Left turn signal/brake light intermittently works????

[draggin95niss]

On my 98 ive developed an issue thats got me stumped...the left turn/brake light is randomly not working, ive probed at the plug and its getting signal to the socket, ive checked the grounds etc also moved the harness around to replicate the problem with no avail, also with the key off i hit the brakes and all works but if i flip the trun signal switch either way the corresponding light turns off, this doesnt seem right...i just wanted some others input before i go throwin parts at it...

 

[LoneCynic]

I've got almost the exact same problem happening with my 1991. I replaced the tail light housings and put in all new bulbs. The passenger side works without fail, but the driver side only comes on when I turn the parking lights on. Pressing the brake pedal in or flipping the left turn signal on results in nothing. The bulbs obviously work, because it lights up when I put the parking lights on, but won't light up for any of the other functions. This has me stumped as well at the moment. Any tips to try would be appreciated by me as well.

 

[GMRedline]

I had a similar lingering issue on my Suburban for months but with the passenger side. It worked, it didn't work, it worked while braking sometimes, it worked while turning, it worked with a trailer hooked up, and now it doesn't work at all.

I've been through the connections at the rear harness and the trailer harness. And cleaned the rear ground.

Please have mentioned to check the connections and bulbs in the front because they can effect the operation of the rear.

I'm leaning toward the multi function switch but I haven't made the time to replace. And they are $$$ brand new.

 

[GMRedline]

Turns out it was my trailer harness. I didn't expect something so simple to fail...

 

[draggin95niss]

The p/o had put in a trailor t harness and uve removed that but no luck yet, i never really know when its gonna work or not...ive shook the harness and went over everything underneath...

 

[draggin95niss]

So ive dug a lil deeper this morning...it was acting up this morning so when i pulled the drivers light it started working correctly and then acted up again when i attempted to put it back in so i slowly pulled it back out and easily moving them around at the plug and was able to make it act up and work correctly so im guessing my problem lies in the plug...

 

[LoneCynic]

Turns out mine was the old "bulb grease" in the sockets was caked up and hardened and blocking the signal. I took out the wiring harness first, and checked all the wires with a multi-meter, and found no faults. Dug that old grease out and put just a little fresh grease in there, and everything worked perfectly. I was glad it was something so simple. I apologize for being nearly a year responding back to this, I just thought I'd mention it in case someone else reads this topic with a similar issue and needed something else to check.