Pick-Up Coil: Description and Operation

Ignition System Components:

Magnetic Pick-Up Assembly:

HEI Wiring Diagram:

The pick up coil is a device, located in the distributor, that generates an alternating current signal to determine crankshaft position. The ignition module then shapes this signal into a square wave and sends it to the PCM. These reference pulses are used by the PCM to determine crankshaft position and engine rpm. PCM code 12 will set if the PCM receives cam sensor pulses without receiving reference pulses.

The magnetic pick-up assembly located inside the distributor consists of a permanent magnet, a pole piece with internal teeth, and a pick-up coil. When the teeth of the timer core, rotating inside the pole piece, line up with the teeth of the pole piece, an induced voltage in the pick-up coil signals the electronic module to trigger the coil primary circuit. The primary current decreases and a high voltage is induced in the ignition coil secondary winding which is directed through the rotor and secondary leads to fire the spark plugs. The capacitor in the distributor is for radio noise suppression.