Odd electrical issue

[FrenchPople]

Hey guys, long time no post.

Last year I got myself a 1993 Nissan Pathfinder SE Sport(yes I love the capability). Well I recently ran into an odd electrical issue. When I turn the ignition to the on position and dont turn anything on the right rear tail light(not the brake light) turns on. If I turn the right turn signal on the left tail light(again not the brake light) will flash with the right turn signal. If I turn the marker lights on I dont really see the issue(but don't necessarily want to run the lights all the time).

What have I done for checks? Well I disconnected the headlight switch and turned the ignition on. No change. Disconnected Joint connector B(under the dash next to the steering column). No change. Disconnected the right tail light housing. Now the left tail light comes on with ignition on but does not flash with right turn.

So far with all this I have determined that my issue is somewhere in a harness cross shorting. My question is has anyone on here seen anything of the sorts? If so what did you find and what else would you recommend I check?

I will add that I have the Factory Service Manual on hand.

Any help is appreciated

[VStar650CL]

Sounds like crossed filaments in one of the bulbs. Try new ones before anything else.

[mdmellott]

Sounds like crossed filaments in one of the bulbs. Try new ones before anything else.

Brake light filament deformation. That's Dr. House-like diagnostics.

[VStar650CL]

Brake light filament deformation. That's Dr. House-like diagnostics.

"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."
-- Sherlock Holmes

I've seen way too many perfectly good mechanics pull out way too much hair over weird problems from crossed bulbs (or from Harry Backyard installing the wrong bulbs). Gotta exclude the obvious first.

[FrenchPople]

I appreciate the responses but I'm having a hard time understanding. This is the first I have heard of Brake Light filament deformation.

Also the brake and tail lights have a switch power with a constant ground. Its the same with the turn signal bulbs.

Please explain a little bit more on that

[VStar650CL]

If the filaments in a bulb get cross-circuited, both circuits will respond to one another when either one is activated. Depending on whether the crossed filament is broken or still intact and whether the driver circuit is open like the turn signals or grounded through other bulbs like the running lamps, all kinds of bizarre and seemingly inexplicable behavior can result. Bulbs are cheap and easy, eliminate them first.

[FrenchPople]

Ok now a little more sense is being made not entirely. How so? Well as mentioned in my last post the turn signal bulbs are different then the tail and brake light bulbs on this. Looking at the wiring diagram the only thing I could see that they would remotely share is the ground at best. The right side tail and turn(from the rear assembly) do share a ground. The left assembly for turn and tail have a separate ground. With all that said it seems more then just a bulb

[VStar650CL]

See if maybe the ground connection to one or both taillight assemblies is open (disconnected). The bulbs back there usually all share a ground wire on each side. If that's open-circuit, then the lights on that side will find a ground wherever they can, which will be back through a different filament in a circuit that still has ground, such as the opposite taillight.

[FrenchPople]

And that bit makes sense. What still doesn't make sense is where is the tail light getting power from with just the key in the on position and the light switches(turn included) off? All I have to do is turn the key on and it will turn on. It makes me the there is a very small short to power for the tail light circuit but I'm not too sure where it would be. I'm also suspecting in the same area is where the turn signal might be causing issues with the tail light.

[VStar650CL]

Something has to be crossed-up. If I recall, the only things back there that will have switched ignition power are the evap Vent Valve circuit (that's powered by the ECM/ECCS Relay) and the Fuel Pump circuit (that should have it's own relay). We saw that once on a Sentra with rodent-damaged wiring in the Body Harness, although it was the engine sensors being affected and not the taillights. You might want to first track down what circuit the juice is coming from by pulling fuses. Then you'll at least know what tree to bark up.

[FrenchPople]

Alrighty then!! I have fixed said issue!! So for those wondering I suggest not installing the LED lights in the brake light assemblies. To start when I did replace the bulbs I did get led. Why you ask? Well the left side was cracked and letting water in(not a good thing when OffRoad) and caused the bulb to burn out quick. Due to that i finally replased both tail light assemblies tonight. I keep the regular incandescent bulbs in to see what would happen. Lo and behold the problem went away!! For what its worth I'm happy with said results.