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

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 DLC terminal No. 7 (Light Blue/White wire). This is the ISO 9141 diagnostic communications network circuit.
  1. Turn ignition switch to LOCK position. Inspect Data Link Connector (DLC) for loose, damaged or corroded terminals. Repair connector as necessary. If DLC is okay, go to next step.
  2. Disconnect ABS module harness connector C135. Measure resistance of Light Blue/White wire between ABS module connector C135 terminal No. 1 and Data Link Connector (DLC) terminal No. 7. See Figure and Figure . If resistance is less than 5 ohms, go to step  4. If resistance is 5 ohms or more, go to next step.
  3. Disconnect in-line 40-pin connector C146. Inspect both halves of in-line 40-pin connector C146 for loose, damaged or corroded terminals. Repair connector as necessary. Measure resistance in Light Blue wire between in-line harness connector C146 (male side) terminal No. 5 and DLC terminal No. 7. See Figure and Figure . If resistance is less than 5 ohms, repair open in Light Blue/White wire between in-line harness connector C146 (female side) and ABS module. If resistance is greater than 5 ohms, repair open in Light Blue/White wire between DLC and in-line harness connector C146 (male side). See WIRING DIAGRAMS .
  4. Turn ignition switch to LOCK position. Ensure ABS connector is disconnected. Turn ignition switch to RUN position. Using WDS or NGS tester, perform data link diagnostics network test. See DATA LINK DIAGNOSTICS NETWORK TEST  under SELF-DIAGNOSTIC SYSTEM. If scan tool indicates SYSTEM PASSED, go to step  18. If scan tool does not indicate SYSTEM PASSED, go to next step.
  5. Turn ignition switch to LOCK position. Connect ABS harness connector C135. If vehicle has Overhead Trip Computer (OTC), go to next step. If vehicle does not have OTC, go to step  9.
  6. Measure resistance of Light Blue/White wire between OTC harness connector C945 terminal No. 1 and Data Link Connector (DLC) terminal No. 7. See Figure and Figure . If resistance is less than 5 ohms, go to step  8. If resistance is 5 ohms or more, go to next step.
  7. Disconnect in-line 14-pin connector C222. Inspect in-line 14-pin connector C222 for loose, damaged or corroded terminals. Repair connector as necessary. Measure resistance in Light Blue/White wire between DLC terminal No. 7 and in-line harness connector C222 (male side) terminal No. 13. See Figure and Figure . If resistance is less than 5 ohms, repair open in Light Blue/White wire between in-line harness connector C122 (female side) and OTC connector. If resistance is greater than 5 ohms, repair open in Light Blue/White wire between in-line harness connector C222 (male side) and DLC. See WIRING DIAGRAMS .
  8. Ensure OTC harness connector C945 is disconnected. Turn ignition switch to RUN position. Using WDS or NGS tester, perform data link diagnostics network test. See DATA LINK DIAGNOSTICS NETWORK TEST  under SELF-DIAGNOSTIC SYSTEM. If scan tool displays SYSTEM PASSED, go to step  19. If scan tool does not display SYSTEM PASSED and vehicle is equipped with 4WD, go to next step. If scan tool does not display SYSTEM PASSED and vehicle is not equipped with 4WD, go to step  11.
  9. Turn ignition switch to LOCK position. Connect OTC harness connector C945. Disconnect 4-wheel drive control module harness connector C281a. Measure resistance of Light Blue/White wire between 4-wheel drive control module harness connector C281a terminal No. 25 and Data Link Connector (DLC) terminal No. 7. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Blue/White wire between DLC and 4-wheel drive control module connector C281a.
  10. Ensure 4-wheel drive control module harness connector C281a is disconnected. Turn ignition switch to RUN position. Using WDS or NGS tester, perform data link diagnostics network test. See DATA LINK DIAGNOSTICS NETWORK TEST  under SELF-DIAGNOSTIC SYSTEM. If scan tool displays SYSTEM PASSED, go to step  20. If scan tool does not display SYSTEM PASSED, go to next step.
  11. Turn ignition switch to LOCK position. Connect OTC harness connector C945. Connect 4-wheel drive control module harness connector C281a. Disconnect Restraints Control Module (RCM) harness connector C2041. Measure resistance of Light Blue/White wire between RCM harness connector C2041 terminal No. 5 and Data Link Connector (DLC) terminal No. 7. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Blue/White wire between DLC and RCM. See WIRING DIAGRAMS .
  12. Ensure RCM harness connector C2041 is disconnected. Turn ignition switch to RUN position. Using WDS or NGS tester, perform data link diagnostics network test. See DATA LINK DIAGNOSTICS NETWORK TEST  under SELF-DIAGNOSTIC SYSTEM. If scan tool displays SYSTEM PASSED, go to step  21. If scan tool does not display SYSTEM PASSED, go to next step.
  13. Turn ignition switch to LOCK position. Connect RCM harness connector C2041. If vehicle has Parking Aid Module (PAM), go to next step. If vehicle does not have a PAM, retest system. If system is okay, problem may have been caused by a loose or corroded connector.
  14. Measure resistance of Light Blue/White wire between PAM connector C4014 terminal No. 5 and Data Link Connector (DLC) terminal No. 7. See Figure and Figure . If resistance is less than 5 ohms, go to step  17. If resistance is 5 ohms or more, go to next step.
  15. Disconnect in-line connector C211. In-line harness connector C211 is located behind right side of instrument panel. Inspect in-line connector C211 for loose, damaged or corroded terminals. Repair connector as necessary. Measure resistance in Light Blue/White wire between in-line harness connector C211 (male side) terminal No. 2 and DLC connector terminal No. 7. See Figure and Figure . On Excursion, if resistance is less than 5 ohms, go to next step. On Pickups, if resistance is less than 5 ohms, repair open in Light Blue/White wire between in-line harness connector C211 (female side) and PAM harness connector C4014. See WIRING DIAGRAMS . On all models, if resistance is greater than 5 ohms, repair open circuit between in-line harness connector C211 (male side) and DLC. See WIRING DIAGRAMS .
  16. Disconnect in-line harness connector C339. In-line harness connector C339 is located on right side C-pillar. Inspect in-line connector C339 for loose, damaged or corroded terminals. Repair connector as necessary. Measure resistance in Light Blue wire between in-line harness connector C211 (female side) terminal No. 2 and in-line harness connector C339 (male side) terminal No. 10. See Figure. If resistance is less than 5 ohms, repair open in Light Blue/White wire between in-line harness connector C339 (female side) and PAM harness connector C4014. If resistance is greater than 5 ohms, repair open in Light Blue/White wire between in-line harness connector C211 (female side) and in-line harness connector C339 (male side). See WIRING DIAGRAMS .
  17. Ensure PAM harness connector C4014 is disconnected. Turn ignition switch to RUN position. Using WDS or NGS tester, perform data link diagnostics network test. See DATA LINK DIAGNOSTICS NETWORK TEST  under SELF-DIAGNOSTIC SYSTEM. If scan tool displays SYSTEM PASSED, go to step  22. If scan tool does not display SYSTEM PASSED, system is operating properly at this time, problem may have been caused by a loose or corroded connector.
  18. Disconnect all ABS connectors and inspect for loose, damaged or corroded terminals. Repair connector as necessary. Reconnect all connectors. Operate system to verify problem. If problem is present, replace ABS module. See appropriate ANTI-LOCK article in BRAKES. If problem no longer exists, problem may have been caused by poor contact at connector.
  19. Disconnect all OTC connectors and inspect for loose, damaged or corroded terminals. Repair connector as necessary. Reconnect all connectors. Operate system to verify problem. If problem is present, replace OTC module. If problem no longer exists, problem may have been caused by poor contact at connector.
  20. Disconnect all 4-wheel drive control module harness connectors and inspect for loose, damaged or corroded terminals. Repair connector as necessary. Reconnect all connectors. Operate system to verify problem. If problem is present, replace 4-wheel drive control module. If problem no longer exists, problem may have been caused by poor contact at connector.
  21. Disconnect all RCM connectors and inspect for loose, damaged or corroded terminals. Repair connector as necessary. Reconnect all connectors. Operate vehicle to verify problem. If problem is present, replace RCM. See RESTRAINTS CONTROL MODULE under REMOVAL & INSTALLATION in appropriate INSTRUMENT PANELS article. If problem no longer exists, problem may have been caused by poor contact at connector.
  22. Disconnect all PAM connectors and inspect for loose, damaged or corroded terminals. Repair connector as necessary. Reconnect all connectors. Operate system to verify problem. If problem is present, replace PAM. See REMOVAL & INSTALLATION in appropriate PARKING AID SYSTEMS article. If problem no longer exists, problem may have been caused by poor contact at connector.
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