running lights and turn signals

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=108815
Printed Date: November 03, 2025 at 9:10 PM

Topic: running lights and turn signals

Posted By: allen newton
Subject: running lights and turn signals
Date Posted: November 10, 2008 at 7:57 PM

I'm putting together a 1937 plymouth coupe, it didn't come with running lights or turn signals on the front of the car. We made up some LED's lights to use. How do I wire the light so the LED's will light when the running lights are on and flash when the turn signal is on and also flash when the running lights are off.

Currently I have three wires in the headlight bucket, ground, left turn, and running.

Thanks,

Allen

Replies:

Posted By: reax222
Date Posted: November 11, 2008 at 2:54 AM

LED's are polarity sensitive so you can't flip the power on them. I looked at doing this with relays, but I couldn't work it out with just two. However it looks like it's doable with diodes. Tie both the parking and turn signal wires to both leads and use diodes to control polarity. So when the parking lights are on, turns off, positive flows from the parking lights to turn signal. When the parking lights are on and the turn signals are on, you have no ground so the leds aren't illuminated. When you have the parking lights off and turn signals on, positive flows from the turn signal to the parking light wire. With both off, there is no positive.

Assuming both wires are hot when active. posted_image

Posted By: allen newton
Date Posted: November 11, 2008 at 9:23 AM

Great,

I'll give it a try today.

Thanks,

Allen

Posted By: ckeeler
Date Posted: November 11, 2008 at 10:05 AM

you CAN do this with a relay. i wrote up on this site how to do it for another guy that wanted to flash the LED marker lamps on his tow truck when he flipped a switch. you need 2 relays, one for each side of the car, and 2 LED flashers, one for each side of the car. they must be LED flashers as a standard flasher wont work with LED lights. use the below diagram. you need to use this setup twice, one for each side, left and right

posted_image

Posted By: allen newton
Date Posted: November 11, 2008 at 4:26 PM

With the diagram using the relays, two questions-

1) Since I using the normal 1157 rear lights should the standard flasher work?

2) I'm a dummy, on the diagram what is the circle to the upper left with X and L in it?

Thanks for all of the help!

Allen

Posted By: ckeeler
Date Posted: November 11, 2008 at 4:38 PM

oh your not a dummy. i guess i didnt explain good enough. the circle is the flasher. and yes if you have standard bulbs in the back this will work fine with a standard flasher. for some reason i thought you had all LED's.

Posted By: ckeeler
Date Posted: November 11, 2008 at 4:47 PM

question: did you install a modern fuse box with new style fuses in it with the built in socket for a flasher like from painless wiring or some other hot rod aftermarket harness company? if so, i can give you another diagram to use that built in flasher.

Posted By: allen newton
Date Posted: November 11, 2008 at 5:26 PM

Yes, by memory it's a ron francis kit.

Thanks

Posted By: reax222
Date Posted: November 11, 2008 at 5:52 PM

I passed on that diagram because you have to catch power between the turn signal switch and the flasher. I'd like to see the other diagram as well.

Posted By: ckeeler
Date Posted: November 11, 2008 at 5:54 PM

allen newton wrote:

Yes, by memory it's a ron francis kit.

Thanks

can you give me the part number of your kit?

Posted By: allen newton
Date Posted: November 11, 2008 at 9:35 PM

It's a haywire kit, it's called a 7 fuse kit, there was no part number on the box. I think I bought it at a local swapmeet years ago and can't find the paperwork :).

Posted By: allen newton
Date Posted: November 15, 2008 at 2:07 PM

I connect this up and it almost works :). If i test (only connect) the 12v from the flasher to one of the lights it works great (both lights), since both of the turn signals work out of the same flasher when I connect both "x" leads to 85 on each of the relays nothing works.

Any advice?
Thanks

Posted By: ckeeler
Date Posted: November 17, 2008 at 8:45 AM

Thats because a flasher wont triger a relay coil. you have to get power for treminal 85 from the turn signal switch BEFORE the flasher like in the diagram i posted.