1975 turn signals
Thread Starter
7th Gear
Joined: Aug 2009
Posts: 7
Likes: 0
From: Regina Saskatchewan
1975 turn signals
I have a 75 corvette that I am working on. I put brand new wiring harnesses throughout the entire car. I upgraded to LED lights all the way around the car. I've got LED flashers and just replaced the turn signal switch in the steering column.
The issue I am having is when I put the right turn signal on, the right signals flash properly but when I put the left turn signal on and the front left, rear left and the rear right signal flash. Not sure why the right rear is flashing with the left side signals. Any insight or help appreciated.
I'm stumped on this one. All new wiring, flashers and bulbs.
The issue I am having is when I put the right turn signal on, the right signals flash properly but when I put the left turn signal on and the front left, rear left and the rear right signal flash. Not sure why the right rear is flashing with the left side signals. Any insight or help appreciated.
I'm stumped on this one. All new wiring, flashers and bulbs.
Melting Slicks
Joined: Sep 2006
Posts: 2,814
Likes: 469
From: Wichita Kansas
Is there a chance that you checked the operation of all your lights after you did the wiring harness but before you changed to LED? If you did you would at least know it was the LEDs; if not, the problem could be either the LEDs or the new harness. Someone will be along shortly to help you.
Thread Starter
7th Gear
Joined: Aug 2009
Posts: 7
Likes: 0
From: Regina Saskatchewan
Is there a chance that you checked the operation of all your lights after you did the wiring harness but before you changed to LED? If you did you would at least know it was the LEDs; if not, the problem could be either the LEDs or the new harness. Someone will be along shortly to help you.
Edit** switched just the rear lights to incandescent bulbs and turn signals work properly all the way around. Fronts are still LED. Could it be the type oglf LED bulb or would it need a load resistor installed to run LED bulbs in the back?
Last edited by Corvettekid12; Jul 4, 2023 at 01:50 PM.
Melting Slicks
Joined: Feb 2018
Posts: 2,326
Likes: 721
From: Marietta GA
I am not 100 % sure for the 1975 model year, but on my 1973 the front turn signals and the amber side lights are wired so that LEDs will give you troubles. You may want to look at a wiring schematic. After installing LEDs on my car, the green turn signal indicator lights stayed on when I pulled out the headlight switch. I kept the LEDs in the side markers, but put the old incandescent bulbs in all front and rear lamps. I didn’t think it would be wise to start splicing into 50 year old cables, they are not in great shape.
Thread Starter
7th Gear
Joined: Aug 2009
Posts: 7
Likes: 0
From: Regina Saskatchewan
I ended up switching the brake/turn signals and the front turn signals to incandescent bulbs, and all the rest are still LED. Everything works properly now. I guess the older cars just don't like LED turn signals.
Melting Slicks
Joined: Feb 2018
Posts: 2,326
Likes: 721
From: Marietta GA
The old cars don’t know that you are using LEDs. The problem is that LEDs are polarity sensitive devices (like a battery), so they will only illuminate when the positive is connected to the correct input. Even though I purchased LEDs that are NOT Polarity Sensitive, they would not work. The older car exterior light circuits were designed so the bulbs can illuminate with the positive on either input. On Newer cars with LEDs, engineers designed circuits for LEDs, where the positive input never changes. I hope this helps. For interior illumination LEDs work extremely well, they are bright, last a long time, and most importantly, don’t get hot like incandescent bulbs. The Bad new is that on older cars, the interior LEDs won’t dim.
