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Home >> Ford >> 1988 >> Bronco II 4WD, Standard, M5OD-R1 >> Repair and Diagnosis >> Engine Performance >> System >> EEC-IV CEC System >> Quick Test >> Test A1 - No Start Test
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Test A1 - No Start Test

Fig 1: TFI Module Circuits
G11071

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: fuel quantity and quality, ignition system damage, cracks, moisture, etc., engine mechanical conditions such as bad valves, timing belt, etc. Also included are starter and battery circuit problems.

  1. Starting System  - Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, but does not start or stalls after starting, go to next step.
  2. Checking VREF Signal At TPS  - Turn key off and wait 10 seconds. Set DVOM on 20-volt scale and disconnect Throttle Position (TP) sensor. Turn key on, leaving engine off (KOEO). Measure voltage at TPS harness connector between Voltage Reference (VREF) and signal return. If reading is less than 4 volts or more than 6 volts, go to TEST A3  , step 1). If reading is between 4 and 6 volts, reconnect TPS and go to next step.
  3. Checking For Spark  - Disconnect any spark plug wire and connect spark tester between plug wire and engine ground. Crank engine and check for spark. If spark exists, connect spark plug wire and go to step 13). If there is no spark, connect spark plug wire and go to next step.
  4. Checking For Spark At Coil  - Remove high tension coil wire from distributor and install spark tester. Check for spark while cranking engine. If spark exists, connect coil wire and service or repair TFI ignition system. If there is no spark, connect coil wire and go to next step.
  5. Ignition Ground Continuity  - Turn key off and wait 10 seconds. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale and disconnect TFI. Measure resistance between Test Pin No. 16 and TFI harness connector ignition ground. If reading is more than 5 ohms, repair harness and repeat QUICK TEST  . If reading is less than 5 ohms, go to next step.
  6. SPOUT Circuit Isolation  - With breakout box installed and box timing switch on "DISTRIBUTOR" position, connect TFI and ECA. Try to start vehicle. If vehicle starts, go to step 10). If vehicle does not start, go to next step.
  7. Checking SPOUT Signal  - Move breakout box timing switch to "COMPUTED" position. Set DVOM on 20-volt scale and measure voltage between Test Pin No. 36 and chassis ground while cranking engine. If voltage is between 3 and 6 volts, EEC system is NOT at fault. TFI ignition system should be diagnosed. If voltage is less than 3 volts or more than 6 volts, go to next step.
  8. Checking SPOUT For Shorts  - Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA and TFI. Set DVOM on 200K-ohm scale and measure resistance between Test Pin No. 36 and Test Pins No. 16, 20, 26, 40, and 60 for short to ground. Measure resistance between Test Pin No. 36 and Test Pins No. 37 and 57 for short to power. Measure resistance between Test Pins No. 36 and 56 for short to PIP. If any reading is less than 10K ohms, repair short in harness and repeat QUICK TEST  . If engine still does not start, go to next step. If all readings are 10K ohms or more, go to next step.
  9. Isolating Shorts In Processor  - Turn key off and wait 10 seconds. With breakout box installed, connect ECA, but leave TFI disconnected. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 36 and Test Pins No. 37 and 57 for short to power. Measure resistance between Test Pin No. 36 and Test Pins No. 40 and 60 for short to ground. If any reading is less than 5 ohms, replace ECA and repeat QUICK TEST  . If all readings are 5 ohms or more, connect TFI and go to next step.
  10. Checking PIP Signal  - With breakout box installed and DVOM on 20-volt scale, measure voltage between Test Pins No. 56 and 16, while cranking engine. If reading is between 3 and 6 volts, remove breakout box. Replace ECA and repeat QUICK TEST  . If reading is less than 3 volts or more than 6 volts, go to next step.
  11. Continuity of PIP Circuit  - Install breakout box, turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect TFI and ECA. Measure resistance between Test Pin No. 56 and TFI connector PIP circuit. If reading is 5 ohms or more, repair open PIP circuit and repeat QUICK TEST  . If readings is less than 5 ohms, go to next step.
  12. Checking PIP Circuit For Shorts  - With breakout box installed and ECA disconnected, turn key off. Disconnect TFI connector and set DVOM on 200K-ohm scale. Measure resistance between Test Pin No. 56 and Test Pins No. 16, 20, 26, 40, and 60 for short to ground. Measure resistance between Test Pin No. 56 and Test Pins No. 37 and 57 for short to power. Measure resistance between Test Pin No. 56 and Test Pin No. 36 for short to Spark Output (SPOUT). If any reading is less than 10K ohms, repair PIP circuit and repeat QUICK TEST  . If all readings are more than 10K ohms, repair TFI ignition system.
  13. Verifying SPOUT Signal  - Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector and inspect for damaged pins, corrosion, or loose wires. Repair as necessary. Install breakout box and connect ECA. Ensure breakout box timing switch is in "COMPUTED" position. Set DVOM on 20-volt scale and measure voltage between Test Pin No. 36 and chassis ground while cranking engine. If reading is between 3 and 6 volts, go to next step; except vehicles with Mass Air (MA) system, which go to step 16). If reading is less than 3 volts or more than 6 volts, go to step 10).
  14. Fuel Pump Check  - Connect pressure gauge to vehicle. Note initial pressure reading, then pressurize fuel system by turning key on for one second, turning key off, and then waiting 10 seconds. Repeat on, off, and wait sequence 5 times. Turn key off and wait 10 seconds. If pressure increased, go to TEST D20  , step 1) for MPFI fuel injected engines. If pressure increased, go to TEST D20, step 2) for CFI fuel injected engines. If pressure did not increase, go to next step.
  15. Inertia Switch Check  - Turn ignition key off and install fuel pressure gauge. Locate fuel pump inertia switch. Inspect inertia switch reset button. If inertial switch is not in the DOWN (ON) position, reset switch. If engine still will not start, go to step 14). If inertia switch is in the DOWN (ON) position, go to TEST C2  , FUEL PUMP CIRCUIT (INERTIA SWITCH).
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