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Diagnostic Aids

Perform this test when instructed during QUICK TEST  or if directed by other test procedures. This test is used to diagnose the following:

Fig 1: OBD-II Data Link Connector Terminals & Test Pin
G95E35844
Fig 2: Diagnostic Connector Terminals & Test Pins
G95F35845
TEST DIRECTORY

Fault Action
OBD-II Communication Error (1) Go To Step 1)
No PCM Data Through Diagnostic Connector Go To Step 10)
No TCM Data Through Diagnostic Connector Go To Step 20)
DTC P0600 Or P1605 Go To Step 30)
No DTCs Retrieved Manually (2) Go To Step 40)
(1) Diagnostic Data Link functional on scan tool.
(2) No DTCs retrieved using diagnostic harness connector.
  1. Step 1) Verify Retrieval Procedure  Turn ignition off. Inspect DLC and scan tool connector terminals. Repair as necessary. Verify that the correct procedures were used to retrieve trouble codes. See QUICK TEST . If no fault can be found in code retrieval procedure and data cables are okay, go to next step.
  2. Step 2) Check For VREF At TP Sensor  Turn ignition off. Disconnect Throttle Position (TP) sensor harness connector. Turn ignition on. Measure voltage between Brown wire (VREF) and Black/Yellow wire (SIG RTN). If voltage is 4-6 volts, VREF is okay, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.
  3. Step 3) Check Ground At OBD-II DLC  Turn ignition off. Inspect OBD-II DLC for damage. Measure resistance between pin No. 4 (ground) at OBD-II DLC and chassis ground on engine block. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open ground circuit. Repeat QUICK TEST .
  4. Step 4) Check Power At OBD-II DLC  Turn ignition off. Measure voltage between pin No. 16 and pin No. 4 at OBD-II DLC. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair open B+ circuit. Repeat QUICK TEST .
  5. Step 5) Check Ground At OBD-II DLC  Turn ignition off. Install breakout box (leave PCM disconnected). Measure resistance between pin No. 5 at OBD-II DLC and breakout box test pin GND. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open GND circuit. Repeat QUICK TEST .
  6. Step 6) Check ISO Circuit Continuity  Turn ignition off. Install breakout box (leave PCM disconnected). Measure resistance between pin No. 7 at OBD-II DLC and breakout box test pin No. 20 (ISO). If resistance less than 5 ohms, go to next step. If resistance greater than 5 ohms, repair open ISO circuit (Yellow/Green wire). Remove breakout box and repeat QUICK TEST .
  7. Step 7) Check ISO Circuit For Short To Ground  Turn ignition off. Install breakout box (leave PCM disconnected). Measure resistance between pin No. 7 at OBD-II DLC and ground. If resistance is greater than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair shorted ISO circuit (Green/Yellow wire). Remove breakout box and repeat QUICK TEST .
  8. Step 8) Check ISO Circuit For Short To Power  Disconnect negative battery cable. Install breakout box (leave PCM disconnected). Measure resistance between breakout box test pin No. 20 (ISO) and test pin No. 81 (VPWR) and test pin No. 67 (KAPWR). If resistance is greater than 10,000 ohms, replace PCM. Remove breakout box and repeat QUICK TEST . If resistance is less than 10,000 ohms, repair short to voltage in ISO circuit. Remove breakout box and repeat QUICK TEST.
    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. Step 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. Step 11) Check Power To Diagnostic Connector  Turn ignition on. Measure voltage between ground and pin No. 7 at diagnostic connector. If battery voltage exists, go to next step. If less than battery voltage exists, repair Blue wire between interior fuse panel and diagnostic connector.
  11. Step 12) Check Circuits Between PCM & Diagnostic Connector  Turn ignition off. Disconnect PCM and inspect connector for damage. Install breakout box (leave PCM disconnected). Verify continuity between breakout box test pins and diagnostic connector terminals as specified in DATA CIRCUIT TESTING NO. 1 table. Also verify circuits do not have continuity to ground.
    DATA CIRCUIT TESTING NO. 1

    Breakout Box Pin No. Diagnostic Connector Terminal No.
    62 1
    62 2
    65 9

    If resistance measurements indicate open or shorted circuit, repair circuit in question. If resistance measurements are as specified, replace PCM. Restore all electrical connections and repeat QUICK TEST .

    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. Step 20) Check Power To Diagnostic Connector  Turn ignition on. Measure voltage between ground and pin No. 7 at diagnostic connector. If battery voltage exists, go to next step. If less than battery voltage exists, repair Blue wire between interior fuse panel and diagnostic connector.
  13. Step 21) Check Circuits Between TCM & Diagnostic Connector  Turn ignition off. Disconnect TCM and inspect connector for damage. Install 60-pin breakout box (leave TCM disconnected). Verify continuity between breakout box test pins and diagnostic connector terminals as specified in DATA CIRCUIT TESTING NO. 2 table. Also verify circuits do not have continuity to ground.
    DATA CIRCUIT TESTING NO. 2

    Breakout Box Pin No. Diagnostic Connector Terminal No.
    45 1
    32 2
    48 9

    If resistance measurements indicate open or shorted circuit, repair circuit in question. If resistance measurements are as specified, replace PCM. Restore all electrical connections and repeat QUICK TEST .

  14. Step 22) Check Power & Ground To TCM  Install 60-pin breakout box (leave TCM disconnected). Measure voltage between power test pins No. 51, 57, 67 and 81; and ground test pins No. 39, 40, 46, 49 and 60. If battery voltage exists at all test pin power/ground combination, replace PCM. If any circuits are open, go to CIRCUIT TEST B.
    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. Step 30) Check Data Circuits Between PCM & TCM  Turn ignition off. Install 60-pin breakout box to TCM connector (leave TCM disconnected). Install 104-pin breakout box to PCM connector (leave PCM disconnected). Measure resistance between TCM breakout box tests and PCM breakout box test pins as specified in DATA CIRCUIT TESTING NO. 3 table. Also verify circuits do not have continuity to ground.
    DATA CIRCUIT TESTING NO. 3

    PCM Test Pin No. TCM Test Pin No.
    7 34
    36 25
    104 36

    If resistance measurements indicate open or shorted circuit, repair circuit in question. If resistance measurements are as specified, replace TCM. If symptoms still exists, replace PCM. Restore all electrical connections and repeat QUICK TEST .

    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 30) to step 40). No test procedures have been omitted.
  16. Step 40) Check Power To In-Line Diagnostic Connector  Turn ignition on. Disconnect in-line diagnostic connector. Measure voltage on Blue wire at in-line diagnostic connector (male side). If battery voltage exists, go to next step. If less than battery voltage exists, check 10-amp METER fuse in interior fuse panel. Replace fuse if necessary. If fuse is okay, repair open Blue wire between interior fuse panel and diagnostic connector.
  17. Step 41) Check Continuity Of Blue/White Wire  Turn Ignition Off. Disconnect PCM and inspect connector for damage. Install breakout box leave PCM disconnected. Disconnect in-line diagnostic connector. Measure resistance between breakout box test pin No. 12 and Blue/White wire at in-line diagnostic connector (female side). If resistance less than 5 ohms, go to CIRCUIT TEST B, to verify PCM power supply. If results of CIRCUIT TEST B are positive (power to PCM okay), replace PCM.
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