Headlight Wiring Help...

1stJeepKJ · **Posted:** Mon Jul 03, 2006 7:07 pm

So, the passenger side low beam headlight has a gremlin in it. It works about 90% of the time and doesn't the other 10%. I've tried to determine a pattern as to why it won't turn on but nothing seems to work. Does any body have any ideas? I've checked the connections and the wiring. It all seems to be OK. My highbeams work just fine. It's driving me nuts and I don't want to take it to the dealer just yet. I know they will charge me a fortune to look at the eletrical.

unixxx · **Posted:** Mon Jul 03, 2006 7:12 pm

Did you check to make sure the bulb is seated properly and doesn't have any corrosion around the contacts?

1stJeepKJ · **Posted:** Mon Jul 03, 2006 7:23 pm

Yeah, at first I thought maybe the bulb was getting burned out and maybe the filament was way thin so I bought new bulbs and replaced them. That didn't fix the problem and the bulb I replaced look in tact. The contacts and everything seem to be fine. The contacts would affect the highbeams as well, I think? and they work fine. Also, if the passenger side is on and I switch to high beams and back, somtimes the low beam won't come back on. Eventually, the low beam always comes on. Sometimes it take 2 min, sometimes 15 +. It's so weird. Is the pax side low beam powered from the drivers side light? I'm trying to get a feel for where, in the wiring, the problem is. And how exactly they're both wired.

I've also checked the fuses inside the drivers side door. They are fine as well.

unixxx · **Posted:** Mon Jul 03, 2006 10:02 pm

The left and right low beams use two seperate 10A fuses, fuses 5 and 4 respectively. The wiring is very simple and the only components between the power distribution block and ground are the low beam relay, low beam fuse, and the actual combination low/high lamp itself. The high beam circuitry is nearly identical, except it runs through a different element in the bulb. You could try replacing the relay, but if the relay affacted one lamp it would also affect the other. Are you sure you tried replacing both fuses? There is also a connector in the middle of the harness that goes between the relay and the lamps that you might want to check.

1stJeepKJ wrote:

Yeah, at first I thought maybe the bulb was getting burned out and maybe the filament was way thin so I bought new bulbs and replaced them. That didn't fix the problem and the bulb I replaced look in tact. The contacts and everything seem to be fine. The contacts would affect the highbeams as well, I think? and they work fine. Also, if the passenger side is on and I switch to high beams and back, somtimes the low beam won't come back on. Eventually, the low beam always comes on. Sometimes it take 2 min, sometimes 15 +. It's so weird. Is the pax side low beam powered from the drivers side light? I'm trying to get a feel for where, in the wiring, the problem is. And how exactly they're both wired.

I've also checked the fuses inside the drivers side door. They are fine as well.

1stJeepKJ · **Posted:** Mon Jul 03, 2006 11:50 pm

Yeah, I checked the fuses. I even switched them with each other knowing that the driver's side worked. Didn't fix it. I guess I'll check the relay and try to find the other connection you talked about. Thanks for the help. I'll let you know what happens.

dslguy · **Posted:** Tue Jul 04, 2006 12:05 am

Check the ground for the right headlight, on low beam the current is lower and a high resistance the ground connection will cause this, going to high beam will draw higer current and overcome the resistance.

unixxx · **Posted:** Tue Jul 04, 2006 12:22 am

Good idea dslguy, never thought of that. The ground eyelet for the headlamps should be bolted to the left inner fender.

dslguy wrote:

Check the ground for the right headlight, on low beam the current is lower and a high resistance the ground connection will cause this, going to high beam will draw higer current and overcome the resistance.

Cowcatcher · **Posted:** Tue Jul 04, 2006 10:49 am

I have a 300Z and when I experience this kind of issue with it (All the time) it is always the mulifunction switch.

unixxx · **Posted:** Tue Jul 04, 2006 12:04 pm

Cowcatcher wrote:

I have a 300Z and when I experience this kind of issue with it (All the time) it is always the mulifunction switch.

In the Libertys everything is computer controlled. The multifunction switch tells the body control module that the driver wants low beams and then the BCM turns on the low beam relay. Both the left and right low beams are controlled by the same relay and BCM output. If one lamp had a problem and the other didn't it would rule out any issues from the relay back. It is after the relay that the circuit for the two lamps splits.

1stJeepKJ · **Posted:** Tue Jul 04, 2006 1:10 pm

That's one of the reasons this is driving me nuts. That it's not happening to both sides and that it doesn't happen consistently or in any discernible pattern. So I guess I'll start from the the lamp and work my way back to the relay. I check the ground as well. If I can't find it I guess it'll have to go to the dealer.

1stJeepKJ · **Posted:** Tue Aug 01, 2006 6:14 pm

I finally took it to the dealer to look at. They found the short. They said it was behind the "Knee Block". I'm guessing that is the area under the steering wheel. They said some prongs or something had warn threw the outer layer of the harness. They charged $90 to fix it. I'm OK with that. Works all the time now and I was able to get the KJ registered.

Headlight Wiring Help...

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