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Test D: Powertrain Control Module (Pcm) Does Not Respond To NGS Tester

NOTE: When performing the following test, the NGS tester may display BUS circuit No. 131 as circuit No. 914. 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 TESTS W/CODES article in the ENGINE PERFORMANCE section.
  1. Turn ignition on. Perform data link diagnostic procedure. See DATA LINK DIAGNOSTIC TEST under COMMUNICATION NETWORK DIAGNOSTICS. If NGS tester indicates PCM: NO RESPONSE ON CKT 131 (BUS +) (Escort ZX2 may display CKT131=00000001), go to next step. If NGS tester does not indicate PCM: NO RESPONSE ON CKT 131 (BUS +), go to step 7).
  2. 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 connector 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.
  3. 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 6).
  4. 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 terminals, go to next step. If voltage is not indicated at any terminals, replace PCM and retest system for normal operation.
  5. Turn ignition off. Disconnect White 10-pin 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 terminals, repair White/Blue wire between connector C256 and DLC. Retest system for normal operation. If voltage is not indicated at any terminals, repair White/Blue wire between connector C256 and PCM. Retest system for normal operation.
  6. Turn ignition off. Disconnect White 10-pin connector C256 located near PCM. See Figure . Using an ohmmeter, measure resistance of White/Blue wire between terminal No. 6 at female half of 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 connector C256 and PCM. Retest system for normal operation. If resistance is 5 ohms or more, repair open in White/Blue wire between connector C256 and DLC. Retest system for normal operation.
  7. 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.
  8. 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).
  9. 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 step 12).
  10. Turn ignition off. Disconnect White 10-pin 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 terminals, repair Black/Blue wire e between connector C256 and DLC. Retest system for normal operation. If voltage is not indicated at any terminal, repair Black/Blue wire between connector C256 and PCM. Retest system for normal operation.
  11. Turn ignition off. Disconnect White 10-pin 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 connector C256. See Figure and Fig 2 . If resistance is less than 5 ohms, repair open in Black/Blue wire between connector C256 and PCM. Retest system for normal operation. If resistance is 5 ohms or more, repair open in Black/Blue wire between connector C256 and DLC. Retest system for normal operation.
  12. Using an ohmmeter, measure resistance of Pink/Green wire between terminal No. 13 at PCM connector and terminal No. 13 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 15).
  13. Turn ignition on. Using a voltmeter, measure voltage between terminals No. 13 (Pink/Green wire) and No. 16 (Green wire) at DLC. Also, measure voltage between terminals No. 13 (Pink/Green 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, replace PCM and retest system for normal operation.
  14. Turn ignition off. Disconnect White 10-pin connector C256 located near PCM. See Figure . Turn ignition on. Using a voltmeter, measure voltage between terminals No. 13 (Pink/Green wire) and No. 16 (Green wire) at DLC. Also, measure voltage between terminals No. 13 (Pink/Green wire) and No. 4 (Black wire) at DLC. See Figure . If voltage is indicated at any terminals, repair Pink/Green whir e between connector C256 and DLC. Retest system for normal operation. If voltage is not indicated at any terminal, repair Pink/Green wire between connector C256 and PCM. Retest system for normal operation.
  15. Turn ignition off. Disconnect White 10-pin connector C256 located near PCM. See Figure . Using an ohmmeter, measure resistance of Pink/Green wire between terminal No. 13 at DLC and terminal No. 2 at female half of connector C256. See Figure and Fig 2 . If resistance is less than 5 ohms, repair open in Pink/Green wire between connector C256 and PCM. Retest system for normal operation. If resistance is 5 ohms or more, repair open in Pink/Green wire between connector C256 and DLC. Retest system for normal operation.
Fig 1: Identifying Powertrain Control Module (PCM) Terminals
G97E28807Courtesy of FORD MOTOR CO.
Fig 2: Identifying Connector C256 Terminals (Female Half Of Connector Shown)
G98F01709Courtesy of FORD MOTOR CO.
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