headlight question
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headlight question
I just bought a 1979 f250 and can't seem to get my headlights to turn on. The head lamps worked when I bought it two days ago. I have running lights, turn signals, and all the other lights work except for my headlights. I replaced the old fuse and have pulled the headlight switch all the way out to the extended position. I have also tested the wires on both sides of the fuse box and they seem to be good.
My manual says something about a 18 Amp circuit breaker for the headlights but I can't seem to find it. Not even sure if that is the problem but I am all out of ideas.
Any thoughts?
My manual says something about a 18 Amp circuit breaker for the headlights but I can't seem to find it. Not even sure if that is the problem but I am all out of ideas.
Any thoughts?
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Welcome to FTE. There is no such thing as a headlight fuse, so what is it you're testing?
The headlights are protected by a circuit breaker inside the headlight switch. If you have running lights, then power is at least getting to the switch. Start by disconnecting the headlights and checking for power at the headlight connectors with the switch all the way ON. Low-beams are RED with BLACK stripe.
If you DO have 12 volts on both; then both bulbs are bad. If you do NOT, then there is a problem with the wiring upstream, the headlight switch, or the dimmer switch. It's very easy to find exactly what's wrong by taking it one step at a time; so don't go spending your $20 on something just yet.
The headlights are protected by a circuit breaker inside the headlight switch. If you have running lights, then power is at least getting to the switch. Start by disconnecting the headlights and checking for power at the headlight connectors with the switch all the way ON. Low-beams are RED with BLACK stripe.
If you DO have 12 volts on both; then both bulbs are bad. If you do NOT, then there is a problem with the wiring upstream, the headlight switch, or the dimmer switch. It's very easy to find exactly what's wrong by taking it one step at a time; so don't go spending your $20 on something just yet.
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The headlight fuse I was talking about was fuse number 2. The manual said it was was the fuse to the headlamps among other things. I just check the wires to the headlamps and didn't have any current coming through. I checked the running lights with my circuit tester and they are good. My guess now is that it is in the headlight switch itself unless you have any other ideas?
Welcome to FTE. There is no such thing as a headlight fuse, so what is it you're testing?
The headlights are protected by a circuit breaker inside the headlight switch. If you have running lights, then power is at least getting to the switch. Start by disconnecting the headlights and checking for power at the headlight connectors with the switch all the way ON. Low-beams are RED with BLACK stripe.
If you DO have 12 volts on both; then both bulbs are bad. If you do NOT, then there is a problem with the wiring upstream, the headlight switch, or the dimmer switch. It's very easy to find exactly what's wrong by taking it one step at a time; so don't go spending your $20 on something just yet.
The headlights are protected by a circuit breaker inside the headlight switch. If you have running lights, then power is at least getting to the switch. Start by disconnecting the headlights and checking for power at the headlight connectors with the switch all the way ON. Low-beams are RED with BLACK stripe.
If you DO have 12 volts on both; then both bulbs are bad. If you do NOT, then there is a problem with the wiring upstream, the headlight switch, or the dimmer switch. It's very easy to find exactly what's wrong by taking it one step at a time; so don't go spending your $20 on something just yet.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
You could very well be correct, but why not do some real troubleshooting before telling the guy to spend $20 on something that might solve the problem, no?
As mentioned earlier, this could be a problem with the wiring, headlight switch, or dimmer switch. The headlight switch typically outlasts the dimmer switch, but that's not always the case.
Disconnect the connector on the floor-mounted dimmer switch. You may have to pull back the floor mat. The RED with YELLOW stripe wire on the connector should have power with the headlight switch all the way on. If it does NOT, replace the headlight switch. If there is power here, then either the dimmer switch is bad, or the wiring downstream of the dimmer switch is at fault.
Disconnect the connector on the floor-mounted dimmer switch. You may have to pull back the floor mat. The RED with YELLOW stripe wire on the connector should have power with the headlight switch all the way on. If it does NOT, replace the headlight switch. If there is power here, then either the dimmer switch is bad, or the wiring downstream of the dimmer switch is at fault.
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