Ignition Control Module: Testing and Inspection

Hall control unit, checking

Requirement

Ignition coil OK






- Disconnect idle stabilizer plugs from control unit (squeeze plugs to release - upper arrows)
- Connect plugs together (lower arrows)






- Remove harness connector from Hall control unit
- Connect multimeter US 1119 with + (plus) to terminal 4 and with (minus) to terminal 2 in connector
- Turn ignition ON
Approximately battery voltage

If NO
- Check for wire breaks using wiring diagram and repair as necessary

- Turn ignition OFF
- Reconnect Hall control unit harness connector
- Disconnect Hall generator harness connector from ignition distributor





- Connect multimeter with + (plus) to terminal 15 and with - (minus) to terminal 1 of ignition coil
- Turn ignition ON
2 volts (min) for about 1 - 2 seconds and then drops to 0 volts

If NO
- Replace Hall control unit and ignition coil





- Touch center wire of connector on distributor briefly to ground
indicated voltage must increase briefly to 2 volts (minimum)

If NO
- Check for wire break in center wire and repair as necessary

If wire OK
- Replace Hall control unit


- Turn ignition OFF
- Connect Multimeter as follows:

Note: Two different types of Hall control units can be installed.





Fairchild, Bosch and Siemens - Hall control unit (Build #33)
- Connection A to terminal 15 (+) of ignition coil and other connection to terminal 7

Fairchild and Telefunken (AEG) - Hall central unit (Build #35)
- Connection A to ground and other connection to terminal 7

Multimeter must show approximately battery voltage

Checking procedure regardless of type:






- Touch center wire of connector on distributor briefly to ground
Indicated voltage must drop briefly below 3 volts





- Connect multimeter to outer terminals of Hall generator connector
- Turn ignition ON
Spec. = 5 volts (min)

Note: If readings are within specifications, but defect still exists, replace Hall control unit or check for wire breaks between Hall generator connector and Hall control unit; if necessary, repair.

Note:
Metal shavings or other debris between the ignition control unit and heat sink can cause stress which may damage internal circuits of the control unit:
When replacing ignition control unit, thoroughly clean heat sink before assembly.