Triumph Repair: 1976 Spitfire Signal Problems, turn signal flasher, flasher units

Question
I recently installed a new signal switch assembly to repair a broken signal lever.  The exterior lights and dash indicator illuminate but do not flash.  Can you suggest a remedy?  Also, how do you test the flasher unit?

Answer
Hi Craig,
The flasher works on the resistance of the bulbs. Meaning that the load of the bulbs heats up a bimetal strip in the flasher unit and that bimetal strip warps and disconnects the circuit. The strip quickly cools and reconnects the circuit. All current that goes to the bulbs must go through the flasher unit. Later models added a 4 way flasher system which adds another power supply and is wired differently. The early system uses a three pin flasher unit and the later uses a two pin flasher unit.

The 76 Spitfire should have the two pin flasher. Most of the flasher units pins are labeled "B" for power supply which in your case comes from the 4 way flasher switch. The other pin is labeled "L" which is the load (switch and bulbs)
If you have it wired wrong your power supply may be coming from some other source so do this.

Unplug the flasher unit and the turn signal lights should not operate. If that is the case you just have a bad flasher unit. The 4 way flasher unit looks the same as the turn signal flasher unit.
Howard