Turn Signal Woes

[aleigh]

My left rear blinker was intermittent and then finally gave up the ghost. Tail light seems to work fine. I haven't checked the brake light yet but I will as soon as I have a person to look at it. I thought that this was just a defective light unit or a bad ground until I realized it's not lighting the trailer lights either, which lead me to do some troubleshooting, and it is not energizing the trailer 24V turn signal relay for the left side. I swapped relays with known good just to be sure. So now I suppose the problem is in the dash somewhere.

I went through the TM but funny enough they don't have a troubleshooting procedure for rear-only turn signals (but they do for front turn-only problems). I haven't started dragging myself through the electrical schematics yet, but I am posting in case someone else has run into this problem already and can steer me the right way. My guess is the flasher module is okay since the fronts work?

EDIT -- Solved. Dashboard warning light module cable was loose.

 

[coachgeo]

ground fault? One could possibly apply the concepts of the "front turn-only problems" in the TM, to diagnosing the rear?

 

[snowtrac nome]

I would look strongly at the switch sounds like a burnt contact. There are other causes but your most likely problem would originate from where you have moving parts.

 

[coachgeo]

I would look strongly at the switch sounds like a burnt contact. There are other causes but your most likely problem would originate from where you have moving parts.

wouldn't that affect front and rear equally? His is a rear ONLY issue.

 

[aleigh]

Thanks for the tips. I am about to go through the schematics and I'll get into the dash tomorrow probably.

 

[snowtrac nome]

wouldn't that affect front and rear equally? His is a rear ONLY issue.

No power flows into the switch from the flasher, than goes through a set of contacts one for the front, and the other flows through a set of contacts that energizes the rearsignal circuit at the same time de energizing the brake light circuit.

 

[snowtrac nome]

to check the brake lights turn on your 4 ways if they all work normal step on your brakes your flasher should stop flashing now you know the lighting circuit is working and the brake light switch functions.

 

[Suprman]

It's almost always the stalk control. One blinker not working is common.

 

[aleigh]

Resolved this today. I should mention before I get to the punch line that prior to failing to work the turn signal had been dim (the tail light was normal brightness and the turn bright was "weak" compared to the other composite lights). Also that I was leery about it being the stalk because the hazards didn't work either. I mean they worked, but not the rear left side or trailer.

I had been having problems with my dashboard display light panel (the warning lights). Some flickering. A few days ago the panel went all sideways and I lost everything except the turn signal lights and the high beam indicator. No air brake warning, and the alarm was silenced (hard to say if that is a feature or a bug). Anyways I figure great bad grounds all around, and I get in there half expecting a mouse nest.

No, the cable was just coming off the display panel. I pushed it back in and presto everything started working... Including for whatever reason the left rear turn signal circuit. It seems odd that would be affected especially since the left turn light indicator light was working, but I am not complaining. Oh, and the tail is full brightness now. I didn't even have to take the dash panel off - just the warning light module.

Mystery solved, and now I can safely leave tomorrow for Washington.