Wiring dashboard turn signal indicator

[forestb]

I am having a wiring harness installed but we are having problems with only having one light on the dash board that tells you the blinker is working and having two wires. If both wires are connected to the single bulb both rear turn signals blink at the same time. If they are unplugged they work correctly. How can I solve this?

[jtrichard]

You need a socket that is NOT grounded and has 2 wires on it hook one to the left and the other to the right (front) signals... That is how OEM did it .... indicator bulb will ground through what ever front bulb is NOT being used but will not pass enough current to light that bulb.

Wiring Diagram in this thread shows it http://67-72chevytrucks.com/vboard/s...d.php?t=499476

Another way to do it would be use diodes at the indicator socket

[forestb]

Thanks. That is what I have done. The guy that is installing the wiring said that the current was strong enough to cause both sides to blink. The tail lights are led so maybe the smallest amount of current can light it up. Maybe I need the electric type blinker switch instead on the macanical. I had one on their before but he might have changed it.

[jtrichard]

IT HAS to be hooked to the front NOT rear and LED in the front may be a problem if so then diodes are the answer

[Tazimafied]

Both lights are blinking because your harness must have been made to operate two separate indicator lights. The only way to solve this one is to run two indicator lights.

[jtrichard]

TAZ in a 63 they only used ONE indicator lamp and a two prong flasher the indicator lamp has 2 wires to it one from the LT front and one from the RT front and NO ground IF you can read a wiring diagram go up to post #2 and click on the link I posted and you will find a 63 wiring diagram and it will show this ... YES two indicator lamps would work but that is NOT the ONLY way to fix his situation

[Tazimafied]

JT,

I had an epiphany this morning and you are correct. I just didn't think it through before I posted. Two lights are not the only way to solve this dilemma. One way is as stated that there were two hot wires going to the indicator bulb which would mean the bulb was a dual filament bulb or it had internal diodes of some sort. There are a few restoration catalogs to order the original bulb from if you want to go that route. If you are using an aftermarket setup like a single LED you would need to install a diode in line on each wire before the light. This would prevent power bleeding back in to the other lamps on the truck. Just make sure the diodes can handle the amperage they will be subjected to. This option would give an easy install and clean look.

[jtrichard]

Originally Posted by Tazimafied

JT,

I had an epiphany this morning and you are correct. I just didn't think it through before I posted. Two lights are not the only way to solve this dilemma. One way is as stated that there were two hot wires going to the indicator bulb which would mean the bulb was a dual filament bulb or it had internal diodes of some sort.

Not to be an ASS but No only a single filament bulb With a FLOATING ground ....Link below is the Best thing i found to explain this (pages 1 and 2)...I know its for a motorcycle but the same basics DISREGARD THE REAR turn lights in this diagram.... IT further goes on to explain what needs to be done when LEDs are installed in the front turn/park lights

https://www.customdynamics.com/pdf/M...ch%20sheet.pdf


One reason GM did this is that when one of the front bulbs blows (lets say the right) then the indicator will NOT flash when in left turn mode BUT will in right turn telling you that a bulb is OUT..... THIS does make trouble shooting fun sometimes LOL

[Tazimafied]

That whole floating ground thing is a mind blower. I've never dealt with that before and thought Forest was doing some crazy aftermarket stuff at first. Thanks for explaining it further. I love the challenge of figuring out circuits and now have a bit more knowledge to help in the future.

[jtrichard]

IT works because the indicator bulb wattage is much lower than the front turn bulb so the front bulb filament acts like a wire and will NOT light because the voltage is limited by the dash bulb ........ GM used this type system for side blinker/markers starting in 73 I be-live