tail light problem - fixed

[Johnzoku]

This is driving me up the wall… For some reason my MZ11’s left hand side brake light works fine and my Right hand side still works but is only 1/3 the brightness.

To add to this, when I have my tail lights on; when the brakes are on the left brake light still works fine but the right brake light doesn’t work at all.

Now so far ive checked that

-the connections aren’t corroded,
-all bulbs work fine,
-checked the main connection with my circuit tester; and out of the three for the brake lights (by my powers of deduction ) that one of those three work (the red wire with white line and blue track works - red wire with blue line and blue trace and white wire with black line and red trace do not work)
-ive also checked the wiring up to next to the boot popper and still the same result.
-And ive checked the fuses and they all work as well.

I looked at the TSRM troubleshooting on lighting and for the problem “only one light does not light (all exterior)” its possible cause is light bulb or socket, wire or ground faulty.

From here Im a bit stuck. Can anyone point me in the right direction? Should I try grounding the faulty wires at the connection in the boot? Or is there some other connections I should look at first, if so what are they and where?

[MWP]

Have you checked the ground wire connections to the chassis (make sure the bolts are done up, no corroded, wire hasnt snapped, etc)?
Itll be the connection to the chassis, or one of the grounding wires at fault.

[Johnzoku]

where would the tail light ground wires be, under the car to the chassis near the rear end, front end, comming off the brakes?

would it work if i jsut grounded the two non working wires near the main connection in the boot; to the boot some where?

[joecoolmk2]

the earth wire is usually bolted to the back of the boot near the lights somewhere.

[EldarO]

do yourself a favour.

for the light that isnt working, cut the active 12V.

then grab a length of wire and connect your working light to the one you've just cut.

that way, you'll have working tail lights, and the 5-0 will be happy.

Elmo.

[Johnzoku]

thats a good idea splitting the cables. ive figures out that the white wire with black line and red trace is the earth and that it doesnt work on any of the lights? followed it all the way up to the door and it doesnt work.

would the earth be bolted on to the pedal box area by anychance?

anyway, ill give eldar0's idea a go, seams like a good idea.

[LeeRoy]

I vote bad ground. Pull the light out and make a new ground (temporarily) and hook that up to a nice clean earthing point and see if it fixes your problem. I had a similar thing with headlights one being brighter than the other. Turns out the connection to ground was a bit corroded and it cause more voltage to go to the opposing headlight making one bright and one dim.

- LeeRoy

[joecoolmk2]

thats a good idea splitting the cables. ive figures out that the white wire with black line and red trace is the earth and that it doesnt work on any of the lights? followed it all the way up to the door and it doesnt work.

would the earth be bolted on to the pedal box area by anychance?

anyway, ill give eldar0's idea a go, seams like a good idea.

yeah, there's a switch behind the brake pedal, when you press your foot on the brake it completes the ciruit.

[Johnzoku]

ahh i thought as much... ill have to check that out. thanks.

i gave eldar0's idea a trial go, and it would work but i know its jsut the earth so i should be able to find it soon.

[BLACK77]

in some cars, not too familiar with this 1 but it is possible to put the brake/tail light bulbs in the wrong way. this can cause the situation u described. not callin u a noob, just bein helpful (had this prob on a vl....damn bombadores)

~mark

[Johnzoku]

well #1 ~ i am a noob to working on cars so no offence taken and #2 both bulbs are the same so i dont think thats causing it, 99% sure its the earth but thanks for the input

[EldarO]

most taillights wont let you put them around the wrong way, the two pins that hold the bulb in are at different heights on the side of the metal hat that the bulb is glued onto.

they only go in one way, you can sit them in the other way, but because the pins, and the slots for the pins, are at different heights, it wont slide in there, and stay there.

Elmo.

[Johnzoku]

ITS DONE!!!! im running the lights off the the working left one and put a new earth on the right. i tested from the brake pedal to the circuit board and tested from the lights to the board and i couldnt figure it out, everything works and theres a brake where i jsut cant get to it.

but its works now and thats what matters the most

thanks everyone for your help!!!!