Greetings all. First post. I'm working on a "free" van, 78 E150, been sitting about 10 years so all that comes with that is happening.

​​​​​​Issue #356- When I turn on the headlights, the gauge needles quit. Well to be fair only the 2 gauges that currently work (oil pressure & temp) drop out. They work fine unless I turn on the headlights. I have dash lights still. I replaced the headlight switch and no difference.

Thanks in advance.

Chris

 

The older vehicles had a voltage regulator located on the back of the dash panel which supplied power to the dash gauges. It kinda looks like a little metal circuit breaker.
If you carefully remove the dash gauge assy ,you should be able to see it. I would suggest you start with measuring the voltage available at the unit and see if you are getting anything coming out of it


On some of the older vehicles you had to disconnect the speedometer cable to get the dash out. Sometimes the cable was secured in the engine compartment and a clamp needed to be removed so you could get to the cable under the dash.

 

Thanks! I'll check for that voltage regulator!
Chris