My daughter, stationed @ Marine Corps Air Station, Cherry Point, NC. Sent me a text this morning. With the headlights "off" the driver side brake light does not work. When the headlights are "on" it works fine. I told her that there may be a problem with her light switch. Can anyone tell me what else might cause this?
I would suspect a bulb first, unless its an LED tail light. Then I would suspect a tail light connector problem. Some Jeeps have a circuit board in the tail light though. If its not something that can be tested with a test light or meter, I'm lost. But if one brake light works its not the brake light switch. The problem could be in the headlight switch but thats not the first place I would look.
IDJ is right .. bulb first.. but.. it could also be aBad ground connection in the tail light harness.... where the harness is grounded..or bad connection to the bulb inside the socket...this jeep probably a 3157 bulb...each filament has a wire sticking out at the both ends... but in the socket.. one end is grounded.. i have had to on a lot of cars.. use a probe and bend the contacts inward in the socket slightly so it contacts the wires on the side of the bulb base shown above..depending on the year.. it could be a lamp controller problem.. as a LOT of the newer models are multiplexed... think remote controlled..can you post a year??? so i might see if i can find a wiring diagram.. there are changes between some of the years..
it is a 2006 Patriot. But why would the light work with the lights on, and not when they are off? if it did not work at all, i would go straigt to the bulb, then check ground. the ground is the same for the bulb in both conditions.
Because the bulb shorts to ground when you step on the brakes... on the inside filament. Some are a pain to replace also...These new bulbs are not cheap either I can't tell you how many newer cars I see daily and I travel 60 miles each way to work..How many cars do you see with one DRL?..Just a little FYI if you ever have to replace a front head light Don't Touch The Bulb use the paper that comes with it to install it..The little bit of oil from your fingers is enough to burn the bulb out prematurly..It creates a hot spot where you fingers touch the bulb...Bob
Maybe Wayne will find the schematic.That is an odd condition, and I'm just betting on bulb because in my experience thats where 99% of lamp problems are found, in the bulb or socket. Sometimes they defy explanation. There can be a burnt filament laying on a good one inside the bulb or something wierd like that. If the trouble isn't the lamp or wiring, I suppose it could be the headlight switch or the turn signal switch for that matter. Hope its something light, no pun intended. Frustrating when lamps don't work right or have intermittent problems.
Aha! Bob and I were typing at the same time. Two votes for messed up filament in the bulb.
it its a patriot.. it must be a 2008 or newer model..i went looking in my free resources.. not listed...i did find a 2003 grand cherokee manual which should be the similar..and some 2005 JGC but the wiring diagrams for the brake and tail lights are weird.. i will need to probably print a dozen pages to figure out how it works.. i was hoping that they would have a look and swap the bulb and check the contacts before i try to comprehend the diagrams..
idrivejunk:Aha! Bob and I were typing at the same time. Two votes for messed up filament in the bulb.You know what they say?..Great minds think alike..LOL..Yeah I've had it happen to me.so it's a common problem,up North in the winter those bulbs burn very hot and with the cold air they blow out in a heart beat.. How you doing Bud? BobI'm still in the hospital, but hopefully today Monday (it's 1:30am). They are going in to find a bleeding artery after almost killing me with an over-dose of coumodin..The internest is certain thats what it is. So he's going to punch a hole in my Belly Button..Find the bleeder and cauterize the ends..I told him I want to be awake for the procedure..he laughed and shook his head..I'm not going to sleep for any-one they almost killed me so I'm not taking any chances..I hope to get out of this Bizzarro World and get back to reality..I need physical therapy so I will be here, probably until the weekend... Bob