Need help with a brake light problem/short

[anthonyc]

Whats up guys, heres my problem98 qx4

when headlights are off, both tail lights work as they shouldwhen headlights are on, the passenger tail light turns off (goes black )when i hit the brakes.its on when im off the brakes though

ive replaced all the bulbs in the back, and 2 bulbs i had up front that were out.

what do i do next?

[fueler]

IF its really not the bulb (check again) then its probably a grounding problem. Either an insufficient ground to the assy or a positive to ground problem. As you mention only a problem with the passenger rear, I would check for a poor ground related to that light assy or possibly one of the bulbs' internal filaments in that assy touching each other. Or possibly a socket failure at that assy.

Good Luck

[bmlawless]

Whats up guys, heres my problem98 qx4

when headlights are off, both tail lights work as they shouldwhen headlights are on, the passenger tail light turns off (goes black )when i hit the brakes.its on when im off the brakes though

ive replaced all the bulbs in the back, and 2 bulbs i had up front that were out.

what do i do next?

Just to make sure we are on the same page, let's clarify some terms. TAIL LIGHT = The low-intensity (dim) lamp that is only on when the headlights are turned on.BRAKE LIGHT = The high-intensity (bright) lamp that comes on any time the brake pedal is pressed.

If I understand you correctly, you are saying that your brake lights work fine unless your headlights are on. Then you are saying that stepping on the brake pedal while the headlights (and tail lights) are on causes the right brake/tail light to turn off completely. Then the system goes back to normal when you let off the pedal.

If this is correct, then it sounds like there is a problem grounding right rear brake/tail light socket.

When the ground for the circuit is working, both circuits will be able to run current through the bulb and to a common ground. When there is no ground, the current will try and find another path to take. When the tail lights are off, current flowing to the brake lights can use the inactive tail light loop as a ground. When the lights are on and the brakes are off, the current through the tail lights uses the inactive brake light circuit to ground. When both systems are activated, there is no where for any current to go so neither circuit works.

[anthonyc]

you guys are a tremendous help, thanks. will see if i can get this resolved soon.

[anthonyc]

resolved, i hope.

i hit all the bulb sockets in the back with wd40. still wasnt working. then i took out the driver side tailight/brakelight bulb, then hit the brake with the headlights on, nothing. then the brake light came on after a few seconds. put the other bulb back in, and both are working now. i dunno.

[bmlawless]

Definitely sounds like a bad ground. I'll bet that if you tapped on the light while the brake lights were on you would see it go on/off. When you put bulbs in, always use dielectric grease. It will help with the connection, prevent corrosion, and make it easier to remove the bulb years later.

[slickroger]

If it isnt what bmlawless said than the two fillaments in the bulb may have been touching simply because its a combination bulb and thats why tapping may have helped.

I had the same problem and it was just the bulb was touching because i bought a replacement, it worked. than i looked at the other tapped because they were touching and they both worked.