Headlight switch hot

[87mj]

Hi, I have a 5/71 that lost a headlight.  I replaced it with a fairly inexpensive standard 60w replacement.  While I was driving, I noticed the headlight switch was getting hot (slight heat/smell/smoke over the steering column) so I shut them off. It is a low mileage car so rust hasn't worn any connectors.  To my knowledge, none of the electrical has been opened up in any way.

I was curious what my options are.

I saw that MSA sells a headlight relay harness.   HID looks fairly complicated but should draw less current.  Any recommendations?

Is my switch toast now?

Thanks in advance.

Gary

[Captain Obvious]

Hot switches are never good. Hopefully you caught the issue before you really smoked something.

Get yourself some headlight relays quick, and hopefully you won't have to go deeper than that. You may need to have the switch disassembled and repaired too though.

[grannyknot]

Your switch is probably salvageable, the electrical switches in cars from this era actually need to be used to keep them in good order, moving the switch cleans the contact area.

If I were in your situation I would clean all the terminals from the headlight itself right back to the switch with special attention to the grounds. There are a few good How To threads in the archives on dismantling the switch and cleaning it, it is also the only way to know how bad the heat damage is.  After you get the headlight system working properly again you might want to have a look at the rest of the terminals, grounds and switches in the rest of the car, they have had the same lack of use so probably have the same amount of oxidation on them.

[Namerow]

Don't forget to check the condition of the connector terminals in the male and female plugs that join the headlight's wiring pigtail to the front wiring harness.  These can get corroded.  Each plug has three wires/terminals:  hi-beam, lo-beam, and ground.  Try to clean both the male (easy) and female (not so easy) terminals.  A shot of 'De-Oxit' electrical contact cleaner will help, but use of a small, thin flat file (hobby shop item) will be better.

[rcb280z]

And Zs-ondabrain will rebuild your switch if you don't feel comfortable doing it yourself. He is a member here, just do a search for Zs-ondabrain.

[Zed Head]

I've had the hot switch on my 76 car.  You can peel the tabs back on the switch itself and take it apart.  The heat comes from dirty contacts inside, if you don't add relays you pretty much have to take it apart.  The contacts get pitted after a few million cycles.  The switch is probably fine for relays but might never be good for extended full power.  I added a single relay in front of the fuse box for my problem but the 71 wiring might be different.  Check the diagrams.

http://www.classiczcars.com/files/

[Darrel]

If the switch got hot, then also check the fuse block, in  particular the parking light fuse area. The old fuse blocks are riveted together and cause a lot of resistance making the wires hot.

David Irwin(zondabrain) designed and makes the headlight harness and parking light harness and sells to MSA. Buy both the headlight harness and parking light harness. I prefer to deal directly with Dave.

[Xenn]

Basically everything everyone else said here, a hot switch is because of too much resistance in the system, if you get a relay harness it bypasses the switch for a power supply to the headlights and it basically becomes an on/off switch, making it so you dont really need to clean it. If you clean every connection from the battery to the switch to the headlights and back to the battery you wont need the relay, though it helps if you want to upgrade your lights to something with a higher draw.

In addition to cleaning the switch and harness connecters if you go that way, I recommend you wire brush the metal tabs the fuses contact in the fusebox, I was melting fuses because mine was so corroded.

Also the harnesses are super easy to set up, you basically run it from the battery to the headlights then plug one of the headlight plugs into it so it knows when to turn on/off.