1988 Ford F-250 My headlights are not working

  • 1988 FORD F-250
  • 108,401 MILES
Hello. I just bought a 1988 Ford F-250 5.8L 4x4. The running lamps, tail lamps, and brake lamps all work. My headlights, however, do not. I check the bulbs, and they looked fine. The fuse under the steering wheel was fine. I am not sure what to look for as far as wiring.
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Saturday, June 1st, 2013 AT 1:19 PM

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If both the low and high beams are dead, start at the head light switch and test for voltage coming in. There may be two different power feeds. (I'm doing this from memory). The feed for the head lights will be one of the fattest wires.

Check that connector for signs that it melted or two terminals are black from overheating. Also look at the rivets that hold the terminals on the switch to see if any of those are black and crispy. We'll discuss that repair if you find a problem there.

Next, there must be another fat wire that has 12 volts only when you pull the switch all the way out to the headlight position. If you don't find that on one terminal, replace the switch. Don't confuse the tail / running light terminal. That one will get voltage when the switch is pulled just halfway out.

If you find 12 volts on that second terminal, head to the dimmer switch. Look for the same color and gauge wire coming in and check for 12 volts there. Check that switch too for burned terminals. If you have it there, either look for voltage coming out on one wire in low position and a different wire in high beams. You can also measure the voltage at one of the headlamp plugs. If you have voltage to one of the terminals and the bulb is good, you have a bad ground wire. Typically there's a ground wire on each side so for both head lights to not work you'd have to have two bad grounds. That's not likely. The signal and running lights share a ground wire with the head lights at each corner so those wouldn't work either.
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Saturday, June 1st, 2013 AT 8:15 PM

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