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Test H: No Module/Network Communications - ISO 9141 Link

WARNING: This page is about a different car, the 2001 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Depending on module configuration, with all modules connected and with ignition switch in RUN position or with engine running, 2-3 volts should be present at Data Link Connector (DLC) terminal No. 7 (Light Blue/White wire). This is the International Standards Organization (ISO) 9141 diagnostic communications network circuit.
  1. Turn ignition switch to LOCK position. Inspect Data Link Connector (DLC) for harness connector for loose, damaged or corroded terminals. DLC is located below driver's side instrument cluster, right of steering wheel. If harness connector is okay, go to next step. If harness connector is damaged, repair as necessary.
  2. Disconnect Generic Electronic Module (GEM)/Central Timer Module (CTM) 26-pin harness connector C239. GEM/CTM is located below driver's side of instrument panel, left of steering column. See Figure. Measure resistance in Light Blue/White wire between GEM/CTM harness connector C239 terminal No. 25 and DLC terminal No. 7. See Figure and Figure . If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Light Blue/White wire between GEM/CTM harness connector C239 and DLC. See WIRING DIAGRAMS .
  3. Turn ignition switch to RUN position. Perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST . If NGS tester does not indicate system PASSED, go to next step. If NGS tester indicates system PASSED, go to step  14.
  4. Turn ignition switch to LOCK position. Connect GEM/CTM harness connector C239. Disconnect Remote Anti-theft Personality (RAP)/Central Security Module (CSM) harness connector C256. Measure resistance in Light Blue/White wire between RAP/CSM harness connector terminal No. 3 and DLC terminal No. 7. If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step  7.
  5. Disconnect Gray in-line harness connector C247. Harness connector C247 is located behind left side of instrument panel. Inspect harness connector for loose, damaged or corroded terminals. If harness connector is okay, go to next step. If harness connector is damaged, repair as necessary.
  6. Measure resistance in Light Blue/White wire between Gray in-line harness connector C247 (female side) terminal No 16 and DLC terminal No. 7. If resistance is more than 5 ohms, repair open or short in Light Blue/White wire between Gray in-line harness connector C247 (female side) and DLC. If resistance is 5 ohms or less, repair open or short in Light Blue/White wire between Gray in-line harness connector C247 (male side) and DLC.
  7. Turn ignition switch to RUN position. Perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST . If NGS tester does not indicate system PASSED, go to next step. If NGS tester indicates system PASSED, go to step  15.
  8. Turn ignition switch to LOCK position. Connect RAP/CSM harness connector C256. Deactivate air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article. Disconnect Restraint Control Module (RCM) harness connector C208. Measure resistance in Light Blue/White wire between RCM harness connector C208 terminal No 5 and DLC terminal No 7. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Light Blue/White wire between RCM and DLC. See WIRING DIAGRAMS .
  9. Turn ignition switch to RUN position. Perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST . If NGS tester does not indicate system PASSED, go to next step. If NGS tester indicates system PASSED, go to step  16
  10. Turn ignition switch to LOCK position. Connect RCM harness connector C208. Disconnect 4-Wheel Anti-Lock Brake System (4WABS) control module harness connector C146. Measure resistance in Light Blue/White wire between 4WABS control module harness connector C146 terminal No. 1 and DLC terminal No 7. If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step  13.
  11. Disconnect Gray in-line harness connector C160. Harness connector C247 is located in left rear of engine compartment. Inspect harness connector for loose, damaged or corroded terminals. If harness connector is okay, go to next step. If harness connector is damaged, repair as necessary.
  12. Measure resistance in Light Blue/White wire between Gray in-line harness connector C160 (male side) terminal No. 29 and DLC terminal No. 7. If resistance is more than 5 ohms, repair open or short in Light Blue/White wire between Gray in-line harness connector C160 (female side) and DLC. If resistance is 5 ohms or less, repair open or short in Light Blue/White wire between Gray in-line harness connector C160 (male side) and DLC.
  13. Turn ignition switch to RUN position. Perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST . If NGS tester does not indicate system PASSED, go to next step. If NGS tester indicates system PASSED, go to step  17
  14. Disconnect all GEM/CTM harness connectors. Check GEM/CTM harness connectors for loose, pushed out or corroded terminals. Connect all disconnected connectors and retest system. If problem still exists, replace GEM/CTM and perform data link test. See DATA LINK DIAGNOSTIC TEST . If problem does not exist, system is operating normally. Clear all diagnostic trouble codes and perform self test.
  15. Disconnect all RAP/CSM harness connectors. Check RAP/CSM harness connectors for loose, pushed out or corroded terminals. Connect all disconnected RAP/CSM harness connectors and retest system. If problem still exists, replace RAP/CSM and perform data link test. See DATA LINK DIAGNOSTIC TEST . If problem does not exist, system is operating normally. Clear all diagnostic trouble codes and perform self test.
  16. Disconnect all RCM harness connectors. Check RCM harness connectors for loose, pushed out or corroded terminals. Connect all disconnected connectors and retest system. If problem still exists, replace RCM and perform data link test. See DATA LINK DIAGNOSTIC TEST . If problem does not exist, system is operating normally. Clear all diagnostic trouble codes and perform self test.
  17. Disconnect all 4WABS harness connectors. Check 4WABS harness connectors for loose, pushed out or corroded terminals. Connect all disconnected 4WABS harness connectors and retest system. If problem still exists, replace 4WABS and perform data link test. See DATA LINK DIAGNOSTIC TEST . If problem does not exist, system is operating normally. Clear all diagnostic trouble codes and perform self test.
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