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Turn Signals Blinking Waaay Too Fast!

stxbronco72

Contributor
Jr. Member
Joined
Jan 9, 2012
Messages
166
Loc.
Corpus Christi
I have my turn signals working, but they are flashing about as fast as a strobe light... All four (front and rear, drive and passenger sides) are working but behaving like this. Any thoughts?

Note: This is stock 1972 wiring.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
35,710
Replace the flasher. They do go bad. I had one get water in it once and it rusted internally a little and started acting like that.
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,347
The one with the light blue colored connector is the one for the turn signals.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
35,710
Newer computer controlled blinkers sense the load and will rapid blink when a bulb is out. Old blinker cans tend to stop blinking (just stay on) when a bulb is out. But this applies to OEM blinkers that are load matched. The replacements are not as load sensitive.

Back in the day when you plugged in a trailer the blinkers wouldn't be happy with the extra load. The quick fix was to swap the hazard and turn flasher cans. This would give normal turn but the hazards would be all screwed up. The typical heavy duty flasher didn't care about the load and was a better fix.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
49,460
To test the theory of a bad flasher (likely true, but a quick test is easy) is to simply swap the hazard flasher for the turn signal flasher to see if it changes the characteristics. If so, you know you're on the right path.

You already said that all four turn signals were working, so it would seem you walked around the truck and verified this visually. Which means it wouldn't be a bulb issue.

Two of my '60's GM vehicles (a Chevy and a Buick) would tell you which bulb was out actually. If a front bulb burned out, the flasher would double it's speed. If a rear burned out, it did what was mentioned above and stop blinking altogether. Weird, but consistent over many years and several bulbs.

Paul
 
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