1. With ignition switch in "OFF" position, disconnect ignition coil connector. Inspect connector for dirt, corrosion or damage. Measure resistance across ignition coil positive and negative terminals. See Fig. 4 . 2. Resistance should measure .3-1.0 ohm. If so, ignition coil primary circuit is okay. Proceed to IGNITION COIL SECONDARY RESISTANCE test. If resistance is less than .3 ohm or greater than one ohm, replace ignition coil. IGNITION COIL SECONDARY RESISTANCE 1. With ignition switch in "OFF" position, disconnect ignition coil connector and secondary wire from coil tower. Measure resistance between negative coil terminal and coil tower. See Fig. 4 . 2. Resistance should measure 6500-11,500 ohms. If so, ignition coil is okay. Proceed to WIRING HARNESS test. If resistance is less than 6500 ohms or greater than 11,500 ohms, replace ignition coil.
WIRING HARNESS 1. Disconnect wiring harness connector from ignition module. Inspect connector for dirt, corrosion or damage. Disconnect wire at "S" terminal of starter solenoid. 2. Attach negative voltmeter lead to distributor base. Measure battery voltage. With negative lead of voltmeter still connected to distributor base, check voltages at TFI-IV ignition module wiring harness terminals. See Fig. 5 . See WIRING HARNESS TEST table.
3. If all readings are at least 90% of battery voltage, wiring harness and connectors are okay. Go to STATOR test. If reading is less than 90% of battery voltage, inspect wiring harness and connectors. Also check for a worn or damaged ignition switch. Repair or replace as necessary. Turn ignition off. Remove voltmeter. Connect "S" terminal to starter solenoid. Fig. 5: Wiring Harness Test Courtesy of FORD MOTOR CO. STATOR 1. Turn ignition switch to "OFF" position. Remove and ground coil wire. Attach digital voltmeter negative lead to distributor base. Disconnect spout in-line connector near distributor. Attach positive lead to ignition module side of connector. 2. Place ignition switch in the "ON" position. Using ignition key, bump starter 4-5 times and measure voltage while engine is stationary. Allow digital voltmeter reading to stabilize before taking measurement. Record all values. 3. If lowest reading is less than 0.5 volts, replace stator assembly. If highest reading is less than 70% of battery voltage, but the lowest reading is greater than 0.5 volts, remove TFI-IV ignition module from distributor. 4. Inspect stator and TFI-IV terminals for misalignment or damage. If terminals are okay, replace stator assembly. 5. Measure resistance between TFI-IV module terminals. See Fig. 6 . Refer to the TFI-IV MODULE RESISTANCE VALUES table.
TFI-IV IGNITION MODULE 1. Disconnect "Spout" in-line connector at TFI-IV module. Connect Spark Tester (D81P-6666-A) between ignition coil and engine ground. See Fig. 7 . Crank engine and check for spark at tester. If no spark occurs, perform IGNITION COIL PRIMARY RESISTANCE test. 2. If spark occurs, check Profile Ignition Pick-Up (PIP) and ignition ground wires for continuity. Repair as necessary. If these items are okay, go to appropriate ELECTRONIC ENGINE CONTROL IV article in COMPUTERIZED ENGINE CONTROL section listed below.
Sunday, September 27th, 2009 AT 8:52 AM