HELP! Healdlights just died

[yoda-g3]

So I'm driving along in my '71 40 on a nice smooth dry road with my lows on for about 20 minutes. I finally get rural and tap the high beam selector on the floor and BAM no running lights, headlights, or dash lights. Brakes and blinkers work fine. I pulled over and checked the fuse block by the gas pedal and everything looks fine (no blown fuses). I haven't done any recent work or upgrades and the system has always been solid. My thoughts so far:

- Not the dimmer switch since I didn't touch it and no bumps at the time of the 'blow'.
- Not an obvious short since the fuse didn't pop. (Unless there is a secondary fuse location I'm missing.)
- Maybe the high / low selector since that's right when it died? How common is that?

It was pretty sweet limping home with my one good fog and a flashlight... I need to get this fixed ASAP as I have for sale in the paper this weekend.

 

[Roundeye]

So I'm driving along in my '71 40 on a nice smooth dry road with my lows on for about 20 minutes. I finally get rural and tap the high beam selector on the floor and BAM no running lights, headlights, or dash lights. Brakes and blinkers work fine. I pulled over and checked the fuse block by the gas pedal and everything looks fine (no blown fuses). I haven't done any recent work or upgrades and the system has always been solid. My thoughts so far:

- Not the dimmer switch since I didn't touch it and no bumps at the time of the 'blow'.
- Not an obvious short since the fuse didn't pop. (Unless there is a secondary fuse location I'm missing.)
- Maybe the high / low selector since that's right when it died? How common is that?

It was pretty sweet limping home with my one good fog and a flashlight... I need to get this fixed ASAP as I have for sale in the paper this weekend.

Wow. Sometimes we find a headlight switch that has a built in circuit breaker in them but it sounds like a definate short.

 

[FF LC FREAK]

The high/low floor switch is known to have problems. Take it out, clean it up and see you can get it to work. That is where I would focus my attention.

Good luck!

 

[allan man]

X2 on the switch,that happened to me last week but the park lights,fuse was good , i good way to rule out the problem is to by pass the switch.hope this helps.

 

[Coolerman]

Check the following:
Double check the 20 amp headlight/marker light fuse. Clean the clips holding the fuse and the fuse itself. I would just replace the fuse anyway AFTER cleaning the clips.
Check the headlight switch. This is the only other component (except a wiring short somewhere) that could take out both the headlights AND the marker lights.
Unless the high beam switch failure involved a short to ground (blowing the 20 amp fuse or due to corrosion causing the contact with the fuse to be lost) it's failure would not have caused the marker lights to go out.

If you want to take your high beam switch apart and 'fix' it go here:https://forum.ih8mud.com/40-55-series-tech/230731-dimmer-switch-tech.html

 

[WES1977]

Check the following:
Double check the 20 amp headlight/marker light fuse. Clean the clips holding the fuse and the fuse itself. I would just replace the fuse anyway AFTER cleaning the clips.
Check the headlight switch. This is the only other component (except a wiring short somewhere) that could take out both the headlights AND the marker lights.
Unless the high beam switch failure involved a short to ground (blowing the 20 amp fuse or due to corrosion causing the contact with the fuse to be lost) it's failure would not have caused the marker lights to go out.

If you want to take your high beam switch apart and 'fix' it go here:https://forum.ih8mud.com/40-55-series-tech/230731-dimmer-switch-tech.html

Yeah, I used to have to reach down and wiggle my fuse while I was driving sometimes.

 

[yoda-g3]

Thanks!

Good place to start. I like the idea of just bypassing it to narrow it down. Safe to assume that there should be three posts on mine, one hot, one high, one low?

If I were to get a new switch for sake of time. What am I looking for exactly? Is it just called a dimmer switch? I got the impression that was what the 'pull out on / off' knob was called.

 

[Coolerman]

The dimmer switch is the floor mounted switch you push with your foot. SOR carries them, or any three terminal floor mount dimmer switch will work.

To test it, turn the headlight switch on, and on the dimmer switch, jumper from the B terminal (red/white) to the 1 terminal (Red/yellow) or 2 terminal Red/green). The lights should come on. If they do come on, but don't with the dimmer switch, replace the switch.

If they don't come on, jumper from the battery to the 1,2 teminal. If they come on then, it's the fuse or headlight switch.

 

[Trollhole]

Could be something as easy as a bad ground. I'd check that before I do anything else.

1st check for 12v with the light switch on. There shoud be 12 at one of the legs of the bulb socket. Make sure you use the ground from the battery.

On trouble shooting I always start at the end source and work my way back.

 

[1979fj40]

Yeah, I used to have to reach down and wiggle my fuse while I was driving sometimes.

x2 , lights would go out and i would have to wiggle it. Waiting on a new blade type box to come in.

 

[FJROME]

Once in a while, if i don't press hard enough on the dimmer switch, instant darkness. stomp on it again and the lights come back.
Hope you find the problem soon !

 

[yoda-g3]

Haha, you're going to LOVE this moment. Turns out it was a fuse. It was a lite 'pop' down inside the cap of the fuse. I didn't see it at night with my flashlight, but sure enough in the daylight I could barely make out a little scorch mark. I 'm used to the entire center of the fuse going so I wasn't looking that closely. Stole my horn fuse and I'm back in business.

Thanks for the help!

 

[John Smith]

Haha, you're going to LOVE this moment. Turns out it was a fuse. It was a lite 'pop' down inside the cap of the fuse. I didn't see it at night with my flashlight, but sure enough in the daylight I could barely make out a little scorch mark. I 'm used to the entire center of the fuse going so I wasn't looking that closely. Stole my horn fuse and I'm back in business.

Thanks for the help!

Fuses typically just don't blow for no reason. Have you engaged the hi-beams yet with the new fuse? Don't be surprised if it blows again until you find the resistance or short. Make sure your fuse block contacts are clean, they can cause enough resistance to blow fuses all day long. BTDT.

 

[WES1977]

Fuses typically just don't blow for no reason. Have you engaged the hi-beams yet with the new fuse? Don't be surprised if it blows again until you find the resistance or short. Make sure your fuse block contacts are clean, they can cause enough resistance to blow fuses all day long. BTDT.

agreed, I had enough resistance in my block to melt the lower section on my fuse block.