Primary Circuit Test (Except Closed Bowl Distributor)

Disconnect terminal "S" at starter relay to allow testing of ignition primary circuit without cranking motor. Ensure ignition is off. Push down on connector tab and disconnect harness connector from TFI module. Ensure TFI module connector is not corroded or swollen. Repair or replace connector as necessary.
NOTE: If connector is damaged or has broken tabs due to misuse, replace connector. A loose or damaged connector may cause ignition signal faults during KOER operation.
Use a straight pin or terminal spade from an old TFI module to probe connector. Attach negative DVOM lead to distributor base. Avoid ground contact with straight pin or positive terminal lead during testing. Turn ignition on and measure voltage at following TFI module harness connector terminals: See Fig 1.
Key On Engine Cranking (KOEC)
- No. 3 (Power/Run Circuit)
  Key On Engine Off (KOEO)
- No. 4 (Start Circuit)
- No. 3 (Power/Run Circuit)
Fig 1: TFI-IV Ignition Module & Connector Terminal ID
Courtesy of FORD MOTOR CO.
Turn ignition off and remove test pin. Reconnect wire to "S" terminal on relay. If approximately 90% of Battery Voltage (VBAT) is not present at these terminals, repair open circuits in wiring harness as necessary. Check ignition switch for faults. See appropriate wiring diagram. If voltage was as specified, reconnect module and go to next step.
Attach a 12-volt test light between ground and coil negative (-)/tach terminal No. 2 at TFI module. Turn ignition on, and crank engine. If test light flashes brightly during cranking, go to appropriate PIP SENSOR/STATOR TEST. If test light stays on during cranking, check for open in coil negative circuit between coil and TFI module connector. Repair circuit as necessary. If no open circuits are found, ignition module is shorted internally. Replace TFI module and retest.
If test light is always dim or off during cranking, check voltage to coil positive (+) terminal. If voltage is not present with key on or during cranking, repair open in primary circuit between battery and coil positive (+). If light flashes intermittently, check ignition module resistance. If voltage is available at coil, go to COIL TEST and check ignition coil.