Truck Repair: Headlight going off and on, gas gauge, pink wire

Question
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Followup To
Question -
Headlights are going off and on.  The green lights in the dash (left one for bright lights and right one for running lights) go off and on as well the headlights flash on and off.

Checked the (3) relays in the glove compartment.  Took each one out (one at a time).  When the one on the right side is taken out, this causes the left headlight to go completely out.  Take the one on the left side out and the truck completely dies.  The middle one did not have any effect on anything.  You can hear a clicking noise from the relays. Can't tell which one is clicking.  
The lights start to flash on and off after the truck has been running for a while.
What should we check to eliminate this problem?

Also having problem with gas gauge.  The gauge stays on full all the time when switched on. The only way we can be sure we have enough gas is to set the mileage trip gauge.  Fuses has been checked.  What other suggestions can you offer?


1997 Chevrolet S10
6 cylinder
4.3 vortec
automatic transmission

Answer -
Look in the owners manual for a circuit breaker location. Sounds like it is tripping, then resetting. May be worn out.Van

Van, Thanks for your information regarding the circuit breaker. We will try to find it. What about the gas gauge question?  You probably overlooked it at the bottom.

Thanks again.


Answer
Well, you will need to get to the connector near the tank, and unhook it. There is a pink wire, and a black wire, and a fuel pump wire if it is injected. The black is ground, and the pink goes to the gauge.
Basically, if it is unhooked, the gauge should go to one end, and when you ground the pink wire, the gauge should go to the other end.
If opening and grounding the pink wire has no effect, with the switch on, the pink wire could be shorted to ground, open, or the gauge is bad.
If the gauge works both ways by opening and then grounding the pink, then the sender is bad, or the ground wire isn't connected well.
Find a Motors, Mitchell, or Chilton manual, and look for troubleshooting gauges for step-by-step.
Good luck,
Van