Electrical gremlins: brake/indicator stopped working.

[TMG51]

Got my van stuck in a ditch yesterday. After pulling it out I noticed the driver's side rear brake light and indicator don't work (same bulb). Reverse light works. Changed the bulb, no effect. Checked fuses, all good. Traced the wire looking for obvious pinch points when it went in the ditch, found none.

Then I broke out the multimeter to test the wires. With the brake depressed, the wire to the bulb is hot, but it doesn't light! Now I'm confused. My only other thought is a ground wire got ripped off but I don't see any. Thoughts?

 

[SternWake]

Got my van stuck in a ditch yesterday. After pulling it out I noticed the driver's side rear brake light and indicator don't work (same bulb). Reverse light works. Changed the bulb, no effect. Checked fuses, all good. Traced the wire looking for obvious pinch points when it went in the ditch, found none.

Then I broke out the multimeter to test the wires. With the brake depressed, the wire to the bulb is hot, but it doesn't light! Now I'm confused. My only other thought is a ground wire got ripped off but I don't see any. Thoughts?

My dodge uses the cast metal reflector housing as the ground. If the bulb base is not touching the reflector, no workee, and all sorts of crazy crap starts happening to other signal lights that made me think my Van was possessed. 

Make sure reflector housing is grounded and bulb base can seat without any oxidation preventing current flow.

This does not really explain why it stopped working in the ditch, but could just be coincidence, and perhaps the bulb was not working for some time previous and only noticed because of ditching.

 

[anewbiewannabe]

I was going to guess the ground until I saw the last part. I always have trouble with the ground on my utility trailer even after running new wiring and making sure of the ground every time I go to use it one of the brake lights refuses to cooperate---doesn't matter what tow vehicle. Gremlins got be it.

 

[highdesertranger]

yeppers sounds like a bad ground to me. highdesertranger

 

[ramblingvanman]

Agreed. If you have power, and it doesn't work then either the bulb is bad or there is a bad ground.

 

[GotSmart]

I would change the bulb first.

 

[highdesertranger]

TMG did you get it figured out? what I want to know is the story behind getting stuck in the ditch. lol highdesertranger

 

[akrvbob]

It's very clear an exorcism is called for here.
Bob

 

[29chico]

I suggest that you run a temporary ground to the bulb in question.  If it lights up, then I would put a permanent add on ground lead to that bulb and move on.

 

[TMG51]

Okay, this was a weird one.

I verified continuity and then just for fun ran a temporary ground to the negative terminal. No effect. But I did figure out the problem. I had been confused because all readings on the bulb housing were correct but the bulb wasn't lighting....turns out the problem was the bulb housing itself. One of the brass contacts had cracked and gone out of place, no longer touching the bulb. As soon as I touched the contact it fell off in my hand (as pictured).

I gave 'er a temporary* fix with a bent piece of wire. Both brake light and indicator are working now.

*Temporary is defined as "I'll fix it right when it stops working again."

 

[highdesertranger]

glad you got it fixed or at least figured out. highdesertranger

 

[DomDagen]

Hey! I got the same problem on my Ford couple months ago. I change the multifunction switch and everything work great again! Sometime, you can just disconnect the switch, clean the terminals and put it back and call it a day!