Turn signal problem

[FMJ]

So my Roadster is back from paint and I proceeded to plug the lights back in. Keep in mind (to my knowledge) nothing has changed. What happens is when I put on the turn signal all four light up. I checked the wiring on all four corners and it looks correct. Any ideas?

Everything else works fine.

-Fred

[billjr212]

I had this happen once early on during assembly - for me turned out that the turn signal bulb/housing was turned a bit and caused the signal to cross with the flashers and was essentially back-feeding the other sides lights. Kind of hard to describe so hopefully that makes some sense. Maybe try unplugging 1 light at a time on the side you turn the signals on and see if it stops the other side from blinking.

[Gumball]

I would agree with backfeed. Did you use diodes to protect / isolate the flasher circuit? If so, it may be circumventing those somehow.

[FMJ]

No diodes.

Disconnected the front with no success. I'll try the back later as they are really tucked up and access is not trivial.

-Fred

[Gumball]

No diodes.

Disconnected the front with no success. I'll try the back later as they are really tucked up and access is not trivial.

-Fred

Okay - no diodes could explain the problem. Since the lights are hooked through two flashers and switches, I'm guessing that anytime you use the turn signals, the flow of electricity is going back through the flasher circuit and activating all of the lights. When I installed my flashers, I found a schematic on the forums and a how-to on diode installation on the web that isolated the flashers from the turn signals. Do a search here or at ffcars and you should be able to find what you need.

[FMJ]

I'll look for that.

The part that still confuses me is they worked before.

-Fred

[Gumball]

Are you running them through a single dash indicator light? If yes, was that connected when you did the original test or use? That is usually the culprit when having backfeed issues between the turn signals and the flashers, since the flasher circuit runs all four lights and that dash indicator, while the turn signals just run one side at a time with the same dash indicator.

Here's my thread over at ffcars, as well as another that will maybe help...

http://www.ffcars.com/forums/17-factory-five-roadsters/415017-question-about-diodes-russ-thompson-turn-signals-hazards.html

This thread has a good wiring diagram you can use to compare with how yours is wired...

http://www.ffcars.com/forums/17-factory-five-roadsters/228340-russ-thompson-turn-signal-wiring-ron-francis-harness.html

[FMJ]

I am indeed running one indicator light. Would using a left and right side indicator light help (I have a second)?

[Gumball]

So long as the two circuits are isolated from one another, diodes are not needed. As the old example goes, think of wires like pipes and electricity as water. If there is a path for the electricity to flow to another part of the system (i.e., another circuit), it will definitely do so. Diodes are like check valves that only allow the electricity to flow one way through them and not back the other way.

Check out the schematic in Post 10 of the second link above and you'll see the diode images at the dash light and at the hazard switch. Imagine the schematic without those and trace the path of how electricity would flow when the turn signal switch is placed to the "right" or "left" position. That should help you understand the circuits a bit better and figure out where the problem lies with your set-up.

Keep us posted on progress - sounds like this is a relatively easy fix. For info on how to add diodes to the system, do a search on "diode" and "EAA" - those aircraft builders have great methods and how-to instruction videos on youtube.

[Jeff Kleiner]

I'm back on American soil now Fred. As Chris mentioned the two sides must be isolated either by individual dash indicators or with a pair of diodes when using a single. I'll give you a call tomorrow.

Jeff

[FMJ]

That's it! A second dash indicator did the trick.

Thanks...

-Fred