87 left brake light (maybe turn signal) very intermittent INOP

[87MJJeep]

I just recently installed a certain taillight upgrade that I won't name by name, so anyone searching that brand will not see an issue associated with it.  I am 110% sure they are fine, and the issue is in my truck.  I think the SUPER BRIGHTNESS of the upgrade has made me realize I have an intermittent INOP driver side tail light.  It's so intermittent, I cannot test the turn signal.  

 

I can press the pedal and the light brake light will illuminate then go out.  Sometimes I can press the pedal and no brake light.  Let off and press again, and it it lights.  The last time it failed to light, I quickly turned on the parking lights, and they lit up with the brake light still out.  For this reason, I am very confident the grounding is OK.  Visually, the ground wires look fine, too.  A multimeter gets a strong beep testing the ground terminal against the ground screw.  This makes me think the issue is the 12V source for the taillights.  

 

Twice while laying under it with a the brake pedal pressed by a helper, the brake light would dim and sorta flicker as long as the pedal was not released.  But usually it's either full intensity or doesn't light at all. 

 

While the pedal was pressed, I wiggled and tugged on all wiring at both taillights and in between running across the back of the bed.  That didn't cause any INOP.  

 

I saw a post by Ohm in this thread:

 

 

"Each bulb in each red lens compartment is a two (2) filament bulb. One filament of each bulb is for tail light circuit, the other filament is shared between the turn signal and the brake light.

 

The turn signal switch (steering wheel) determines which function it will be, a turn signal circuit or a brake light circuit."

 

I saw another post here I forgot to bookmark making reference to the brake pedal switch.  Could it be the brake pedal switch affecting just one side in the rear?  Then the above post makes me wonder is the turn signal switch failing and affecting just the driver side taillight?  

 

After messing with it last night, I went for a ~25 minute drive.  It was dark enough and those new lights are SO BRIGHT, I could tell every time I pressed the brake pedal, it lit up.  That's how intermittent it is.  

[87MJJeep]

Well, that was quick...

 

Just as I clicked to post the thread, I had a thought.  I have this old school "CarGuard" removable steering column collar.  It was bought in 1996 for my mom's 84 Buick Century.  Thanks to Jeep using GM columns, it is the same P/N for XJ and MJs.  Guess what will sometimes fall onto my turn signal lever when I remove it?  

 

So, I went out there and pressed the brake pedal.  Tapped the signal stalk for a left turn and out went the brake light as expected.  The brake light wouldn't come back on until I pushed the stalk upward a tad as if I was starting to give a right turn signal.  

 

So, how hard is it to replace this stalk?  Does steering wheel have to come off?  Any recommendations on what brand to buy?  

[cruiser54]

It's not the stalk. It's the turn signal switch inside the column. 

 

It could be as simple as a broken spring that is available separately and much easier to replace. . 

[schardein]

The stalk itself just pulls out, simple as that, if it doesn't have cruise control switches on it.  If it does, the stalk still just pulls out, but the cruise control wiring is snaked down through the column, and generally you have to pull the steering wheel and lock plate to gain access to snake in the new one.

 

The stalk itself plugs into (and pulls out of) the front windshield wipers switch which is inside the column.

 

But as Crusier mentioned, the stalk isn't the problem.  It's probably the turn signal switch as he said.

 

Before you found the likely culprit, I was going to suggest checking the electrical connector for the turn signal switch.  It is on the pass side of the steering column, just behind the dash panel.   It is clipped into a bracket on the side of the column. That connector will have to be disconnected and the harness snaked out of the column if you end up having to replace the entire turn signal switch assembly.  

[87MJJeep]

I appreciate the replies.  I assumed the stalk and switch were one part.  I've never been in a column before.  

 

I've also noticed my intermittent backup lights root cause is connected to the shift column/switch, and not a loose wire in the back.  I can wiggle the column shift a little to get them to turn on/off while in the approximate Reverse position.  I guess I'll kill two birds while in the column.