Test D: Powertrain Control Module (Pcm) Does Not Respond To NGS Tester
NOTE:
If test results indicate PCM is faulty, always check for any engine performance related Diagnostic Trouble Codes (DTCs) prior to replacing PCM. If any DTCs are present, service DTCs as necessary and retest. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
NOTE:
Depending on module configuration, with all modules connected and with ignition switch in RUN position or with engine running 2-3 volts may be present at Data Link Connector (DLC) terminals No. 2 (White/Blue wire) and No. 10 (Black/Blue wire). These are the Standard Corporate Protocol (SCP) diagnostic communications network circuits.
- Turn ignition on. Perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM. If NGS tester indicates PCM: NO RESPONSE ON CKT 914 (BUS +), go to next step. If NGS tester does not indicate PCM: NO RESPONSE ON CKT 914 (BUS +), go to step 7 .
- Turn ignition off. Disconnect NGS tester. Disconnect PCM connector located under center console. See Figure . Inspect connector for loose, damaged or corroded terminals. Pay particular attention to terminal No. 16. Repair connector as necessary and retest system for normal operation. If connector is okay, inspect Data Link Connector (DLC) for loose, damaged or corroded terminals. Pay particular attention to terminal No. 2 (White/Blue wire). Repair connector as necessary and retest system for normal operation. If connector is okay, go to next step.
- Using an ohmmeter, measure resistance of White/Blue wire between terminal No. 16 at PCM connector and terminal No. 2 at DLC. See Figure and Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, go to step 7 .
- Turn ignition on. Using a voltmeter, measure voltage between terminals No. 2 (White/Blue wire) and No. 16 (Green wire) at DLC. Also, measure voltage between terminals No. 2 (White/Blue wire) and No. 4 (Black wire) at DLC. See Figure . If voltage is indicated at any terminal, go to next step. If voltage is not indicated at any terminal, replace PCM and retest system for normal operation.
- Turn ignition off. Disconnect White 10-pin in-line connector C256 located near PCM. See Figure . Turn ignition on. Using a voltmeter, measure voltage between terminals No. 2 (White/Blue wire) and No. 16 (Green wire) at DLC. Also, measure voltage between terminals No. 2 (White/Blue wire) and No. 4 (Black wire) at DLC. See Figure . If voltage is indicated at any terminal, repair White/Blue wire between in-line connector C256 and DLC. Retest system for normal operation. If voltage is not indicated at any terminal, repair White/Blue wire between in-line connector C256 and PCM. Retest system for normal operation.
- Turn ignition off. Disconnect White 10-pin in-line connector C256 located near PCM. See Figure . Using an ohmmeter, measure resistance of White/Blue wire between terminal No. 6 at female half of in-line connector C256 and terminal No. 2 at DLC. See Figure and Fig 2 . If resistance is less than 5 ohms, repair open in White/Blue wire between in-line connector C256 and PCM. Retest system for normal operation. If resistance is 5 ohms or more, repair open in White/Blue wire between in-line connector C256 and DLC. Retest system for normal operation.
- Disconnect NGS tester. Disconnect PCM connector located under center console. See Figure . Inspect connector for loose, damaged or corroded terminals. Pay particular attention to terminal No. 10. Repair connector as necessary and retest system for normal operation. If connector is okay, go to next step.
- Using an ohmmeter, measure resistance of Black/Blue wire between terminal No. 15 at PCM connector and terminal No. 10 at DLC. See Figure and Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, go to step 11 .
- Turn ignition on. Using a voltmeter, measure voltage between terminals No. 10 (Black/Blue wire) and No. 16 (Green wire) at DLC. Also, measure voltage between terminals No. 10 (Black/Blue wire) and No. 4 (Black wire) at DLC. See Figure . If voltage is indicated at any terminals, go to next step. If voltage is not indicated at any terminals, go to appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
- Turn ignition off. Disconnect White 10-pin in-line connector C256 located near PCM. See Figure . Turn ignition on. Using a voltmeter, measure voltage between terminals No. 10 (Black/Blue wire) and No. 16 (Green wire) at DLC. Also, measure voltage between terminals No. 10 (Black/Blue wire) and No. 4 (Black wire) at DLC. See Figure . If voltage is indicated at any terminal, repair Black/Blue wire between in-line connector C256 and DLC. Retest system for normal operation. If voltage is not indicated at any terminal, repair Black/Blue wire between in-line connector C256 and PCM. Retest system for normal operation.
- Turn ignition off. Disconnect White 10-pin in-line connector C256 located near PCM. See Figure . Using an ohmmeter, measure resistance of Black/Blue wire between terminal No. 10 at DLC and terminal No. 1 at female half of in-line connector C256. See Figure and Fig 2 . If resistance is less than 5 ohms, repair open in Black/Blue wire between in-line connector C256 and PCM. Retest system for normal operation. If resistance is 5 ohms or more, repair open in Black/Blue wire between in-line connector C256 and DLC. Retest system for normal operation.