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HOMESERVICE MANUALSFORD1992RANGER 2D PICKUP, 4.0 X, RWDREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - SYSTEM/COMPONENT TESTS - GASOLINEEDIS SYSTEMPINPOINT TEST C
1992 Ford Ranger 2D Pickup, 4.0 X, RWD

Pinpoint Test C

1992 Ford Ranger 2D Pickup, 4.0 X, RWDSECTION Pinpoint Test C
  1. Check Base Ignition Timing  With ignition off, install EDIS diagnostic cable to BOB, EDIS module, and coil pack. Do not connect VR sensor tee. Use EDIS "6" overlay (if available). Connect EDIS diagnostic cable negative and positive leads to battery. Set EDIS diagnostic cable box switch to "4/6 cylinder" position. Connect timing light (must be EDIS/DIS compatible). Start engine and allow it to warm up. If timing is 10+/-2 degrees BTDC when EDIS diagnostic cable SAW button is pushed, go to step 2). If timing is not as specified, proceed to step 8).
  2. Check For Advance Spark Angle  If engine timing is greater than 15 degrees BTDC when diagnostic cable SAW button is released, EDIS Ignition System is okay. Go to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for further driveability symptom diagnosis. If timing is not as specified, go to next step.
  3. Check SAW At EDIS Module  With ignition off, set DVOM on 20-volt DC scale. Start engine and measure voltage between EDIS diagnostic cable SAW DETECTOR (21) and BAT- (7) at BOB. If DC voltage reading is 5-7 volts, replace EDIS module. SAW input to EDIS module is okay but no spark advance is present. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test. If DC voltage is not 5-7 volts, proceed to next step.
  4. Check For SAW Short In EDIS Module - Isolate EDIS Module  With ignition off and ECA connected, set DVOM on 20-volt DC scale. Push EDIS diagnostic cable SAW button at EDIS diagnostic cable connector to BOB. Start engine and measure voltage between SAW DETECTOR (21) and BAT- (7) at BOB. If DC voltage reading is 5-7 volts, replace EDIS module. SAW circuit is shorted in EDIS module. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test. If DC voltage is not 5-7 volts, proceed to next step.
  5. Check For SAW Short To Ground In Harness  With ignition off, disconnect ECA. Disconnect EDIS module from EDIS diagnostic cable module tee. Leave EDIS diagnostic cable connected to vehicle harness connector. Disconnect HEGO connector. Set DVOM on 200-ohm scale. Measure resistance between SAW E (45) and BAT- (7) at BOB. If resistance is less or greater than 100 ohms, repair short circuit. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test. If resistance is 100 ohms or greater, reconnect HEGO sensor and go to next step.
  6. Check For SAW Short To VBAT In Harness  With ignition off, and ECA disconnected, set DVOM on 20-volt DC scale. With KOEO, measure voltage between SAW E (45) and BAT- (7) at BOB. If DC voltage reading is less than .5 volt, repair short circuit. SAW is shorted to VBAT. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test. If voltage is .5 volt or greater, go to next step.
  7. Check For SAW Open  With ignition off and ECA disconnected, connect ECA BOB to ECA harness connector. Set DVOM on 200-ohm scale. Measure resistance between SAW E (45) at BOB and terminal No. 36 at ECA BOB. If resistance is less than 5 ohms, replace ECA. SAW is not being transmitted by ECA. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test. If resistance is not as specified, repair open circuit. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test.
  8. Inspect VR Sensor/Trigger Wheel  If VR sensor or trigger wheel is damaged, loose or misaligned, replace or repair components as required. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test. If trigger wheel and VR sensor are not damaged or loose, replace EDIS module. Module cannot control timing. Remove test equipment and reconnect all components. Clear Continuous Memory Codes and rerun Quick Test.
CAUTION: Never connect ECA to ECA BOB when performing EDIS diagnostics unless directed to do so.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.