1966 fender indicator lights working oddly

[Al63]

Hi everyone

The turn signals on my 66 work properly, except the indicator lights on the fenders.
Instead of blinking normaly with the usual tic-toc sound, they either stay on without a sound or they blink erraticly.
It is more often when the lights are on or when the brake lights are on.
Any idea?
Thanks
Alain

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[paul5456]

Make sure they are grounded good. Erratic problems with lights usually indicate a bad ground. To test this, make up a wire with clips at the ends. Attach one end to the lamp housing and a good ground. If this fixes it, remove them, clean off all mating surfaces and when reinstalling them make sure that the mounting screw/bolts are on some bare metal.

 

[Ward 57]

Make sure they are grounded good. Erratic problems with lights usually indicate a bad ground. To test this, make up a wire with clips at the ends. Attach one end to the lamp housing and a good ground. If this fixes it, remove them, clean off all mating surfaces and when reinstalling them make sure that the mounting screw/bolts are on some bare metal.

Don't forget the di-electric grease.

 

[cougarsunlimited]

Hi everyone

The turn signals on my 66 work properly, except the indicator lights on the fenders.
Instead of blinking normaly with the usual tic-toc sound, they either stay on without a sound or they blink erraticly.
It is more often when the lights are on or when the brake lights are on.
Any idea?
Thanks
Alain

This is a common problem with the 1965-68 Thunderbirds. The indicator relay, which provides the "tic-toc" sound, is current sensitive, i.e. it clicks based on the amount current feeding to the turn signal bulbs. Potential problem areas that can reduce this current:
1. A weak charging system or battery
2. Resistance built up in the turn signal switch contacts
3. Poor or corroded harness connections
4. Corrosion in the light bulb sockets
It is most evident when the brake lights, headlights, and/or A/C are on. Typically, one flash may occur and then the light stays on.
I believe another cause is that the metal spring arm for the relay work hardens over years of usage and causes the relay to go out of calibration.

First: check your charging system.
Second: make sure all the bulbs and sockets (front and rear) are working correctly.

Because of this problem and since LED lights became popular, I developed an indicator relay replacement that has much more sensitivity with a special circuit that allows it to detect low current LEDs yet still work with higher current incandescent bulbs:
1965-1967 Thunderbirds C5SZ-13A366-CR
1968-1969 (11/6/67-10/15/68) Thunderbirds C8SZ-13A366-DR