passenger side tail lights - I'm stumped late update:fixed

[DrPizza]

2008 Dodge Grand Caravan, not that it probably matters.

No turn signal, no brake light, no tail lamp (on the passenger side.) BUT, the reverse light is just fine. Ahhh, it's a fuse! No it isn't. The fuse is fine. I replaced it anyway.

Ohhh, the bulb? Nope. Replaced it. Replaced it again. Put in a known working bulb, including the socket thing that the bulb plugs into, nothing. (And then the bulb continues to work when put back where it came from.

The bulb holder - 4 contacts that it comes in contact with. 2 are ground. 1 for brake, turn signal. 1 for tail lamps. Checked for a voltage with the lights on - Yep. Voltage is just fine. I even got some extra wire - connected it to the known ground & to the bulb. Connected a wire to the hot side of the bulb - and touched it to the terminal showing 14 volts. Nothing.

Wtf?! I was thinking, maybe there's a bad ground - I'd see the voltage, but there wouldn't be enough current. Great theory except that the backing light works - it's the same ground wire in the plug. Where the ground connects to the plastic housing, it runs in a thin strip of metal to both lights.

I'm stumped.

update😛roblem solved - horrible corrosion problem in the wiring harness.

 

[Bignate603]

Any possibility that the socket is screwed up in such a way that the light isn't touching the contacts? Or that the contacts have gotten dirty/corroded?

 

[DrPizza]

Any possibility that the socket is screwed up in such a way that the light isn't touching the contacts? Or that the contacts have gotten dirty/corroded?

I thought that too. that's why I connected a wire directly from the contacts to the bulb. And, I cleaned all the contacts with some electrical contact cleaner. I'll probably spend another hour working on it in the daylight tomorrow.

 

[foghorn67]

I do know that some older designs for turn signals need resistance to blink. But even so, the brake and running lights should still work. I'm stumped too.
If you want to chase the grounding theory, bypass that metallic strip and test it to the chassis.

 

[herm0016]

strange. try the flasher module?

 

[DrPizza]

I do know that some older designs for turn signals need resistance to blink. But even so, the brake and running lights should still work. I'm stumped too.
If you want to chase the grounding theory, bypass that metallic strip and test it to the chassis.

Yep, did that too. I'll have time tomorrow evening to work on it in the daylight (I hope.)

 

[nedfunnell]

strange. try the flasher module?

I'm not sure if a vehicle this new will have a flasher, but this sounds likely to me.

 

[DrPizza]

I'm not sure if a vehicle this new will have a flasher, but this sounds likely to me.

Would the flasher also affect the brake lights and tail lights (in addition to the turn signal?)

 

[LTC8K6]

It's a CAN bus vehicle. It's probably a bad module somewhere.

 

[BUTCH1]

Possible the BCM drives these bulbs, perhaps a voltage/current regulator circuit is failing under load, your DVM sees the 14V but the load draws it down flat. Try measuring the voltage across the bulb, (after you've used the wire hookup again) and see what gives. Also check the working side and measure volt's there for comparison..

 

[DrPizza]

I hate to bump a thread like this, but was searching for threads I created in here (for another reason) and thought that for anyone in the future, the solution here might help.

I pulled the whole assembly off and "unplugged" it. OMG, everything was completely rotted out. There was virtually nothing left to make contact. In fact, I had to either replace the whole tail light, else actually cut into the hard molded plastic inside to get to the metal, and solder on new contacts. I chose the latter; what a pita. Shortly afterward, the other side rotted out. My wife had either the dealer or a local garage put a trailer hitch on it; and they installed the wiring harness - which is apparently where all the corrosion started. The corrosion extended well inside the plastic for a couple inches.