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Test L: No Module/Network Communications - ISO 9141 Network

WARNING: This page is about a different car, the 2002 Lincoln Navigator, 2002 Ford Expedition, 2001 Lincoln Navigator, and 2001 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: To avoid accidental deployment and possible personal injury, backup power supply must be depleted before repairing or replacing any air bag restraint system components. Disconnect negative battery cable and, if equipped, auxiliary power supplies. Wait one minute for backup power supply energy to deplete.
CAUTION: Disconnect battery before disconnecting GEM connectors. Failure to do so will result in GEM storing erroneous codes and may also result in erratic operation after connection of GEM.
NOTE: After making any repair, perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM.
  1. Turn ignition switch to LOCK position. Inspect Data Link Connector (DLC) for loose, damaged or corroded terminals. Pay particular attention to terminals No. 4 (Black wire) and No. 7 (Light Blue/White wire). See Figure. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
  2. Disconnect negative battery cable. Disconnect Generic Electronic Module (GEM) Gray 26-pin harness connector C239. GEM is located on back side of central junction box. Inspect GEM harness connector C239 for loose, damaged or corroded terminals. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
  3. Measure resistance in Light Blue/White wire between GEM 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 and DLC.
  4. Connect battery cable. Turn ignition switch to RUN position. Ensure GEM is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, go to next step. If NGS tester indicates SYSTEM PASSED, replace GEM. See GENERIC ELECTRONIC MODULE  under REMOVAL & INSTALLATION.
  5. Turn ignition switch to LOCK position. Connect GEM harness connector. Disconnect central security module 26-pin harness connector C256. Central security module is located behind left side of instrument panel. Measure resistance in Light Blue/White wire between central security module 26-pin harness connector C256 terminal No. 3 and DLC terminal No. 7. See Figure and Figure . If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step  7.
  6. Disconnect in-line Gray 16-pin harness connector C247. See Figure. Measure resistance in Light Blue/White wire between in-line harness connector C247 (female side) terminal No. 16 and DLC terminal No. 7. See Figure and Figure . If resistance is more than 5 ohms, repair open in Light Blue/White wire between DLC and in-line harness connector C247 (female side). If resistance is 5 ohms or less, repair open in Light Blue/White wire between central security module and in-line harness connector C247 (male side).
  7. Turn ignition switch to RUN position. Ensure central security module is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, go to next step. If NGS tester indicates SYSTEM PASSED, replace central security module. See CENTRAL SECURITY MODULE  under REMOVAL & INSTALLATION.
  8. Turn ignition switch to LOCK position. Disable air bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS. Disconnect Restraint Control Module (RCM) 26-pin harness connector C2005. RCM is located behind right side of instrument panel. Measure resistance in Light Blue/White wire between RCM harness connector C2005 terminal No. 5 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.
  9. Turn ignition switch to RUN position. Ensure RCM is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, go to next step. If NGS tester indicates SYSTEM PASSED, replace RCM. See RESTRAINT CONTROL MODULE  under REMOVAL & INSTALLATION.
  10. Turn ignition switch to LOCK position. Connect RCM harness connector. Disconnect 4-Wheel Anti-Lock Brake System (4WABS) control module 25-pin harness connector. 4WABS control module is located in left front of engine compartment. Measure resistance in Light Blue/White wire between 4WABS control module harness connector C146 terminal No. 1 and DLC terminal No. 7. See Figure and Figure . If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step  13.
  11. Disconnect in-line 40-pin harness connector C160. See Figure. Inspect in-line 40-pin harness connector C160 for loose, damaged or corroded terminals. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
  12. Measure resistance in Light Blue/White wire between 4WABS control module harness connector C146 terminal No. 1 and in-line harness connector C160 (male side) terminal No. 29. See Figure and Figure . If resistance is more than 5 ohms, repair open in Light Blue/White wire between 4WABS control module harness connector and in-line harness connector C160 (male side). If resistance is 5 ohms or less, repair open in Light Blue/White wire between in-line harness connector C160 (female side) and DLC.
  13. Turn ignition switch to RUN position. Connect in-line harness connector C160. Ensure 4WABS control module is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, go to next step. If NGS tester indicates SYSTEM PASSED, replace 4WABS control module. See 4-WHEEL ANTI-LOCK BRAKE SYSTEM CONTROL MODULE  under REMOVAL & INSTALLATION.
  14. Turn ignition switch to LOCK position. Connect 4WABS control module harness connector. Disconnect Driver's Seat Module (DSM) 22-pin harness connector C356. DSM is located under driver's seat. Measure resistance in Light Blue/White wire between DLC terminal No. 7 and DSM harness connector C356 terminal No. 22. See Figure and Figure . If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step  17.
  15. Disconnect in-line harness connector C201. See Figure. Inspect in-line harness connector C201 for loose, damaged or corroded terminals. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
  16. Measure resistance in Light Blue/White wire between harness connector C201 (female side) terminal No. 11 and DSM harness connector C356 terminal No. 22. See Figure and Figure . If resistance is more than 5 ohms, repair open in Light Blue/White wire between DSM and in-line harness connector C201 (female side). If resistance is 5 ohms or less, repair open in Light Blue/White wire between DLC and in-line harness connector C201 (male side).
  17. Connect in-line harness connector C201. Turn ignition switch to RUN position. Ensure DSM is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, go to next step. If NGS tester indicates SYSTEM PASSED, replace DSM. See DRIVER'S SEAT MODULE  under REMOVAL & INSTALLATION.
  18. Turn ignition switch to LOCK position. Connect DSM harness connector C356. Disconnect Parking Aid Module (PAM) harness connector C439. PAM is located under right rear interior trim panel. Measure resistance in Light Blue/White wire between PAM harness connector C439 terminal No. 5 and DLC terminal No. 7. See Figure and Figure . If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step  20.
  19. Disconnect in-line harness connector C201. See Figure. Measure resistance in Light Blue/White wire between harness connector C201 (female side) terminal No. 11 and PAM harness connector C439 terminal No. 5. See Figure and Figure . If resistance is more than 5 ohms, repair open in Light Blue/White wire between PAM and in-line harness connector C201 (female side). If resistance is 5 ohms or less, repair open in Light Blue/White wire between DLC and in-line harness connector C201 (male side).
  20. Turn ignition switch to RUN position. Ensure PAM is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, go to next step. If NGS tester indicates SYSTEM PASSED, replace PAM. See PARKING AID MODULE  under REMOVAL & INSTALLATION.
  21. Turn ignition switch to LOCK position. Connect PAM harness connector C439. Disconnect Air Suspension Control Module (ASCM) harness connector C296. ASCM is located behind radio in center of instrument panel. Measure resistance in Light Blue/White wire between ASCM harness connector C296 terminal No. 29 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.
  22. Turn ignition switch to RUN position. Ensure ASCM is still disconnected and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If NGS tester does not indicate SYSTEM PASSED, ensure all connectors are properly connected and retest system. If NGS tester indicates SYSTEM PASSED, replace ASCM. See AIR SUSPENSION CONTROL MODULE  under REMOVAL & INSTALLATION.
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