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Strange electrical problem-tail light

1K views 14 replies 5 participants last post by  three_jeeps 
#1 ·
My 2004 WJ drivers side stop/tail light has a strange behavior.

When the lights are on normally, the tail light illuminates OK (maybe be a little dimmer than the other tail light)

With the lights on, when I step on the brakes, the drivers side tail light goes off, and the drivers side brake light does not come on.

With the lights off, the drivers side brake light works normally.

Passenger side tail/stop light works fine.

With the drivers side tail light removed, and the lights turned on, if I smack the lens case, sometimes the light will go out. the brake light still does not work.

I haven't had time to diagnose this behavior, but I am thinking a bad ground or a broken wires.

Has anyone run into this problem before and what was the problem/solution?

Any pointers on how to quickly track this down?
Thanks
J
 
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#3 ·
I had some time to get into this. Absolutely no corrosion with connector pigtail and socket in bezel assembly. Busses in bezel assembly are continuous-no problem there. Light bulb and bulb socket are fine....

This is a VERY strange behavior. with the lights off, stepping on the brake pedal results in the stop/brake light illuminating. (as one would expect)

Now, turn on the lights (either parking or headlights), and both tail lights illuminate. (as one would expect)

Now step on brake pedal, and on the left (drivers side) tail bezel, the tail light goes out, and the stop/brake light does not go on!!

To eliminate the bezel assembly as a problem, , I removed it and checked the voltages on the plug with a volt meter - The voltages at the plug do show the same behavior as when the tail bezel is plugged in....the tail bezel assembly is not the problem....something up stream is acting funny.

I don't understand how stepping on the brake pedal with the lights off causes the brake light to turn on, but when the lights are on, stepping on the brake pedal results in a) no brake light, and b) turns off the tail light. The two circuits should be isolated......

Help pls!!! Any suggestions???? are appreciated!!!!
J
 
#9 ·
** Update - Fixed**

After checking the voltages at the tail light socket and verifying that they were the correct values at the correct time (e.g when I turned on the lights and/or pressed the brake pedal), I then swapped in the other tail light bezel...everything worked as it should. This told me that something was wrong with the bezel.

Even thought I checked the continuity of the buses in the non-working bezel, and even bent the contacts on the light bulb holders (plugs), it still was not working.
After some head scratching I noticed that the contacts on the inside of the bezel where the bulb 'plug' goes, could be bent up....they were pushed into the plastic too far that when the bulb plug was inserted and rotated, the contacts on the plug did not touch the mating contact in the bezel....bending them up a little solved the problem.
thanks for all the suggestions...
 
#11 ·
The bulb was in 180 degrees off..... Had the same issue, right after I put a new bulb in. Was bored waiting for a train to cross outside of town one night after work and pulled the bulb(3157) saw both filiments were intact, flipped the bulb 180 degrees and put it back in.... Problem solved, for me anyway.
 
#12 ·
No, the bulb in my tail light was not 180 degrees off. I am not sure this can happen as there are two keys on the 'plug' and the widths of the keys are different enough that one can't put the light bulb clip in the bezel without breaking something.

The root problem was that the contacts on the bezel were pushed down so far that they did not make contact with the finger contacts on the plug, no matter how much I bent up the finger contacts on the plug.
I am guessing that over time, the contacts in the bezel will relax enough and drop down, and the problem will reoccur. To prevent this, I think I'll insert a small plastic or wood 'shim' between the plastic and the contact and secure it with a dab of hot glue or epoxy. That way the contact will not drop down.

Any yes, one must make sure that for the tail/stop light, that the light bulb is dual filament.

IIRC, the bulb and the bulb socket (e.g. plug) are designed such that the lights will work no matter what direction the bulb is inserted into the socket. I suspect what you experiences was that the base of the bulb was not making good connection with the copper contacts in the plug.
 
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