The Stovebolt Site Forums The Shop Area The Electrical Bay '58 Apache headlight problem

I have a problem with my headlights that has burned off the contact strip in 2 headlight switches. The first problem I found was corroded connectors in the plugs for the headlights and the parking lights. Would corrosion cause the switch to burn out...maybe due to high resistance..???? I'm thinking that with the switch on and the resistance is really high the switch will heat up due to excessive current. Is my thinking correct??? :confused:

Are you running higher than stock wattage headlights? You would be better off using a relay to power the headlights to save your switch.

I dont know the wattage of the headlights. What is stock wattage?? My lights are powered directly thru the headlight switch. How do I connect a relay and what type of relay do I need??

if you're using normal quad lights and having problems with excess current draw you need to find the problem and fix it - relays not required, and in the situation would just be masking the real problem

Bill

Bill's right ... find out what's causing the problem first.

Then, if you want to add relays, check this out:
Click HERE

cjoe,

I don't think a bad connection at the headlight plug would affect the switch contacts. A high resistance connection usually results in heat at that point, and decreased current flow through the system.

Were your light switches both new, and did they both fail in the same manner?

If the lighting circuit is fused before the light switch, and the system draws too much current, the fuse would probably pop.

I think poor contact on the switch points themselves could cause a heat buildup, and subsequent failure. The contacts should be rated for more than enough current if the switch is a quality item...if the switch is from India or Malaysia, it might not be up to snuff.

Stuart

One switch was old and one was brand new. I just recently bought the truck and the lights didnt work at all. I found a corroded plug and after cleaning it up all lights worked but switch was very hot and burned the contact strip. i replaced the switch and had lights but suddenly nothing. i discovered the new switch burned out the same as the first one. I am running 12V, is the switch only rated for 6V???
Switch seems to be quality product not cheap junk

cjoe,

If I understand it correctly, the switch would be rated for a certain amperage at a certain voltage. If they actually were rated, which they probably weren't, the 6 volt switch would be more stout than the 12 volt version.

I don't know what kind of load headlights draw, but the circuit should be fused, and it seems the switch should be rated at least as high as the wire, and higher than the fuse.

What all this means is too much current is flowing somewhere when you turn the lights on.

Try and find the fuse in the headlight circuit..make sure it isn't a penny. See what size the book calls for and install that as a safety for right now.

The least I would do is do some detective work on the harness that leads to both headlight assemblies. You might just turn up a crispy wire mashed under part of the sheet metal.

I guess you will have to replace the switch, so when that happens, you have another chance to troubleshoot the system. Does the switch have a parking light position, then a headlight position. Maybe a pot for dashlights too. You have three sources for a problem. Do each position at a time, let it sit and see what happens. If your proper fuse is in, it will save your $$$ switch. Let the popping fuse be your indicator of trouble.

Don't forget that the taillights are also on this circuit...mashed wires under a truck bed and around the tail gate area are not uncommon.

Good luck!

Stuart

1- tailights all work fine
2- dash lights all work fine
3- headlights..no
4- parking lights...no
yes there is a position on the switch for parking lights
I ohmed the headlight circut and that is how I found the original problem (corroded plug in parking light wiring). I have a question...when ohming the headlights should I get continuity to ground thru each circut (high and low beams)?? That is when ohming thru the headlight bulbs.

the best repro switch will say "Danchuk" on the metal plate and have a small fuse and 2 bi-metal strips - are those strips what's getting fried? they get hot when there's too much current passing thru and open up, like a circuit breaker, closing again when they cool down - getting too hot is drawing too much current, opening and closing repeatedly would arc them to death

Bill

cjoe,

Not sure on the question. The three prongs on the headlight represent two filaments and one common (I think). You should have continuity through each filament tab to the common, or ground tab...does this make sense.

Have you looked at your dimmer switch yet?

I think you will always get continuity to ground, but it must be with a load in the circuit, such as a lamp, or relay. If you probe a wire without a load in the circuit and get continuity to ground, it is a short.

This is what you want to find..a path to ground from a powered wire (not energized) when it isn't connected to its load..a headlight or parking light.

You still need to address the fuse deal, it's your protection and will help you find the problem.

I think this is how it works!!

Stuart

Bill....the switches are Delco-Remy (marked made in USA)..they have small fuses built-in...there are 2 contact strips and it is one of the strips that is burning in half, not the contact points.

Stuart....you explaination helps because when I ohmed the circut I was ohming the wiring and the headlight lamps all at the same time. I had continuity to ground as I expected I should. but I can see now that ..maybe..I am actually ohming a bad wire in the circut that is shorted to ground...hmmm??

one of those contacts is for the headlight circuit, one for the rear lights - if the bi-metal is melting you have an extreme draw on the headlights, like bad insulation on a wire maybe, or a bad dimmer switch as suggested

Bill

I am ordering a new light switch and a dimmer switch. Before I install the new switches I will rewire the headlight circut and locate or install a fuse before the light switch to protect it. I think once I get the issue solved I will wire in relays as discussed earlier in this thread. I want to thank everyone for their input. It sure is great having people to share ideas ...thanks again..........when I find the culprit I'll let everyone know what it was.

All,

It would take a lot of current flow to blow a Delco switch. Especially to burn through one of those contact arms. I'd speculate a dead short somewhere. A bad ground would cause inop lights, but I don't think it'd burn the switch.

Do you have High-Beams? Circuit runs from dash switch to "dimmer switch", then to headlights.

FWIW, I'd use dielectric (aka: "tune-up") grease for electrical connections after cleaning them up so that nasty corrosion won't happen again. I doubt corrosion is the cause of your burnt switch, but it sure doesn't help the flow any.

John

P.S.
Have you compared the connection placement to the switch on your 59? My original switch has a contact marked "PL", but that's for the "Panel Lamps" and that is the circuit the attached fuse on the switch protects.

I bought a new switch, new dimmer switch and new headlight harness. Installed the switch as diagrammed in the factory manual('55-'59 trucks). This is the same setup as the switch in my '59, John. Installed the new dimmer even though all testing (with VOM) showed it to be ok. It was old so I chose to be sure it wasn't a future problem. I did not find a specific problem with the old headlight harness but the insulation was very brittle and the headlight buckets were full of debris, spider nests and other crap that may well have been shorting out the lamps. Cleaned all the crap out, installed new harness and the headlights works great. I will install a 30amp. circut breaker ahead of the light switch in the morning to protect all lighting components against possible future problems....but, I couldn't get the parking lights to work so I removed the fixtures and discovered that the PO had installed the grill with the right side wires underneath the mounting and crushed the wires when tightening the bolts. I rewired the fixture and am still having problems with the parking lights and turn signals because of bad sockets. I am ordering new parking light assys in the morning and also a new stoplight switch . Soon gonna have the old girl 100% and can't wait to get her out and run her. Thanks to everyone who gave advice on this issue. I hope somebody having similar problems gains some help from this thread.