1970 turn signals stop working when headlights are turned on.

[Paul70bird]

My 1970 Bird's turn signals work great all day but when it got dark and I turned on the headlights (which work fine) they stopped working both front and rear turn signal. Where should I start to figure this out.
Thank you

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[cougarsunlimited]

My 1970 Bird's turn signals work great all day but when it got dark and I turned on the headlights (which work fine) they stopped working both front and rear turn signal. Where should I start to figure this out.
Thank you

Does your T-Bird have the original green or red flasher can (marked 4-lamp sequential trigger)?
If so, it may have aged so that it needs more current to flash than when new.
The headlights draw enough additional current so that a weak charging system or battery cannot provide enough current.
The original alternator barely provides enough for the headlights, turn signals, ignition, heater/AC fan, and accessory requirements.

Try replacing the flasher can with a new electronic flasher, such as the D0WY-13350-AR.

 

[Paul70bird]

Vic, thank you so much for the lead on finding a fix for this problem. I have ordered the flasher and will see if this solves the problem.
Paul Curry