Help needed to determine ignition failure

[Frank C Nash]

My 1983 BMW 633 won't start. I have searched the catalog for parts but am unfamiliar with "impulse transmitter". What is it's function and where is it located on vehicle.
Car has run trouble free for years - then ran a little rough at idle for a week. I shut it off Saturday and it won't start. The coil wire was bad, no continuity, so I repaired it. No start. There is no spark. I checked the coil for resistance and believe it's OK. One of the impulse transmitters separated from the plug about a year ago causing the car not to start. Car started after I reconnected plug. I checked the plugs because the symptons were similiar. I don't know how to check impulse transmitters. When I turn the engine over with starter there is no movement on the tach. I also noticed the alternator light fails to come on when ignition is in on or start position. Can anyone help with a protocol to follow to determine ignition failure? I don't want to buy unnecessary parts. Thank you.