Headlights problem on XJ 1992

Do you have aftermarket bulbs in the lights?

If the lights draw too many amps without a relay, they will blow a circuit breaker inside the headlight switch. Once this breaker has been popped, it doesn't ever hold full power after.

The main ground is a wire mesh strap from the engine head to the firewall.

If you follow the headlight wiring, at the end near one light you will find a black wire bolted to the fender or grill. This is the main ground.

The headlight switch has a ground wire under the dash near the steering column.

Mike

Davey wrote:

The clue that I twigged on was "connection on headlamp switch (tan colour wire) was a little bit melted". Something made that connection hot, either over-load or corrosion. He says that he's replaced both the light switch and the headlamp dimmer switch, it would be good to know if this problem was the reason he changed out the switches or if there was something else going on. Either way it sounds like he's tripping the breaker, it doesn't seem likely that a bad ground is going to cause that.

I am thinking the same thing and I was implying once tripped, the breaker will never be stable again.

I was thinking he tripped the new one before he cleaned up the wires maybe?

Mike

Lee Ayrt>

I hadn't known that about automotive breakers, but I should have guessed, thanks for the tip. Regular AC breakers get weak if they get cycled, but it takes quite a few cycles to soften them up to the point that you'll notice.

Dunno. I'm hoping that he comes back and gives us more detail.

It takes a pile of heat to pop them, usually enough to melt things and the wires are 10 ga. so that is a serious draw.

Mike

Lee Ayrt>

Here I am. I 've just checked everything again and like Mike said, on left inner fender I found ground connections - three of them, little lower down just near left headlight - a bunch of connections and removed all of this, cleaned everything (with good old WD40) and tried to drive around almost half night. Nothing happened. Seems OK. Now I remember after one hard day for my rig somewhere in very muddy terrain I washed Jeep underneath and engine also (mud was everywhere), maybe some connections were corroded or, I don't know... I'll see next few days what will be but seems that everything is fine. One more question: This wire mesh strap which is hanging from firewall should be connected somewhere on cylinder head? I found it just hanging, not connected. Now it is temporary bolted on intake manifold. Probably previous owner forgot to connect again after doing some repairs. Seems to me like I can connect this back on bolt which holds fuel rail. I couldn't find any other ground connection from engine to chassis, strange. Anyway, thank you very much for advices, many greetings from far Croatia.

Davey did pass the time by typing:

That's your engine ground strap. Without it your engine gets it's ground through the drivetrain and that can cause all sorts of sensor problems, rough idle, etc. It goes back to the block. On the 93ZJ it uses the same bolt that holds on the ignition coil, not sure about the 92 XJ.

Holy crap!

Man you are some lucky, that ground strap is the main one for the body. It controls the lights and the ignition computer.

Your body tub was stealing ground from somewhere else which can happen, but normally when that strap goes, the engine dies and you have no headlights. I have seen gear shifts and gas pedal cables be the conductor... Also 2 way radios or stereos depending on their wiring.

That strap is supposed to go on the last head bolt, but if you have a good connection on the manifold, just leave it.

That might be all the trouble.

Mike

Davey wrote:

Guys, thanks a lot. Everything is fine now. This ground strap was a problem.

Something else is bad. It happened again... I don't know what else to do.

I found a culpret on my mom's old Grand Marquis, might be applicable. Seems the alternator connection was a little corroded and that was causing some AC on the voltage. Removed the connectors, cleaned them, and put them back. Probem went away.