That's the heavy-duty flasher as used on Camper Specials.
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-O-----O- Keith
'67 F-100 2WD SWB ~ '69 F-100 4WD SWB w/7" chop ~ 1975 F-250 Ranger XLT Supercab Camper Special My '67 restoration video -> Posting and you!<-a MUST watch for all!!
if you have brake lights then your turn signals are a different problem. most fo these trucks have problems in the turn signal switches when multiple lights wont work.
yes the heavy duty flasher could be causing those 3 functions from working. The emergency flasher switch on the 67's seems to be a weak spot.
The turn signal switch could also be the problem. Go ahead and try a flasher is easiest quickest test. An Ideal 552 flasher will work esp as a test unit.
Good luck and welcome to the board