Ignition (Hall) Control Unit (Federal Only)

Ignition (Hall) Control Unit:

PURPOSE AND LOCATION
The ignition (Hall) control unit functions as an electronic switch that opens and closes the coil primary ground connection to control the current in the ignition coil. This function is comparable to the operation of the points in a mechanical ignition system. The control unit is located beneath the instrument panel to the right of the glove compartment with the Digifant control unit.

NOTE: Although the name "ignition (Hall) control unit" implies a component with processing abilities, this control unit has no such function. It is strictly a switching device.

OPERATION AND SIGNAL
The ignition (Hall) control unit consists of a power transistor and integrated circuit. It is used to make and break the primary circuit, and to regulate the current through the ignition coil. It receives a triggering signal from the ECU. The ECU applies power to the output stage, which turns it ON. In this ON state, current flows through the primary circuit of the ignition coil. When the ECU determines it's time for a spark, the power to the output stage is momentarily interrupted. The transistor turns OFF, breaking the primary circuit, and inducing a high voltage spark in the secondary circuit. The ECU regulates the duration of the interruption in the trigger signal, and thus regulates the dwell angle, and charging time. The longer the interruption, the smaller the dwell angle and the shorter the charge time.

Since the ignition (Hall) control unit generates heat, the unit is mounted on a heat sink attached to the body for adequate cooling. A good contact between the unit and heat sink is necessary for reliable operation of the ignition (Hall) control unit.