tnovell

I just purchased a 1992 Cherokee Briarwood and the tail lights haven't worked since i got it.

Things I've replaced -

Fuses - the visibly blown ones
Head Light Switch
Brake Light switch
Blinker Relays

I checked for voltage at the plug located in the rear drivers side quarter panel that feeds the rear left lights. I get 12V for the blinker light and brake light (when applied) but no voltage for the tail lights (when the head light switch is turned on).

The dash lights work, the running lights in the front work, and the reverse lights work sometimes. The horn worked for a second but no longer works.

The buzzer in the fuse panel makes a weird crackling noise as it buzzes.

There seems to be a bad ground on the rear drivers side turn signal as well. It goes on and off as I wiggle the tail light housing. The ground wire feeding the rear left turn signal was completely melted to bare wire. I wrapped it in electrical tape for now.

The PO had a wire running from the front marker light to the rear tail lights as a fix. Possibly this caused a short somewhere?

The PO had an aftermarket radio installed as well. I've since removed it.

The wire the feeds power to the Rear Tail Lights is Blue/Red.

I checked for voltage at the headlight switch harness for the BLUE/RED wire and it reads 0V (with the switch On and Off). I checked for continuity between the RED/Blue wire on the headlight switch harness to the RED/Blue wire on the taillight harness in the rear quarter panel and it beeped that it had continuity. It also beeps when i touch the RED/BLUE wire in the rear tail light harness with the nearby ground...does this mean a faulty ground somewhere?

I ran 12V to the RED/BLUE wire on the headlight switch connector and still got a reading of 0V back at the RED/BLUE wire on the tail light connector in the rear drivers side quarter panel.

I've inspected the headlight switch harness and it appears to be good and clean.

Could this be caused by bad light sockets?

I ran 12V to both rear light housing and got all of the lights to come on, including the tail lights.

Should I be getting continuity across the parking light fuse port when the headlight switch is turned on? ..because I am.

The next things i am going to check / replace are :

Steering Wheel Clock Spring
Multifunction Switch
Neutral Safety Switch
Look for Broken Wires in the lift gate that feed the license plate light.

Any insight would be very appreciated.

Cheers,

-tom

cliffy

Set the meter to ohms not beep and check between the blue/red wire and ground again if you see anything other than OL it wouldn't be a faulty ground it means the wire is grounded.

tnovell

Thx for the reply cliffy.

I took a reading at the back taillight assembly connection (blue/red wire) in the rear quarter panel and got a reading of 0 ohms with the taillight assembly disconnected.

I then connected the taillight assembly to the connector in the back and I checked the OHMs at the headlight switch connector (blue/red wire) with the jeep running and got a reading of 11.1 ohms. This should be 0 right?

Can I assume that I have a bad ground / short in the tail light housing?

cliffy

You are probably getting some resistance readings from the switch itself or the fixture/harness, trying to check resistance with everything connected typically causes weird readings especially because of the shared grounds. If it was shorted it would most likely be blowing fuses so from the info provided I don't think it is a short.

cliffy

I was re reading your initial post, you said that you have no power at the head light switch and that you replaced the visibly blown fuses I think you may have either a blown fuse or a bad light socket. I had my headlight switch break on me at work one night and it blew a fuse for the taillights I did not look at things too closely but discovered that some tail light features worked and some didn't and it was a 20a fuse but there is more than one that controls various lights.

tnovell

I rechecked all the fuses and everything is good. I noticed that the PO had unplugged some things and not plugged them back in (unless the cherokee came with unused wiring connectors under the dash.

I found a black 6 pin connector in the front passenger kick panel that isn't plugged into anything (i can't find a place to plug it in either). It does have a BLUE/RED wire going to it that registers 12V when the headlight switch is turned on. This leads me to believe that this unplugged connector could be creating an air gap in the RED/BLUE wire between the front dash and the rear lights. I am seriously considering jumping the RED/BLUE wire from this unused plug to the back tail lights as a fix. It turns on and off with the headlight switch.

After looking at a wiring diagram, I think this unused plug is connection C220 that feeds the overhead console.

I will run the wire tomorrow and keep you posted on my results. I'm anxious to get this jeep on the road.

PS. i finally passed emissions today. I installed a new catalytic convertor which brought my NOx readings down to 200ppm from 1300ppm before. $200 installed and only took 30 minutes. highly recommended to anyone failing the NOx emissions.

cliffy

Good luck, I am going to be curious as to the outcome.