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Test QA: Unable To Activate Self-Test/Communication Error, Unable To Retrieve DTCS: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) Verify Self-Test Activation Method
    This test step addresses the following conditions:
    • Unable to retrieve DTCs.
    • Scan tool communication problem.
    • DTC displayed by scan tool is not listed.

    Turn ignition off. Disconnect scan tool from DLC. Inspect DLC and scan tool connector terminals. Repair as necessary. Ensure correct procedures were used to retrieve DTCs. See QUICK TEST . If no fault can be found in DTC retrieval procedure and data cables are okay, go to next step.

  2. 2) Check For VREF At TP Sensor

    Turn ignition off. Disconnect Throttle Position (TP) sensor harness connector. Turn ignition on. Using DVOM, measure voltage between VREF and SIG RTN circuits at TP sensor harness connector. See Figure. If voltage is 4.5-5.5 volts, VREF is okay. Reconnect TP sensor and go to next step. If voltage is less than 4.5 volts, go to TEST C  , step  2). If voltage is more than 5.5 volts, repair short to voltage on affected circuit. See WIRING DIAGRAMS article.

  3. 3) Check Chassis Ground At DLC

    Turn ignition off. Inspect OBD-II DLC for damage. See Figure. Using DVOM, measure resistance between DLC terminal No. 4 (ground) and chassis ground on engine block. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit.

  4. 4) Check B+ Circuit At DLC

    Turn ignition on. Using DVOM, measure voltage between DLC terminals No. 16 (B+) and No. 4 (GND). See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in B+ circuit. See WIRING DIAGRAMS article.

  5. 5) Check PWR GND At DLC

    Turn ignition off. Using DVOM, measure resistance between chassis ground and DLC terminal No. 5 (PWR GND). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in PWR GND circuit.

  6. 6) Check ISO Circuit Continuity

    Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance of ISO circuit (Yellow/Green wire) between DLC terminal No. 7 and PCM harness connector terminal No. 68. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ISO circuit. See WIRING DIAGRAMS article.

  7. 7) Check ISO Circuit For Short To Ground

    Using DVOM, measure resistance between DLC terminal No. 7 and chassis ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in ISO circuit.

  8. 8) Check ISO Circuit For Short To Power

    Using DVOM, measure resistance between terminal No. 68 (ISO circuit) and KAPWR, and VPWR circuits at PCM harness connector. See PCM TERMINAL CIRCUIT IDENTIFICATION  table. See Figure and Figure . If resistance is more than 10 k/ohms, replace PCM. If resistance is 10 k/ohms or less, repair short to power in ISO circuit. See WIRING DIAGRAMS article.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 10). No test procedures have been omitted.
    9. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  9. 10) Check OBD-II Communication
    Retrieve DTCs using generic function of scan tool. If scan tool communicates properly with PCM, go to next step. If scan tool does not communicate properly with PCM, go to step  1).

  10. 11) Check IGN START/RUN Circuit To DLC

    Turn ignition on. Using DVOM, measure voltage between chassis ground and DLC terminal No. 8 (Blue wire). See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in IGN START/RUN circuit.

  11. 12) Check Data Circuits Between PCM & DLC

    Turn ignition off. Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance between specified PCM harness connector terminals and DLC terminals, and chassis ground. See PCM-TO-DLC DATA CIRCUIT CHECK  table. See Figure and Figure . If all resistances are less than 5 ohms between DLC and PCM terminals, and more than 10 k/ohms between chassis ground and PCM terminals, replace PCM. If any resistance is 5 ohms or more between DLC and PCM terminals, and 10 k/ohms or less between chassis ground and PCM terminals, repair open or short to ground in affected circuit(s). See WIRING DIAGRAMS article.
    PCM-TO-DLC DATA CIRCUIT CHECK

    PCM Terminal No. Wire Color DLC Terminal No.
    17 Blue/White 1
    74 Yellow/Red 13
    75 Yellow/Black 12
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
    12. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  12. 20) Check IGN START/RUN Circuit To DLC
    Turn ignition on. Using DVOM, measure voltage between chassis ground and DLC terminal No. 8 (Blue wire). See Figure. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in IGN START/RUN circuit. See WIRING DIAGRAMS article.

  13. 21) Check Data Circuits Between TCM & DLC

    Turn ignition off. Disconnect TCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance between specified TCM harness connector terminals and DLC terminals, and chassis ground. See TCM-TO-DLC DATA CIRCUIT CHECK  table. See Figure and Figure . If all resistances are less than 5 ohms between DLC and TCM terminals, and more than 10 k/ohms between chassis ground and TCM terminals, go to next step. If any resistance is 5 ohms or more between DLC and TCM terminals, and 10 k/ohms or less between chassis ground and TCM terminals, repair open or short to ground in affected circuit(s). See WIRING DIAGRAMS article.
    TCM-TO-DLC DATA CIRCUIT CHECK

    TCM Terminal No. Wire Color DLC Terminal No.
    6 Yellow/Red 13
    7 Yellow/Black 12

  14. 22) Check Power & Ground Circuits To TCM

    Turn ignition on. Using DVOM, measure voltage between VPWR and KAPWR and GND circuits at TCM harness connector. See TCM CIRCUIT TERMINAL IDENTIFICATION  table. If voltages between all PWR and GND circuits are more than 10 volts, replace TCM. If voltages between any PWR and GND circuits are 10 volts or less, go to TEST B  , step  1).
    TCM CIRCUIT TERMINAL IDENTIFICATION

    Circuit TCM Connector (Terminal No.) Wire Color
    GND C277b (1 & 24) Black/Red
    KAPWR C277b (4) Purple
    VPWR C277a (10 & 19) Light Green
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 30). No test procedures have been omitted.
    15. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  15. 30) DTC P0600 Or P1605: Check Data Circuits Between PCM & TCM
    Turn ignition off. Disconnect PCM and TCM harness connectors. Inspect connectors for damaged pins and repair if necessary. Using DVOM, measure resistance of COMM circuits between TCM and PCM connectors. Using DVOM, measure resistance between COMM and GND circuits at PCM and TCM connectors. See PCM-TO-TCM COMM CIRCUIT IDENTIFICATION  tables. If all resistances are less than 5 ohms between PCM and TCM, and more than 10 k/ohms between COMM circuits and GND at PCM and TCM, replace TCM. If communication error still exists, reinstall original TCM and replace PCM. If any resistance is 5 ohms or more between PCM and TCM, or 10 k/ohms or less between COMM circuits and GND at PCM and/or TCM, repair open or short to ground in affected circuits. See WIRING DIAGRAMS article.
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