Problem With Signal Dynamic Self Canceling Turn Signals

[342Stroker]

I need some help. I have a Mk III that I bought about 9 yrs ago and was proceeding nicely with the build ( about 75% completed), then life got in the way. So after about 5 years of no activity I back to getting it finished. Back then I installed a Signal Dynamics Self cancelling turn signal module. Upon completion I checked it out and everything worked as it should, even the 4 ways. A couple of notes on the install: I installed a double pole momentary switch to activate the left & right turn signals off the same switch. I also installed a signal pole momentary switch to work in conjunction with the turn signal switch to activate the 4 way flasher. I added a second green turn indicator dash light so left & right turn signals each has their own indicator light. Unrelated to the turn signals per se, but adds to problem symptoms, the blue high beam indicator light is functional. As I said when I originally wired it up all worked as it should have. The main wire harness is the Ron Francis one that came with the car. When I went to check out the circuit yesterday everything kind of a whet to hell. First, let me say that when I activate the right turn signal using the momentary switch all works fine as designed, When I activate the left turn signal from the switch both left & right, front & rear lights flash, along with all three dash indicator lights (2 green and the blue), and the instrument lights flash. I hate to start tearing wires out because everything worked before and no changes have been made electrically. I thought maybe it was a ground problem but checked those and they are OK (checked with ohm meter). I even tried running a separate ground, no change. I'm thinking maybe I'm getting a back feed but don't know where to start in looking for it.

Any thoughts or help would be greatly appreciated. I need to get it resolved before I can move on. Getting closer to completion!

Paul

[Boydster]

I would start by checking all the bulbs closely. Its been sitting a while, so the slightest bit of corrosion or a mis-seated bulb could cause feedback to other circuits. Also, the fact that it works one way but not the other would really lend me to suspect the SD unit.

[DadofThree]

Attached is how I wired up my Signal Dynamics Penta Star XP module.

I would have thought it would be a ground too. Sorry can't help on that, but maybe you'll see something different in the wiring. I added Diodes all over the place, but am using ONE green lamp for both directions. I too am using a single switch with 2 momentary positions (ON) - OFF - (ON)

Also did the same thing with the hazard, but don't have that shown in the schematic. sorry.

HTH somehow.

(will copy and paste on other forum)

[342Stroker]

Well I thought I follow up and let everyone know what the problem was. Maybe it will same someone else a lot of time and aggravation. I spent about 20 hours troubleshooting and second guessing everything I'd originally done. Even though it was a long time before I got back to working on it, I knew I would have never buttoned all the electrical up if it didn't work properly. So I started with grounds. Even ran a direct ground all the way back to the battery. Tried separating grounds. starting cutting wires and eliminating light circuits one by one, replace the signal dynamics module. Nothing changed the problem. So I disconnected the left bottom tail light (that is the turn signal), tried the left turn signal and even though I no longer had a left rear turn signal, the front worked and the dash lights no longer flashed when the turn signal was activated. Put it back together, got the problem back. So I turn off the turn signal and turned on the running lights. I noticed the left bottom light seemed to burn a little brighter than the others. I removed the lens and noticed both filaments were lit. I removed the bulb and inspected the socket and found that the two contact points in the socket has welded themselves together. Took my Dremel and separated the two contacts and created a gap between them, put the bulb back in and everything worked as it should have. Now I have a few days work soldering all the wires back together that I separated, and reassembling the dash. The only comforting aspect was knowing that I had it wired properly from the start.

[phileas_fogg]

I'm glad you found what was causing the problem. Do you know what caused the contact points to weld themselves together?


John

[Boydster]

I was actually right about something for once! Yay!! Just kidding, glad ya found it.