a bad radio resister causing weird issues.

 

Do look see if there is a ground strap/wire, back of engine to the fire wall. As the neg battery cable is attached to the engine block, the sheet metal of the truck needs a good connection to the engine to complete the circuit's back to the battery. When a good connection is lost or poor, the circuit will go looking for another ground source, even travel back to and thru other circuits seeking a ground, screwing up other things. Cap

 

That ground issue makes sense, given the association with headlights, perhaps also check headlight ground.

 

The instrument cluster backs used on: 1973/79 F100/350, 1975/80 Econoline & 1978/79 Bronco were made of a composition material that can turn to dust before your very eyes!

In 1981, Ford came out with hard plastic cluster backs for Econolines. These were also the "service part replacements" for the POS cluster backs.

There are two types:

E1PZ-10848-A .. Hard Plastic Cluster Back - Use with Oil & Amp Gauges / Obsolete

E1PZ-10848-B .. Hard Plastic Cluster Back - Use with Oil & Amp Warning Lamps / Obsolete

CARPENTER NOS PARTS in Concord NC has dozens of each. 800-476-9653