weird electrical problem on bake lights 92 corolla 1.6

[lemegacool]

so my gf's car has this little problem that have me stumped... i dont know where to start looking

i'll put it in pics for you guys (the car was not running for the test)

this is when i press the brake with the headlights off (car not running) notice left light is half lit





this is the position lights (headlights on car not running)
they are normal





and this is when you press the brake with the headlights on (car not running) left light completely goes out!



sounds like a short... but WHERE?!? i suck at car electrical diagnosis lol
thanks for any help!!!

[SuLLiVaN88]

did you check the bulbs to make sure none are burnt out

[barthmonster]

just helped a buddy with brakelight issues on a Camry. It was the 'yellow box' in the trunk which is a 'lamp failure detector'. If you can find one like that under the carpet near where the gascap is (I'm not sure if the Corolla has this or not), then take it apart and look for burned circuit-board and fix...

[SuperRA]

I've had this problem on my corolla before. It is the bulb holder inside that gets hot and melts away from the mounting base. This in turn un-grounds the bulb and so when you step on the brake, the circuit trys to go through both filaments (park, and brake) and then grounds through the park light circuit somewhere. So because it's going through two filaments, it has more resistance thus lower current thus the low illumination. When the headlights are on, that ground it was finding is now gone because you are powering the park light side, so when you step on the brakes, you are supplying 12v to both filaments which have no ground, thus no voltage potential across the bulb and thus no light.

It may sound a bit confusing, but I'm pretty sure if you take apart your taillight, and look at the ground connections, you'll see that the grounds are loose and probably not contacting. What I did was go and solder a wire to the bulb holder guaranteeing a ground and have never had a problem since.

[lemegacool]

Originally Posted by SuperRA

I've had this problem on my corolla before. It is the bulb holder inside that gets hot and melts away from the mounting base. This in turn un-grounds the bulb and so when you step on the brake, the circuit trys to go through both filaments (park, and brake) and then grounds through the park light circuit somewhere. So because it's going through two filaments, it has more resistance thus lower current thus the low illumination. When the headlights are on, that ground it was finding is now gone because you are powering the park light side, so when you step on the brakes, you are supplying 12v to both filaments which have no ground, thus no voltage potential across the bulb and thus no light.

It may sound a bit confusing, but I'm pretty sure if you take apart your taillight, and look at the ground connections, you'll see that the grounds are loose and probably not contacting. What I did was go and solder a wire to the bulb holder guaranteeing a ground and have never had a problem since.

thanks its all clear i understand!

as soon as i get acces to her car i'm going to look at bulb grounds... thanks!!! will probably hadwire them too

[SuperRA]

Originally Posted by lemegacool

thanks its all clear i understand!

as soon as i get acces to her car i'm going to look at bulb grounds... thanks!!! will probably hadwire them too

Cool.

Let us know if that indeed was it. I do see a lot of corollas that have this problem on the road. With these old cars you never know what can go wrong.

[lemegacool]

Originally Posted by SuperRA

Cool.

Let us know if that indeed was it. I do see a lot of corollas that have this problem on the road. With these old cars you never know what can go wrong.

that was totally it! i just tightened 2 ground screws and VOILA! back to normal! i'm going to drown these sucker in solder now

HUUUUGE thanks!!! god i love this forum!!!!

[SuperRA]

Congrats! Lol.

Thanks for using VIOLA and not WALLAH. HAHAHA.