Ok my Headlight switch failed, I went to NAPA and picked one up got home put it in and it instantly got warm to the touch. Is that normal for a new switch?

I was worried about it gettin hot and toastin the truck, so pulled the plug on it and came in to post this.

Any input would be greatly appreciated

Keith

 

Keith, it's not unusual for a headlight switch to run warm. It is unusual however for it to happen instantly. What caused the switch to fail in the first place? Heat indicates one of three things is happening. First is something in the lighting circuit may be shorted to ground. Second is there is more resistance in part of the circuit than should be. Third is the circuit is overloaded.

Here's a few suggestions of things to look for.

Bare, chafed, smashed wiring. Places where wires pass thru sheetmetal or frame crossmembers are my usual suspects for this kind of damage. Also a light socket full of water makes for a nifty short circuit.

Corroded connections drastically increase resistance. Since these trucks were underwired to begin with corrosion can make big problems.

Extra lights added to a system that was pretty much strained when it was built draw more amperage than the system can handle. 5 added cab lights isn't a problem. Lots of extra marker lights or adding a trailer without adding relays is.

 

OK thanks, and i am not sure what caused it to fail the first time. I am more than likely going to start tracing the problem.

And i was planning on rewiring it also. so what size wire would you suggest? And i am going to add some relays to take some load off the light switch.

 

Usually the first symptom of a light switch failure on these trucks is the headlights will go off and come right back on. This is caused by an internal circuit breaker that is built into the switch. Each time the breaker trips it gets a little weaker. It doesn't take long until the breaker will no longer reset and the headlights won't work at all.

I don't know how bad the wiring in your truck is but after 35+ years a lot of these trucks have had their share of poor quality wiring repairs. Butchered is the term I like to use.

The headlights were originally wired with what looks to be 16ga wire. This was marginal to begin with. What does help here is to add a relays for the headlights. One for low beam, one for high beam. They can be mounted on the rad support and utilize the original headlight wires to turn the relays on and off. I like to use 12ga wire but I wouldn't use anything smaller than 14ga.

If you have some type of fog or driving lights these should be wired thru a seperate relay.

Trailer lights also should be wired thru relays. This not only helps the life of the light switch but also takes a lot of strain off of the turn signal switch. The lights will be brighter too. Here again I'd go with 12ga wire.

Something you'll have to take into consideration is how to power all the relays you plan to add. I've seen many vehicles with wires added to the battery terminals or the feed post of the starter relay ( often called the solenoid ) on Ford products. Rather than creating potential problem areas I have a suggestion. Mount the relays together as a bank and run one or two wires from the feed post of the starter relay to power all of them. The inner fenders have several places that could be used. I would use 10ga wire for the relay feeds. Also don't forget to add a good ground for the relays.

 

OK thank you so much

 

Also, to add to Redcat's comments, don't forget to use a fuse or circuit breaker on the feed wire(s) to relays.

 

Thanks for catching that 68horses

 

ok new problem =(

4 way flashers work but turn signals do not what would cause that?

Turn signals just come on and stay on. But flashers work fine

 

These trucks used seperate flashers for the turn signals and 4 ways. Chances are the turn signal flasher has failed. They are both under the dash but I don't remember where. To figure out which is which turn on the 4 ways and grab the flashers by hand. The one that's clicking is the one for the 4 ways.

 

Yep the one clipped behind the angled piece is the 4-ways and the one on the back of the gauges is the turns signals.

Both working now.

Oh and the switch is no longer getting hot.

Went all the way around and pulled the bulbs out and cleaned all the connections with a tiny wire brush and they work with no problems.

and once again thank you for all of your help.

Keith

 

Keith,
I forgot to mention, don't be tryin' to use halogen or high powered headlamps with this old wiring unless you do the relay setup. They draw more power and will burn up wires and switches.
Gene

 

thanks, i want to do the rewiring.

Cause not to long ago my cousins truck caught fire. If i remember correctly it was a 74 F150.

 

I have a problem like that but other way around my signals work but 3 flashers work the one on drivers side dont flash when the 4 ways are on

 

now my turn signals Flash really fast ahhh
this is so aggravating

 

Check to see if one bulb is burned out or not connected on the side that flashes quickly. Usually when a bulb bites it, the cycle time will speed up considerably.

If the hazards also flash quickly, you might have both turn signal bulbs out in the front or the back, or one of each.