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Tail Lights Come On When Doors Open

dustybill

NAXJA Forum User
Location
Arizona
When I open the front or rear passenger door, the right tail lights and both back-up lights come on, and the interior lights slowly dim.

When the right turn signal is on and I step on the brake, the flashing speed increases and the brake and tail lights blink.

I have found that current is coming back through the ground circuit. The bolts holding the rear grounds on the left side of the cargo compartment are tight.

Does anyone have suggestions on how to go about finding where the problem is? I have the FSM, test light and meter.
 
That’s pretty cool. I have a Ford Escort that does something like that. When you hit the brakes, all the exterior running lights come on. If you hit the brakes with the ignition off, the interior lights and heater fan comes on.

But it’s a Ford and I don’t care.
 
scottmcneal said:
Clean all your grounds, start at your battery.. then your block an fire wall, all of them clean then real good
I dont know what your problem might be but this guy scottmcneal is on drugs.
 
Got a short somewhere, the harness for the front and rear dome light switches runs down the side, maybe something gnawed through the wires somewhere. I'd start at one end or the other and check back. Maybe start at the tail lights and work towards the fuse panel and see if you can isolate the problem. Or start at the fuse panel area and look for problems there. Either way take a look at the FSM wiring diagrams first.
 
My 89 did the same thing, the ground on the firewall was broke, so i fix it an now every thing works right. i don't know why, but it does.
 
ColoradoJeepXJ said:
When you hit the brakes, all the exterior running lights come on. If you hit the brakes with the ignition off, the interior lights and heater fan comes on.
.
That's friggin' awesome on SO many levels :laugh2:
 
Jeepsloth said:
Got a short somewhere, the harness for the front and rear dome light switches runs down the side, maybe something gnawed through the wires somewhere. I'd start at one end or the other and check back. Maybe start at the tail lights and work towards the fuse panel and see if you can isolate the problem. Or start at the fuse panel area and look for problems there. Either way take a look at the FSM wiring diagrams first.

We call those "Short Gremlins", they are second cousins to "Knawing Gremilns". They love a good light show! :sunshine: LOL.

Also might check for a "Short Gremlin" Infestation at or near the ignition switch.

I agree with the suggestions to rework and clean all the ground wires under the hood.

So what Year Jeep is it?
 
It's a 1998.

The braided cable from the firewall to the cylinder head is tight. I did not take it loose and clean it, as it looks good. The small ground from the battery to the fender was taken apart and cleaned 3 weeks ago.

Progress to date:

Took off the right rear trim panel in the cargo compartment. Checked the connector, found 12 volts on the ground wire. Disconnected the connector and left it disconnected for 5-10 minutes. The voltage at the ground wire dropped to about 0.5 volts! Why? I buttoned every thing up. Everything worked fine for awhile, then the problem re-emerged.

The ground wire runs to a splice, with several other ground wires going to it. Current could be coming from any of them.

I also have an intermittent operation on the passenger window switch. I have not looked at the schematic, but this may be where the short is.

dustybill
 
yep, drugs, sorry it didn't work for you.. but you are getting FEED back on your ground ...like i said mine is a 89 so i'll go out an look at it to see if any thing pops up..trailer wiring does look good if you have one..it cause my cruise to turn off when i hit my left blinker..
 
scottmcneal said:
go to school an learn, grounds makes things act funny.. ask some old electricians that work on old home, feed back sucks...

I've got a big sign on my wall in my office that's been there for probably 30 years.

If it's not grounded, it's not DEAD.

You can never have to much ground, all the grounds you looked at that you thought looked good. Check them, you can never go by looks alone.
 
I FIXED IT!!!!

I was going to check the grounds behind the spare tire, but decided to see if the harness runs under the seat from the right side to the left. It does! I first looked at the left side, checking for broken wires etc. I then walked over to the right side. Tracing the harnes from the rear to the from I found where the harness makes a left turn to go to the left side of the truck.

Well what do you know!!! There were two black wires running from the harness to the floor pan lip. They were connected to a ring terminal. The bolt holding them was loose!!! I could wiggle the wires around, and make the interior lights go dim or bright. I tightened up the ground and now its FIXED!!!!

The FSM does not show this ground. That lead me astray. Had I known about this ground, I would have fixed this weeks ago.

Thanks to all you folks who kept insisting that it was a ground. I checked the firewall and other grounds, which were ok. I did not really believe that it was a loose ground wire. I was thinking that it was an uninsulated power wire that was touching the chassis.

Sometimes a little manual harness tracing is worth hours of schematic studying.

dustybill
 
Glad to hear, i didn't know about that ground.. i'll go an check mine today when i get a chance.... thanks for letting us know you got it done..
 
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