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Diagnostic Aids

Perform this test when directed by QUICK TEST . This CIRCUIT TEST is intended to diagnose the following:

Fig 1: Fuel Rail Components
G95I35939
Fig 2: Injection Pressure (IP) Sensor Test Circuits & Connector Terminals
G95B35940
Fig 3: Fuel Rail Solenoid Connector Terminals
G95C35941
IP SENSOR VOLTAGE-TO-FUEL PRESSURE CONVERSION CHART

Voltage (DC) Pressure (psi)
4.5 150
4.1 140
3.7 130
3.3 120
2.9 110
2.5 100
2.1 90
1.7 80
1.3 70
0.9 60
0.5 50
0.1 40
0.0 37.5
  1. Step 1) KOEO/KOER DTC P0192  DTC P0192 indicates IP voltage signal is less than self-test minimum. Possible causes for this fault are:
    • IP signal is shorted to SIG RTN or PWR GND.
    • IP circuit is open.
    • Low fuel pressure.
    • Faulty IP sensor.
    • Faulty PCM.

    Ensure vehicle has fuel. With scan tester connected to DLC, turn ignition on. Using scan tester, access IP PID. If IP PID voltage is less than 0.2 volt, go to next step. If IP PID voltage is 0.2 volt or more, go to step 10).

  2. Step 2) Turn ignition off. Disconnect IP wiring harness connector. Using jumper wire, connect IP terminal to VREF terminal. If scan tester communication problem is present, go to step 8). Using scan tester, access IP PID. If IP PID voltage is less than 4.5 volts, go to next step. If IP PID voltage is 4.5 volts or more, replace IP sensor and repeat QUICK TEST .
  3. Step 3) Measure VREF Voltage  With IP sensor disconnected, turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at IP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to CIRCUIT TEST C.
  4. Step 4) Check IP Circuit Continuity  Turn ignition off. Leave IP sensor disconnected. Disconnect PCM 104-pin connector and inspect for damage. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between IP terminal of IP sensor wiring harness connector and test pin No. 63 (IP) at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit and repeat QUICK TEST .
  5. Step 5) Check IP Circuit For Short To PWR GND Or SIG RTN  Leave ignition off and IP sensor disconnected. Measure resistance between test pin No. 63 (IP) and test pins No. 91 (SIG RTN), 24 and 103 (PWR GND) at breakout box. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST .
  6. Step 6) KOEO/KOER DTC P0193  DTC P0193 indicates IP voltage signal is greater than self-test maximum. Possible causes for this fault are:
    • IP signal is shorted to VREF or PWR.
    • VREF circuit shorted to PWR.
    • High fuel pressure.
    • Faulty IP sensor.
    • Faulty PCM.

    Turn ignition off. Release fuel pressure. Connect pressure gauge to schrader valve. With scan tester connected to DLC, turn ignition on. Using scan tester, access IP sensor pressure PID. If PID pressure is 140 psi or less, go to next step.

  7. Step 7) KOEO/KOER DTC P0193  Possible causes for this fault are:
    • IP signal is shorted to VREF or PWR.
    • VREF circuit shorted to PWR.
    • Faulty IP sensor.
    • Faulty PCM.

    Turn ignition off. Disconnect IP sensor wiring harness connector. With scan tester connected to DLC, turn ignition on. Using scan tester, access IP PID. If IP PID voltage is less than 0.2 volt, replace IP sensor. If Continuous Memory DTC P0193 is present, go to step 10). If IP PID voltage is 0.2 volt or more, go to next step.

  8. Step 8) Measure VREF Voltage  With IP sensor disconnected, turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at IP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to CIRCUIT TEST C.
  9. Step 9) Check IP Circuit For Short To PWR GND Or SIG RTN  Leave ignition off and IP sensor disconnected. Disconnect PCM 104-pin connector and inspect for damage. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 63 (IP) and test pins No. 91 (SIG RTN), 24 and 103 (PWR GND) at breakout box. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST .
  10. Step 10) Check For Intermittent Fault  Leave IP sensor wiring harness connector disconnected. With scan tester connected to DLC, turn ignition on. Using scan tester, access IP PID. Observe PID voltage for fault while tapping on IP sensor. Wiggle and bend wiring harness and connector between sensor and PCM. Fault will be indicated by a sudden change in PID voltage. If fault is indicated, isolate and repair as necessary. If fault is not indicated, symptom is intermittent and cannot be located at this time. Go to CIRCUIT TEST Z for additional test procedure.
  11. Step 11) KOEO/KOER DTC P0191  DTC P0193 indicates IP voltage signal is greater than self-test maximum. Possible causes for this fault are:
    • High fuel pressure.
    • Low fuel pressure.
    • Excessive resistance in circuit.
    • Faulty IP sensor.
    • Low or no fuel.

    Ensure vehicle has fuel. With scan tester connected to DLC, turn ignition on. Turn ignition off. Release fuel pressure. Connect pressure gauge to schrader valve. Turn ignition on. Check fuel pressure. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is within specification, go to next step.

  12. Step 12) Check IP PID Fuel Pressure  With scan tester connected to DLC, turn ignition on. Using scan tester, access IP PID. If IP PID psi reading is within 10 psi of fuel pressure gauge psi reading, go to next step. If IP PID psi reading is not as specified, repeat QUICK TEST .
  13. Step 13) Check Fuel Rail Solenoid  Ensure scan tester is connected to DLC and ignition turned on. Using scan tester, access OUTPUT TEST MODE. While observing fuel rail solenoid, cycle output on and off several times. If solenoid clicking can be heard or felt, go to next step. In no solenoid response is observed, go to step 17).
  14. Step 14) Measure VREF Voltage  With IP sensor disconnected, turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at IP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to CIRCUIT TEST C.

    Step 1Check IP Circuit For Excessive Resistance  Turn ignition on. Disconnect IP sensor. Disconnect PCM 104-pin connector and inspect for damage. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between IP terminal of IP sensor wiring harness connector and test pin No. 63 (IP) at breakout box. Measure resistance between SIG RTN terminal of IP sensor wiring harness connector and test pin No. 91 (SIG RTN) at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair circuit and repeat QUICK TEST .

  15. Step 16) Monitor IP Circuit With Scan Tester  Turn ignition off. Disconnect IP sensor wiring harness connector. With scan tester connected to DLC, turn ignition on. Using scan tester, access IP PID. If IP PID voltage is less than 0.2 volt, replace IP sensor. If IP PID voltage is 0.2 volt or more, replace PCM and repeat QUICK TEST .
  16. Step 17) Check Voltage At Fuel Rail Solenoid  Ensure scan tester is connected to DLC and ignition turned on. Using scan tester, access OUTPUT TEST MODE and select ALL ON. Disconnect fuel rail solenoid wiring harness connector. Measure voltage between PWR circuit terminal and battery negative terminal. If voltage is 10.5 volts or more, replace solenoid and repeat QUICK TEST. If voltage is less than 10.5 volts, repair open in PWR circuit and repeat QUICK TEST .
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