How does the igniter know when to fire the coil on an 81 pickup? I can find no ecm or ecu. I notice in the fsm using a 1.5 volt battery to test the power transistor. What does this test provide as far as ankowledge of what is possibly wrong wth the transistor? Does it produce a spark? There is no meter attached in the diagrahm.

 

The signal to the ignitor comes from the wire that is attached to the magnetic pickup coil inside the distributor.

 

That is my understanding as well. Is there another fuse or relay for the 81 besides the under dash fuse box for the engine? I see nothing in the fsm.