Turn Signal problem

[Flip Smiley]

My turn signals are only working at higher RPM. They work when pulling up to a stop light but stop at slower speed or idle. This is a stock 1990 5.0 setup, alternator, battery with dieted harness. Good grounds all around, 4 corners on the light harness etc. MK2, new problem after 18 years and many trouble free miles. Battery seams OK and all other electrical works fine including emergency 4 way flashers even at low or no rpm.
Thanks for your consideration of my issue.
Phil

[edwardb]

If you're convinced the battery and charging circuit are working properly, e.g. don't drop voltage at low RPM (not an uncommon problem) have you tried replacing the flasher in the fuse panel? Maybe it's getting tired. A little more money, but a solid state flasher (vs. the usual thermal style) would maybe give best performance. They're basically mandatory for LED setups. But work OK for incandescents too.

[Flip Smiley]

Yes you are correct. I checked battery voltage, drop on start voltage, alternator output voltage and ground to frame at all corners. Changed out the flasher and all is good. Thanks as always for your help!
Phil