Question about 2000 Jeep Grand Cherokee
When the headlights are not on - all brake lights function properly.. as soon as I turn on the headlights the Left brake light does not work. Have taken it to a jeep dealer and another shop and one told me they could find nothing wrong -- the dealership told me they fixed it but they didn't. Tried changing the fuse and it doesn't help.
If you take the tail light assembly off and take the bulb out, you'll see three metal contacts on the tail light assembly. Pry them up slightly and slide a small, folded piece of aluminum foil underneath it.
Replace the bulb and try to reproduce the problem. I found this fix online and did it to both sides of my car.. no problems since
Posted on Sep 23, 2008
I own a 2000 Jeep Grand Cherokee and I too had the same problem on the left tail light/brake light. Thanks to this website, I've regained my sanity (and stopped changing light bulbs). Additionally, I was not going to pay for a part unless I absolutely had to, and I was able to repair the light with info from this website. In return, I thought I'd post how I did it.
1. Remove the tail light assembly. Most of you know how to remove the light assembly if you've changed bulbs, so I won't cover that.
2. disconnect the wiring harness by sliding the red locking clip to the side in order to press the side of the male connector and pull apart.
3. Once you've got the tail assembly away from the vehicle and on a bench, remove the light socket for the tail/brake light. You will see 3 silver contact points inside the black plastic ring. 2 are grouped together and there is one that is opposite of the 2. The one by itself is the ground; the other two are the contacts for the tail light and brake light. The problem lies with the ground connector. (BTW, I tested continuity with all lights and contacts including the turn signal and the reverse light to verify that the circuit board itself was good, and it was).
4. clean all contacts with a Q-Tip and some sort of contact cleaner - rubbing alcohol will work.
5. You should notice that the ground contact is depressed into the plastic and the plastic itself is slightly warped down. I was able to use a small pair of needle nose pliers that have a 45 degree angle to press up on the contact from underneath using the opposite lip of the hole as leverage (very carefully). Once it had moved up a bit, I was able to wedge a mini-flathead screwdriver in between the metal contact and the plastic to force the contact up even further (again, very carefully). Once it looked even with the rest, gently reinsert the connector and test.
Hope this helps...
Posted on Sep 24, 2008
scan the PCM yet?, for DTC errors.
is the battery at full 12.6vdc rested,?
does engine run ok?,
car drive ok?
do the headlights have full brightness.? brakes off and key in pocket?
never take a working car to any shop they cant fix working cars. (can't fix working cars...)
(but they will take your cash. no lie)
so what does this mean, ?
(im not going to guess like others.. ok)
Left brake light "does not work"??? (huh)
not work, (dead or dim?)
so the other brake lamps glows. with brakes and HL on. ok?
but the left does what. exactly,
ever take of the lens and watch all elements to see what is happening? with actual elements?
do brakes or HL or parks on cause fuses to blow?
does the park lamp on, cause the brake element to glow?
is that it?// yes, then park is shorted to brakes.
but that short causes both brake elements to fail, this way....
or is the brake element dead (out), with parks on? and brakes depressed.?
i have the full schematics, need that? sure...
it's not like a 1993 at all. sorry.
first is rule 1, if car has brass base lamps, they do short. (even in 1957 they did)
so replace all3 brake lamps. (this gets parks too)
the HL on , is park, did you see if the brake lamp fails just on park selected? and not full on head lights, sure, it did....
it's really park lamps doing this, and are all park lamps glowing front ,rear and side of car? in PARK? see my answers are mostly questions, as im blind and cant do the tests carefully my self....see?
there are many park lamps on the left side,
did you look at all of them? even front parks and side marker parks?
the Design, 101:
the newer jeeps run a BCM to control relays for lamps."body control module (computer it is)
lets review this design
the park switch(1 or 2clicks) closes at hand
the BCM sees this pure digital signal and the BCM commands on the park relay ,it closes and sends park voltage to all park lamps. (all are in parallel (key fact 2)
the head lights do not go to the rear of car, and is not related. (only park feed) not arguing just making the path clear. park.
it's park. (aka, as tails wrongly many times.)
"now the tricky part the relay oddly grounds the park feed, when not in park or HL mode."
HL means head light.... jargon...
the brake switch is not BCM operated at all, (clue3)
it has JUST a brake switch hardwired to the brake rear elements. (x3)
and the 3rd center lamp, does it fail too? not stated.
all 3 are in parallel so if there is a short, all 3 fail as one. does it ? seems not....
did you do the tests in the dark? to see other symptoms,? dim glowing ,etc?
dead or stuck on. both. or one is dim.
if the lamp is bad, (inside) they can short anything in there. (ground ,brake and park is there)
that is why replacing the silly lamp is job 1.
if the park shorts to HL
and hl are off, the brake element is now grounded from the relay.(ground)
this is what is happening in your car.
the lamp is shorted. (my guess, but i use my meter to not guess)
why not replace the $1 bulb,
and not get china bulbs that love to short, (cheap junky bonding glue inside base shell)
the secret here is the park line is grounded on this car, in park off. (HL and parks off)
unlike most other cars made. (yes tricky)
see my drawing to prove that.
this is your jeep (usa spec)
the park feed is grounded in park off. (HL and PARK OFF) !
also look for tailer wiring hacks first. then prev. collision damage to all brake wires. on the rear. careful inspections, find most of this fast. inspect each of the 3, brake blub sockets for damage of any kind and for sure SHORTS, after 3 new lamps replaced. (L/R / and center)
did i nail this subject, good !
this is the park relay. and is shown OFF.
now lets do the fails other guessed here wrong.
the problem with helpers doing anecdotal stories, is that this is your car, not theirs! and your failure. (there are many fail modes so.... lets do just your car, not mine, not others... and silly guessing.)
1: the park socket pin open (retracted or rusty)
only kills that park element, sorry! that is a fact. this will not effect brakes ever. (lamps good) same is true with retracted (or rusty)brake element, only that one brake element) fails.
if the lamp ground fails all lamps fail that socket.
if main ground g200 fails, all lamps on rear of car fail dead.
2: the park wire is grounded when off.(at relay)
so knowing that, you then you know if the brake wire is shorted to park left. (by any means)
the brake fuse blows. (a dead short, it must)
(electric facts) that is because all brake wires are in parallel, and if one shorts all brakes are shorted.
but if ground is rusty there. (omg a double failure) the fuse might not blow. and you get dim lamps. brakes only, HL and park is off. now.
3: if the park wire is shorted on the left side to ground(by any means) that means the park fuse blows. as you flip the HL lever 1 or 2 clicks on.
if park is crossed over to brakes, all elements glow, all park and all brake.
brake and park, with park switch on only,
that is a bunch of lamps.
3 brake at rear.
2 rear parks
4 sides of car park
2 front park.
11 elements glowing or fuse blows.?
if the brakes are turned on now,with same crossover, and not park ON.
then the brakes see a ground (park relay) and blow the brake fuse fast. G200 ground good. (assumed)
end factorial.... i can do more, and double fails.
i was thinking last night why does jeep ground the park feed, when not used. (at relay)
this prevents park/brake crossvovers, from causing
all 11 elements to glow (parks on , brakes depressed)
(omg front/side parks too , brakes on.)
they want the brakes lamps to only glow, brakes on
never the vast parking lamp feed, going hot. wrongly. and to blow the fuse, telling you that there is a huge short in the brake feed.
that is my idea there. Kinda cool really.
this cars interior lamps all have BCM drivers
so is not effected. (isolated it is)
some GC cars, have aiming head lights and a motor.
and this motor is wired to PARK feed. one more fact. i cant comment on that .. dont have it...here. (not fun to diagnose that..)
and the park feed goes to that, and to all park lamps front rear and side.
if the park main feed fails, all parks die.
if the park feed grounds, all fail. they are in fact run off ONE park feed.
The same is true on brakes, they are all parallel
but is not connected to park at all, in any why.
i have the book to prove all that.
only double fails are tricky.
i found this in google
the full park path.
Posted on Jul 02, 2015
Check bulb in rear ive seen carbon build up cause problems aslo check bulbs for crossed filliments just replace them all there cheap enough
Posted on Sep 20, 2008
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