Mysterious problem with left brake light
 

Hi

My Chrysler Neon's left brake light is not working when driving lights are on. Tail light is working correctly but also dims out when brake pedal is pressed. If lights are not on, brake light works properly.

I measured the voltages from the left side socket:
1. Lights on (~8 V). Everything working correctly.
2. Lights out, brake pedal pressed (~13V). Same function as right side which works properly all the time.
3. Lights on, brake pedal pressed (~0.5V). Obviously there is a short circuit, but how in the earth it is possible. In my understanding there are three wires coming to the socket and all are working correctly when operated separately but not together?

Alright, if somebody has any clue what might be the problem please let me know.

Thanks, Joonas

1thing to try is to replace the stop and tail light bulb.
If a filament in side the bulb has dropped funny it can cause similar problem.
Let me know how you get on.

Do you have the wrong bulb in it? Are the filaments touching inside the bulb? Corrosion in the socket?

Bad ground. Can pass current for one filament but cannot pass current for both. Find the ground wire for that side, loosen and re-tighten the screw.

I think the problem could be with bad wiring to the socket. I can't seem to find any info of the tail light socket and I don't see any screws there. Black wire should be the ground, right?

How can I remove the socket or the wire and reconnect it or should I buy a new socket altogether?

Black wire is the ground. Follow it to the ground point. Shouldn't be too far.
If that doesn't work, get a whole new socket. Try a parts store. If they don't carry it, go to the dealer. You won't break the bank.

Got it partly figured out. As you said the problem was bad ground and I tested it with a extra wire going from the bulb to ground. I'm going to put some crc to the socket and if that doesn't work, I'll buy a new socket.

Thanks a lot for your help!

Joonas.

If the problem is a bad ground, then replacing the socket won't fix it. You've got to either run a new wire to the socket from a new ground or trace the harness to the old ground and clean the connection there.