Author Topic: Headlight Dimmer Switch  (Read 4804 times)

Offline ssapach

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Headlight Dimmer Switch
« on: October 16, 2011, 10:15:00 AM »
While dealing with a headlight issue recently, I had to look in the Haynes manual for a wiring diagram for the headlights on my 1986 truck.  I just had to look because on the truck itself I didn't notice any fuses, relays or breakers for the high or low beam headlights.  The Haynes manual shows me the same thing, power through the hi/lo selector switch to the headlights and that's about it.

Am I losing it or is this right?  No fuses or any other circuit protection?

Just for the record, here is the issue I was dealing with:

I replaced all 4 of the sealed headlights with some new housings that allow me to use a 9007 style bulb.  I found out that high beams were too much for the switch and the lights would flicker on and off but low beams on their own were fine.  I pulled the plug out of the dimmer switch and just used a jumper wire so I could check amperage.  It was running about 8.5 amps with low beams and about 18.5 amps with high beams.

My solution was to just put in a relay for the high beams.  Now my current draw is right around 10 amps through the dimmer switch with my high beams on.

The problem got solved and everything is working alright now, but I just found it odd that there are no fuses, relays or breakers or anything like that for the headlights.  Is the dimmer switch built to act as the circuit protection for this?

Offline Captkaos

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Re: Headlight Dimmer Switch
« Reply #1 on: October 19, 2011, 05:23:32 PM »
The way you found it is how it was wired from the factory.

Offline Irish_Alley

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Re: Headlight Dimmer Switch
« Reply #2 on: October 19, 2011, 09:18:34 PM »
i thought there was a fuse for the headlights
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline VileZambonie

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Re: Headlight Dimmer Switch
« Reply #3 on: October 19, 2011, 09:44:10 PM »
The only thing that is not circuit protected is the positive battery cable going to the starter solenoid. Everything from there and beyond should have adequate circuit protection. If you are upgrading the headlights do the right thing and install a relay control. You'll have better intesnsity as well from avoiding unwanted voltage drops.
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