No headlights. . .

[Mike Quillici]

I drove to work today, and my headlights worked. I then drove to a meeting, and my headlights worked. Then I left my meeting, and no headlights. My tail lights work, side marker lights work, high beams work, dash lights work, dome light works, but no headlights.

So, I drove home with my high beams on. Alas. My question, though, is this likely a switch issue? What's the best way to track down this electrical gremlin?

Thanks

[Kurt L]

check your dimer switch,i bought a truck one time and didn't have head lights turned out it was the dimmer switch. it was all corroded[sp] and i put a new one in and had lights it's worth a try.

[Mike Quillici]

The dimmer switch seems to work fine in all regards, except for the headlight function. No flickering or odd operation. But a switch sounds like a cheap fix.
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[19Hoosierdaddies68]

My headlights don't work sometimes as well, seems to be the high beam switch on the floor. right now I just keep clicking it until the headlights come back. Maybe check to see if a wire came loose or fell off.

[MikeyMan]

I would replace the dimmer floor switch and check the plug & wiring that goes to it.

If all you other lights work properly, I would suspect the dimmer connection.

[bobs409]

Try wiggling the plugs on the back of the headlights. (with switch on in low beam) Alot of times there's a bad connection there.

[oklalawnboy]

My vote goes to the dimmer switch.

[mrein3]

If wiggling the plug down by the dimmer switch gets you your headlights back, you have a cheap, easy fix in your future.

Go to NAPA and buy three pieces of part number 725147. You can go to NAPA online and see what they look like.

Go home, unplug the dimmer switch, mark/write down/remember where each wire goes then remove each wire from the connector. There is a little tab on the wire terminal that needs to be depressed with a little flat blade screwdriver to get the wire and terminal out.

Cut off the old, green, furry terminal. Clamp on your new terminal. Insert the wire where it came from. In reality you only need to remember what the "in" wire is to that switch. The high and low can be swapped as the switch doesn't care it just alternates between the two circuits.

I would take this time to clean the male connectors on the switch as long as you got your hands dirty. Brush them clean then apply a little electrical grease so the connection will last another 40 years.

Screw dimmer switch back down and plug in your re-habbed connector.

Done in about 30 minutes and for less than a crappy cup of coffee.

You'll be so happy and in for so little money at this point that I suggest you search this forum for "relay headlight upgrade" and put another $15 or so bucks into your lighting system. (You'll need 6 more 725147 and two relays and some 10 or 12 gauge wire). When done you'll wonder how you drove for 40 years at night without the relays.

[72freak]

Normally its the dimmer switch or the headlight switch going bad. It could also be your connection at your wiring harness block on the cab. Have you had it a part lately?

[Stocker]

Great advice above. Since the high beams works, your dashboard switch is OK, and grounds are also OK. Everything points to either the dimmer switch or a poor connection at the dimmer switch.

[rkn463]

Unless both bulbs burned out the low beam filament at the same time I don't see how it could be anything but the dimmer switch. You should be able to verify with a short length of wire: disconnect the plug, turn on the lights, find the "hot" with a volt meter or test light, then jump it to each of the other two wires one at a time. One should be low beams, the other high.

-Richard

[Mike Quillici]

$20 in replacement parts, and it turns out it was a loose wire. . .

Oh well. I now have a new headlight switch and a new dimmer switch. Thanks for all the help.

[rkn463]

Originally Posted by Mike Quillici

$20 in replacement parts, and it turns out it was a loose wire. . .

Oh well. I now have a new headlight switch and a new dimmer switch. Thanks for all the help.

Just for future generations, where was the loose wire?

[Mike Quillici]

It was a loose wire on the plug to the floor dimmer switch...
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[1969GMCTruck2500]

Great information on this forum!

The topics on headlight problems helped me figure out the connections were bad at the dimmer switch. I was beginning to suspect the headlights themselves and I looked at the ground wires also. I jumped the three wires together at the dimmer switch and all four headlights lit up!

The PO torn up the dimmer switch connector looking in the wrong place for a short in the wiring(I found a short in the alternator soon after I bought the truck). I ordered a dimmer switch and a dimmer switch connector at Rock Auto.

[Magnafyed]

Mistakenly crossed positive and negative posts.

Headlights stopped working.

This forum is most helpful. I had looked to many places.
I am glad I waited to take action..

My issue was also the connection at the dimmer .
Crossing the wires must give just enough energy to create a loss of connection.
Very fortunate that was all it did.
I had already replaced the dimmer.
I just cleaned the gak from around the contacts, installed and removed the plug a few times and carefully applied some dielectric grease to the spades and connector.

Instant headlights !

In the process found a ground for a backup light I had installed that had fallen off.
That works again as well !


Great forum ! The shared info is very much appreciated .

[Oregon 1967 GMC]

I bet it's a loose wire.

[custom10nut]

Clean all your contact, and dab a little dielectric grease on them. Over time humidity causes corrosion build up and a break in contact. Another thing I do is to get some electrical contact cleaner, and spray into the female portion, to clean the hard to get to contact points. One last thing is to check all your grounds. These to are prone to the corrosion phantom