Headlight Question

[W.F. Brown- III]

The headlights on my '48 Special Deluxe have stopped working. Please help me think through and troubleshoot the potential problem.

The lights had been working, but when going from low to high beam "hesitated" (if on low, would go out when dimmer switch pressed, then would come on bright). Now, nothing.

The car has been rewired at some point prior to me getting it (old rewire job, probably in excess of 30 years ago I would suspect). The system is still 6 volt. The lights have been run through a headlight relay switch.

When the main light switch is pulled out, the running lights work, but the headlights do not. The indicator light for low/high beam works fine when the dimmer switch is pressed.

Could the dimmer switch be the problem, even though the high/low indicator works?

Or, is the likely culprit the headlight relay?

Thanks in advance for your help.

[BobT-47P15]

Sounds to me like the dimmer switch.

In the past, some have suggested stepping on it (to work it)

numerous times. Sometimes that can result in better contact.

Otherwise, a new dimmer would be the first thing I would try.

I don't have a relay in my P15.

Also, did you check your connections on that little bar on the front

of the inner fender to be sure they are nice and clean?

[greg g]

Bob mentioned the two most likely problems, the third is the 30 amp fuse that is part of the headlamp switch. Usually if that blows you will have no lights, as parking lights, brake lights, interior lights, as well as head lights are protected by that fuse.

Your mention of the hesitation between high and low beams directs me toward the dimmer switch.

Also as that switches terminals are exposed to the elements below the floor boards, they may have also corroded enough to cause resistance.

AS noted, cycling it through a few hi low stomps can most times clean up the internal contacts.

[W.F. Brown- III]

Thanks for the replies. I read up on numerous post about "headlights", and learned quickly about the trick of working the dimer switch numerous times. So far, this has not worked to correct the problem. I also checked the fuse at the light switch, as well as the two fuses at the headlight relay. They all are good.

I guess the thing that is throwing me (being "electrically challenged") is the high/low indicator light works fine as the dimmer switch is pressed.

Would the high/low indicator light have any relevance to the proper working of the dimmer switch in respect to the headlights? In other words, if the high/low indicator works is the dimmer switch working, and, therefore, should I be looking somewhere else for the problem?

[austinsailor]

You can easily check if voltage is going through the dimmer switch with a cheap volt meter. Check the input to make sure voltage is getting to the switch, if it is then check the outputs. You could also pull the wires off and bypass the switch to see if the lights come on. I agree it's the most likely problem.

If it is the switch, get some spray electrical contact cleaner and spray it in the switch. Keep spraying and working the switch (much easier if you remove it from the car) until it works ok.

[Merle Coggins]

I don't know how your relays are wired but I suspect something is up there. I agree with you that if the high beam indicator lights up than there is output from the dimmer switch, at least in high.

You say that the fuses are good at the relay but are they getting power? Also check the ground for the relays.

Merle

[greg g]

I would check the connections at the terminal bar on the raddiator support. In its position it can become corroded. What needs to be checked is not the screw on the termonal but the interconnections between the wire ends of the wires where they come together.

[deathbound]

Have you checked the contacts @the headlights?

[DCurrent]

I agree with most. You need to check that you have juice from the switch first. Use a test light on all the contacts on the backside of the switch. At some point cycle through the switch and all contacts should have power at one point or another. If they show juice then follow the wiring through to the bulbs checking the juice along the way. You will surely find a bad connection along the way.

My bet is the high low switch is bad. Seems I read not long ago that the switch has a separate contact for the high beam indicator and the source for the high beam headlights. If thats the case they are on separate contacts and one could be on without the other.

Darren

[greg g]

when you say the fuse is OK did you check it for continuity or jaut do a visula check of the metal strip? I mention this because I have had a couple fuses fail that looked fine but did not pass current. Apparently they got hot enough to effect the flow with out actually blowing the current strip.

[W.F. Brown- III]

After spending most of the day checking, rechecking, taking apart and cleaning points of contact, I think the problem is the relay. The lights will work when hooked direct to the power side of the relay (so the lights themselves are good and the relay is getting power). When looking very closely at the relay with its cover off, when the light switch is pulled, one of the contact points will activate. When the dimer switch is depressed, the other contact point in the relay will activate. Therefore, it would appear that the main light switch and the dimer switch are both working. That only leaves the relay itself.

I tried cleaning the contact points of the relay, but that didn't help. I'm not sure exactly how a relay actually works, but I have checked, tightened and cleaned all apparent "user serviceable parts" with no luck. Next step is to find a new relay, or just hook up the lights direct with a separate switch (with fuse).

[DCurrent]

If I'm not mistaken it did not come with a relay in the first place to power up the lights. There is no harm in having one, but it is another thing to go wrong when they fail. Such as now!

Darren

[Oldguy48]

If replacing the relay cures the problem, it might not be a bad idea to keep a spare in your tool kit.

[bamfordsgarage]

...Seems I read not long ago that the switch has a separate contact for the high beam indicator and the source for the high beam headlights. If thats the case they are on separate contacts and one could be on without the other.

I went through this last night on my D25. The dimmer has one terminal for high beams. Two wires meet at one connector here — the thiner wire goes up to the high-beam indicator and the heavier wire goes forward to the headlights. If you have high-beam indication, the problem is not in your dimmer switch.

[Greenbomb]

Be sure to check all the grounds. That can drive you bats!