Hey All, would really appreciate some help as I am electrically challenged. I installed a LED light bar on my 85SE. The light bar contains turn, brake, hazard, running, & backup functions. Right turn, left turn, brake, hazard all work perfectly as long as the running lights are NOT on. With the running lights on I have NO hazard or turn. After some testing I found that the turn signal wires (front and rear) show approximately 6V when the running lights are turned on and 0V when running lights are off. I think it is this 6 volts that is messing up the light bar. I reviewed the wiring diagrams for the SE and can't see how there could be voltage on those wires unless the turn signal or hazard is on. Oh, and yes, i have the correct blinker for LEDs
Thanks DB, I'll re-check the grounds. This morning I am going to check voltage at the column and see if I get the same readings coming out of the turn signal switch itself as I did at the bar connections. What's really throwing the trouble shooting is 1) why is there voltage on a turn signal wire but only when the running lights are on and 2) why is the voltage different from driver to passenger side. Ughh!
Update - noticed the driver and passenger rear side marker lamps were not lit. After messing with the drivers side (wiggle bulb, etc) the bulb lit as did the passenger side. Then checked the voltage on the turn signal wires at the rear, both are now at .39 volts when the running lights are turned on. I am thinking the little bit of voltage is messing with the light bar electronics. I still can't get turn or hazard to work when the running lights are on.
[This message has been edited by michfiero1 (edited 08-24-2025).]
Thanks DB, I'll re-check the grounds. This morning I am going to check voltage at the column and see if I get the same readings coming out of the turn signal switch itself as I did at the bar connections. What's really throwing the trouble shooting is 1) why is there voltage on a turn signal wire but only when the running lights are on and 2) why is the voltage different from driver to passenger side. Ughh!
When the ground for the light harness or a bulb here and there aren't making good contact, sometimes the circuit will 'find' a ground back through one of the bulb filaments and do wonky things.
The latest - with all incandescent side marker lamps working, I was able to get the front LED turn signals (light bar, not bulbs) to work even though there is still a residual 6 volts at the front turn signals when signals are off and running lights are on. It would appear the front LED turn signals aren't impacted by the residual 6V. So, I now have front turn signals when the running lights are on or off. With the front signals now working I ran a long wire from the front signals to a different light bar in the rear and in this way I have front and rear turn signals with running lights on or off. I believe the front signals work because there are no electronics in them whereas the light bar in the rear does.
I still think the residual voltage on the turn signal wires is the culprit (6v up front, .39v in the rear) when the running lights are on. I can't figure out where a sneak power or ground circuit could be to cause this. I don't like the idea of running the long wires but it appears I have no choice.
Any other theories as to why there would be voltage on turn signal wires (with signals off) and running lights on?
[This message has been edited by michfiero1 (edited 08-24-2025).]
The latest - with all incandescent side marker lamps working, I was able to get the front LED turn signals (light bar, not bulbs) to work even though here is still a residual 6 volts at the front turn signals when signals are off and running lights are on. It would appear the front LED turn signals aren't impacted by the residual 6V. So, I now have front turn signals when the running lights are on or off. With the front signals now working I ran a long wire from the front signals to a different light bar in the rear and in this way I have front and rear turn signals with running lights on or off. I believe the front signals work because there are no electronics in them whereas the light bar in the rear does.
I still think the residual voltage on the turn signal wires is the culprit (6v up front, .39v in the rear) when the running lights are on. I can't figure out where a sneak power or ground circuit could be to cause this. I don't like the idea of running the long wires but it appears I have no choice.
Any other theories as to why there would be voltage on turn signal wires (with signals off) and running lights on?
I’m no auto electrician but when I installed switchback LEDs in my front turn signals to comply with Australian Design Rules for motor vehicles, I had to install a ballast resistor on each circuit to get the signal to blink properly and to prevent the turn signal arrows on the instrument panel from illuminating dimly when the signals were not in use. The 10-watt resistor on each circuit was enough reduce the voltage and make the signals operate properly. My guess is that the long wire you installed is acting like a ballast resistor. Installing an actual ballast resistor may be warranted.
Mike, many thanks for the info. You and DB have given me some great advice. Now, where did I put that 10W resistor!? Just kidding, i actually just might have some from a different electronics project. We used to have Radio Shack here which was great for all things electronic, but, none around anymore. I'll post how it goes.
Before you do all that mechanical replace the flasher unit with a LED compatible flasher. The reason you are seeing lower voltages is because the LED's do not pull enough amperage to make that old mechanical flasher work properly..
[This message has been edited by jelly2m8 (edited 08-25-2025).]
Before you do all that mechanical replace the flasher unit with a LED compatible flasher. The reason you are seeing lower voltages is because the LED's do not pull enough amperage to make that old mechanical flasher work properly..
Before you do all that mechanical replace the flasher unit with a LED compatible flasher. The reason you are seeing lower voltages is because the LED's do not pull enough amperage to make that old mechanical flasher work properly..
He already has a correct flasher, as mentioned in the first post.
I think the reason you have 6v when parking lights are on is not a bug, instead is how it's designed. If you look at the ogres cave, led marker light page, there's a diagram of the electrical path, because the front marker light is a single filament and has to handle both turn and parking lights, it uses the front turn filament as a ground, when parking lights are on and the front turn filament is on the side bulb has no ground (turns off), when the parking lights are on and no turn, the electricity goes through both the side marker light and the front turn filament, which is to large to illuminate, instead just acting as a ground for the side bulb, but it would see voltage.
[This message has been edited by 1985 Fiero GT (edited 08-25-2025).]
Thanks again for the help, I believe the problem has been solved.
As 85GT surmised there is indeed a sneak path from the running light circuit to the turn signal/stop/hazard circuit. I haven't figured out the path yet but here's what happened, with a re-cap.
After installing a light bar on the rear for stop/hazard/run/backup functions I could not get the turn signals to work if the running lights were on. After some circuit testing it turns out that with the running lights on there was ~6V on the turn signal circuits. This was enough to confuse the electronics in the rear light bar. Following up on GT85's posting, I removed the bulbs from the front driver and passenger side marker lights and now there is no voltage on the turn signal circuit when the running lights are on. This means I now have all the rear lighting functions working, although I do have to solve the front side marker light issue (but that doesn't appear to be a big deal).
