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Tail Lights don't work, blinkers/brakes do???

37K views 27 replies 13 participants last post by  Bendel 
#1 ·
Hello,

So, I've been cringing whenever I drive these days because on my 2008 Jeep Commander as I'm driving along my tail lights on the driver's side are black. But when I use my directional or hit my brakes the appropriate bulbs light up.
I've asked my mechanic but he said it's a wiring thing and he's not comfortable hunting for the problem. (Needless to say, I'm now on the lookout for a new mechanic...)
It seems like something I should be able to fix, though.
Someone suggested it could be a grounding issue so I removed the screw attached to a white wire connected to the frame of the vehicle. It was pretty corroded so I was kind of excited as I sanded, thinking I've done it!
But nothing.

Just wondering if anyone out there might be able to help me figure this bad boy out... The frustration level is high and the money level is low so I hate to take it to somebody and have it be something simple and never know for sure.
Any help would be much appreciated!!!

Thanks...

Shane
 
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#25 ·
@jason55330

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#3 ·
The running lights are a seperate filliment/circuit in the tail lights - the brake and turn signals are a different circuit. My first try would be to change the problem bulb which has two lights in it (one for brake one for running). If that didn't fix it I'd look for a connector problem with the wire that goes to that bulb or the bulb socket. The wire on both sides for the running lights will be the same color, the brake/turn signals will have different colors in left and right side. Idealy you should put a volt meter on the bulb socket and check for 12V. Since the other side running lights work there is not a fuse problem (probably).
I had an Olds back in the 70's that had a fuse blow in the tail light circuit and it caused the interior lights to stay on all the time - had to disconnect the battery until I figured out the cause. Found it by checking ALL the fuses.
 
#5 ·
Dont know if you guys checked this fuse out. If not, definitely fixed some issues for me... Its a blue 15. Found the info and location in my drivers manual.

I had a few issues going on. My dashboard was displaying "service 4wd", the BAS light and traction control symbol were intermittently coming on as well as discovering that I had no brake lights at all... I went through a lot. Had it down at the dealer a few times, they flashed the computer, all kinds of crap... I ended up taking it upon myself to replace this fuse that is related to the brake light system and... POOF! All issues fixed! For PENNIES!

good luck.

 
#7 ·
Fixed It!

Thanks for all the ideas...

I shouldn't have been so quick to discard the idea that it might have been a fuse. That's exactly what it was!
In the fuse box closest to the front of the vehicle, there is a row of 3 red, 10 amp fuses. The fuse closest to the windshield was, indeed, blown.

Even better, there were two spares enclosed in a yellow plastic wrapping right in front of the problem fuse row.

Mechanics couldn't figure it out which led me to believe that it couldn't have been something simple. "A wiring issue", they said.

Fuse.
Fixed.
Free.

Gotta love it.
Thanks again, for the brainstorming!
:thanks:
 
#15 ·
...Even better, there were two spares enclosed in a yellow plastic wrapping right in front of the problem fuse row.....
This may vary over the years for Commanders. But for my 2010 the cover for the fuse box labeled these fuses "Spares" but they are NOT, the O.M. and Quick Start Guide diagram shows these as the Ignition Off Draw (IOD) Fuses.


The IOD fuses power several things, including the Radio and Air Bags. Perhaps these fuses are different in your year commander.


When I pulled these fuses and used them as spares for another blown fuse. It fixed the original problem, but created new problems in that I had Air Bag Lights and the radio wouldn't work. I replaced the fuses I pulled, thinking they were spares, and it fixed everything.
 
#9 ·
Not so lucky for me.

I've checked every fuse I could think of and I am still not having any luck. I just bought the Commander a couple weeks ago so I called the dealership I bought it from and they are going to take a look at it today since it is still under their 30 day warranty.
 
#10 ·
Have someone run some codes on the computer and see if any come up. I think some autozones do it for free... I ended up getting a code that stated something like "Brake switch half stuck". Prior to replacing my fuses, I went to the dealership and got the brake switch and installed it my self. It was like $14 and pretty easy to install (right behind the actual brake peddle)...

Anyways, in my case it was in fact the fuse but in your case could be the brake switch... Who knows. The brake switch does control the lights though...

Here is a cool trick if you were not already aware for trying to pull codes yourself... Give it a shot, but if you dont get any codes, it doesnt mean that there are not some that a diagnostic machine couldnt pick up. So do that too if need be...

http://www.youtube.com/watch?v=0KLX9qi0llI
 
#14 · (Edited)
Thanks for all your help. The dealership was able to find the problem. It was with the U-Haul trailer light harness deal that was spliced in to the cables.
Specifically, it's actually the signal converter that can go bad.

I had the same problem not that long ago but in my case, it was the running lights that were not working; the signals and brake lights worked fine.

All three functions of the tail lamps - Brake lights, turn signals and running lights all run through the signal converter on their own individual wire - Brown, Geen & Yellow I believe are the colors, but I don't remember which is which off the top of my head.

If any one of those wires running into the signal converter goes bad, you will lose that particular function of the tail lamp. The upside is the signal converters only cost about $45.00 and they are not hard to wire back in as long as you pay attention.

You can also lose a function of the tail lamp if you have a ground (or short) on a particular wire somewhere, which would cause you to lose one function of the tail lamp, IE Brake lights - but still have turn signals & running lights working. The only way to isolate the problem is to trace each individual wire one by one and make sure there are not any frays, breaks or cracks in the wire coating anywhere where an exposed (bare) wire could be grounding/shorting out against another piece of metal from the vehicle's chassis, trailer frame or what have you.
 
#12 ·
Cool. Glad you got it fixed. Must be a relief for you... Figuring that one out yourself probably would have been pretty tough so I guess it panned out pretty good. Although I have heard of that trailer hitch wiring deal causing the same sort of issues. Who would have guessed though. Anything aftermarket with these jeeps seems to have side affects in regard to the electronics. I had a buddy that had an aftermarket car starter installed in his commander and it caused all kinds of issues for him... Just something to think about.
 
#20 ·
Hello,

So, I've been cringing whenever I drive these days because on my 2008 Jeep Commander as I'm driving along my tail lights on the driver's side are black. But when I use my directional or hit my brakes the appropriate bulbs light up.
I've asked my mechanic but he said it's a wiring thing and he's not comfortable hunting for the problem. (Needless to say, I'm now on the lookout for a new mechanic...)
It seems like something I should be able to fix, though.
Someone suggested it could be a grounding issue so I removed the screw attached to a white wire connected to the frame of the vehicle. It was pretty corroded so I was kind of excited as I sanded, thinking I've done it!
But nothing.

Just wondering if anyone out there might be able to help me figure this bad boy out... The frustration level is high and the money level is low so I hate to take it to somebody and have it be something simple and never know for sure.
Any help would be much appreciated!!!

Thanks...

Shane
Same problem here 2007 3.7
 
#23 ·
@Shamorryl

Welcome to the forum;

Please read the 1st post of the New Member Required Reading below & complete your user profile signature as directed;


This is a forum requirement for membership.

Thank you.
 
#26 ·
@Bendel
I added your signature with the information you provided, I know if using a smart phone it is very difficult.

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