Driver Side Brake Light Problem

[justin1987]

I was doing a system check on the car last night and when I was checking the rear lights, both turn signals worked, the lights worked when the headlights were turned on, and the passenger side brake light worked. The driver side brake light wouldn't work. However, it would work if I hit the brakes when the passenger side turn signal is going. I'm assuming it is some type of grounding issue. Thoughts?

[Dino]

Sounds like the contacts on the turn signal switch wore out.  Have someone step on the brake while holding the turn signal lever in the middle or wiggle it a bit.  If both brake lights work, the switch needs to be replaced.  Happened to mine as well.

[Roctania]

Grounds can and do go bad.  I just had to ground the lights on the 1971 Challenger to get them to work... new paint interfered with the ground path from both rear side markers. 

After checking your TS switch as per above, try this
Put the 4-ways on or block the brake lights ON. 
get your voltmeter handy.  Check volts at the brake light feed wire.  It should be ~12V anytime the lamp is on- always if you blocked the brakes on, flashing if using the 4-ways. 

If that is good, then check voltage from the bulb holder where it contacts the tail light housing to a Known Good Ground- perpaps a tail light panel mounting stud.  Both *should* be at ground potential, and so the voltage from one to the other should always be zero.  A faulty ground between these two points will show up as "some" voltage here.  More than 1V or so is a problem, since you only have 12-14 to begin with. 

It is possible for factory crimped blb holders to corrode and get crusty and painted and then fail to pass electricity. 

Here is my fix from this weekend, front park light, but the theory is the same:
http://www.dodgecharger.com/forum/index.php/topic,114765.0.html


The voltmeter will show where this voltage is failing to transfer to the next part in the circuit.