Old Jeep CJ-7 (82) Headlights go out

crackedhead1

Divorce leaves me with the old clunker and I need to make it safer for full-time use. Every time I drive at night, the headlights shut off every few minutes. It seems to be worse when it's warmer, but either way, they shut off six or eight times before staying on for 10-15 minutes. Then I go throuhg the whole cycle again. I have run the wiring diagrams for a short, disconnected wire, etc. My fuel and temp gauges also are out but have been for some time. Dealership where we bought our new Jeep said the guages were shot. I bought new ones and it did not fix the problem.

Back to the headlights, a friend said he had heard of this once and said he was told it was a "breaker" that shuts off. I have never heard of or found a breaker in any of my old manuals.

Any suggestions or ideas would be much appreciated! Thanks.

Mr_Shiftright

Hmmm....could be a couple things.

One would be the headlight relay (wired between the dash switch and the lights themselves). Another would be the possibility that on and old clunker like this someone has changed the source for the headlight juice...maybe there is an old corroded wire coming off the positive battery post?

But a relay sounds very plausible, since it seems to be heat and time related, exactly like a funky relay would act.

crackedhead1

Thanks a lot for your comment. Would that relay be on the engine side of the firewall. I suspect your relay idea is more probable in that I have had this Jeep for 10 years and this problem is relatively new.

Any ideas on the fuel and temp gauges? They are linked on the old CJs and I assume if a ground wire is bad on one, both would be affected (?). I ran a lead to the battery just to see if I could get them to jump and still no go.

I am going to replace the sending unit on the temp first, if that doesn't work, drop the gas tank next time it is low and check the ground wire. I just can't get a good handle on it while it's in place, no room. I have a little dental mirror and can see that it looks to be connected, but it still might need to be cleaned up and reattached.

Any other grounds I could be missing? I hate wiring!!!!!

Mr_Shiftright

The ground strap from the engine to the frame of the car...if that is broken or corroded that can cause all kinds of grief.

crackedhead1

It appeared to be ok, although I pulled it, cleaned it and reattached it earlier this year. Thank you.

crackedhead1

I can't find a relay anywhere along the line from the lights to the switch. Could it be on the switch?

I did find out the parking lamps were old, shot and shorted out a bit. I have ordered new ones but after disconnecting, the headlights still do their same old dance.

jgmilberg

I had an '82 Dodge van did the same thing. Replaced the switch and all was well again. Did the Jeep get rained on with the top off or down a lot? That kind of thing will wreak total havoc on stitches, and wiring.

As far as the gauges go take the temp sensor wire off the sensor, and hook it to a good ground, if the pointer doesn't move it's either the wire or the gauge, if the needle gets buried it is the sender. If I remember correctly the sending unit for the fuel tank on Jeeps are FAMOUS for going out, and the only way to fix it is to get a new sender and drop the tank all the way out. You can test that the same way as the temp sensor.

spokane

I agree with jgmilberg; the light switch is likely to be the problem. Many vehicles have a circuit breaker built into the light switch and the old breaker may no longer be able to carry the normal load of about 9 amps. This breaker serves only the headlamps - the taillamps should be unaffected. Note that there is no fuse because a blown fuse would cause a dangerous permanent loss of visibility. Your hot weather symptom is also consistent with a defective breaker. A less likely possibility is a short to ground in the headlamp circuit, causing the current to exceed the breaker capacity.

The gauge problem is unrelated to the headlamp situation. I'm not certain about the '82, but some vehicles have an "instrument power supply" which may be nothing more than a resistor that supplies the proper voltage (~7 V, I believe) to the instruments. Since both gauges are out, check to see if this unit is burned out. It's probably attached to one of the gauges.

wtd44

I had a '78 Chrysler New Yorker that shorted intermittently. The lights would go out and mysteriously reappear. There was an on-again off-again short occurring in the fat bundle of wires passing through the firewall from under the dash. My agony in remembering this prevents further description... lol

crackedhead1

Thanks for the reponses. I replaced the switch again, it was only a year or two old, and the situation still occurs. As for the guage problem, I am going through Jeep to get a new temp sensor since local auto parts store say, "not available." Bet it will be 4 times higher -- I guess dropping the tank is next. Can't find a resistor on the guage behind the instrument cluster, but it seems to short out other lights when the main cluster isn't touching the mounting screws on the back of the dash just right when I'm messing around with it. Those wires and the main feed wire (temp, gas, 4WD instrument lamp, do not show juice with or without key on.

If I'm lucky, I'll get a good jolt and it will all become clear to me. Thanks again to all who posted.

tupperware2

crackedhead1,
I had the same problem on my '83 CJ-7. I traced the problem to the floor mounted dimmer switch. Hard to believe but this switch can cause all sorts of problems with the headlights and dash lights.

crackedhead1

Tupperware:

I replaced that switch a few years ago because it had become hard to push, and with the floorboard having a little rust here and there, it is possible that I don't have a good ground on it, or the wiring could be cracked or frayed someplace and I know I never really looked for that. I am going to check that out tonight and thanks a lot for your suggestion!