Turn Signal Troubleshoot

[David_4x4]

Can anyone point in the right direction as to what may be up with my turn signals?

One day last month the turn signal wouldnt operate for turning left. The right side would however work without fail. Lights work at all corners of the vehicle. So couple of weeks ago we ordered a new flasher, didnt help same situation. No biggie.

Flashback to this week. I bring the M105 trailer home on the deuce when I get done with work on Tuesday. Low and behold signals working etc, like nothing ever happened. They continued to work up until the past two days. Driving the truck to a Veterans day parade left side quits working, but right side works like a champ. All lights still turn on etc.

Being a little annoyed. Once I return home I kind of poke around. Turn lights on, off etc. Nothing, same results (right side works, no left). Then when I hit the parking light, BAM! Back to like nothing ever happened. Both sides work.

So what's happening? Do I have a short or dirty connectors? Bad turn signal device in the cab? Or is this something all these truck do, and I just dont know about it, why, and the solution?

 

[Jones]

Try testing for the problem with another light switch; parking lights are the front turn signal bulbs on some circuits. Also sounds like dirty connectors or bad ground(s). When a ground starts to fail the system goes looking for another way to complete the circuit. Sometimes it finds it's way through to another ground or sometimes it goes through another component. That's why you sometimes see a turn signal flashing while another bulb near by goes dim in unison; or why your rig starts eating flasher units or on-board computers. Had a friend who replaced 5 on-board computers on his Mustang before someone discovered that the engine block to firewall ground strap had come loose.

 

[cranetruck]

The ground return is very important as stated above. I actually added a separate ground wire from the front composite light mounting screw to the fender to bypass the questionable ground provide by the mounting screw to guard to fender.

To solve the flasher sensitivity to the condition/quantity of lamps once and for all, I also installed a relay to handle the switching.
The flasher drives the relay and the relay contacts drive the lamps. One added benefit is a slightly higher voltage at the lamps (=brighter) as a result of the much lower voltage drop across the relay contact(s) as compared to the transistor inside the flasher.


Early flashers used a heavy duty SCR for switching and are less prone to failure.

 

[breelanr]

Check the contacts inside the turn signal switch, a little corrosion will cause intermittent contact. I had the same issue with "they work, they don't work, now they work again". I Cleaned the contacts with fine (320+ grit) sandpaper and no problems since. It's easy to do if you remove the switch from the steering column .

 

[chadtrees]

Check the contacts inside the turn signal switch, a little corrosion will cause intermittent contact. I had the same issue with "they work, they don't work, now they work again". I Cleaned the contacts with fine (320+ grit) sandpaper and no problems since. It's easy to do if you remove the switch from the steering column .

I have been battling my turns signals with no success. Only the driver side turn signals would work. I didn't want to just buy a flasher and lever assembly although I suspected either to be the issue. I found this post and cleaned the contacts in the lever assembly and everything is working!!!
Thanks for the helpful post!

 

[cattlerepairman]

Great that cleaning the contacts worked! The other issue is simply the lack of quality in many of the turn signal flasher units currently on the surplus market. They are fully potted and members experienced in electronic repair stated that repairing the manufacturing defects in these units is not really worth the effort it takes. Methinks that factory rejects made it onto the market....

It is easy to adapt a civy 24V flasher unit to fit the truck without any modification to the truck. Threads on this exist!
Here is a good one: https://www.steelsoldiers.com/threads/m-series-flasher-relay-civvy-conversion-how-to.134679/