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

  1. Turn ignition off. Inspect Data Link Connector (DLC) for physical damage, bent terminals or corrosion. Pay particular attention to terminal No. 7 (Light Blue/White wire). Repair connector as necessary and retest system for normal operation. If connector is okay, go to next step.
  2. Ensure ignition is off. Disconnect GEM 26-pin connector located behind center of instrument panel. Measure resistance of Light Blue/White wire between terminal No. 25 at GEM 26-pin connector and terminal No. 7 at DLC. See Figure and Figure. If resistance is 5 ohms or more, repair open Light Blue/White wire between DLC and splice and wiring harness splice S225. Splice is located in main wiring harness near breakout to GEM. Retest system for normal operation. If resistance is less than 5 ohms, reconnect GEM connector. Proceed as follows:
    • If vehicle is equipped with a Remote Anti-Theft Personality RAP) module and a 4-Wheel Anti-Lock Brake System (4WABS) module, go to next step.
    • If vehicle is equipped with a RAP module only, go to next step.
    • If vehicle is equipped with a 4WABS module only, go to step 4).
    • If vehicle is not equipped with a RAP module or a 4WABS module, go to step 5).
      NOTE: ISO 9141 communication network (circuit No. 70) will not function if circuit No. 70 (Light Blue/White wire) is shorted to ground or power. Steps 3-9 are used for locating a short in circuit No. 70.
  3. Disconnect 84-pin in-line connector C201 located behind left corner of instrument panel. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. Both readings should indicate zero volts. If any reading indicates voltage, go to next step (vehicles with 4WABS) or go to step 5) (vehicles without 4WABS). If both readings indicate zero volts, go to step 7).
  4. Turn ignition off. Disconnect 40-pin bulkhead connector C134 located at left rear of engine compartment. See Figure, Figure or Figure. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. If any reading indicates voltage, go to next step. If both readings indicate zero volts, go to step 8).
  5. Turn ignition off. Disconnect GEM 26-pin connector located behind center of instrument panel. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. If any reading indicates voltage, go to next step. If both readings indicate zero volts, replace GEM and retest system for normal operation.
  6. Turn ignition off. Deactivate air bag system. See appropriate AIR BAG RESTRAINT SYSTEM article. Disconnect air bag diagnostic monitor connector. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. If any reading indicates voltage, repair circuit No. 70 (Light Blue/White wire) between DLC and air bag diagnostic monitor connector, GEM connector, 84-pin in-line connector C201 or 40-pin bulkhead connector C134. Retest system for normal operation. If both readings indicate zero volts, replace air bag diagnostic monitor and retest system for normal operation.
  7. Turn ignition off. Reconnect connector C201. Disconnect RAP module 26-pin connector located at left rear corner of cab. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. If any reading indicates voltage, repair circuit No. 70 (Light Blue/White wire) between connector C201 and RAP module connector. If both readings indicate zero volts, replace RAP module and retest system for normal operation.
  8. Turn ignition off. Reconnect 40-pin bulkhead connector C134. Disconnect 25-pin 4WABS module connector located at left side of engine compartment. See Figure, Figure or Figure. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. If any reading indicates voltage, go to next step. If both readings indicate zero volts, replace 4WABS module and retest system for normal operation.
  9. Turn ignition off. Disconnect 40-pin bulkhead connector C179 located at left rear of engine compartment. See Figure, Figure or Figure. Turn ignition on. Measure voltage between terminals No. 7 (Light Blue/White wire) and No. 16 (Orange wire) at DLC. See Figure. Also, measure voltage between terminals No. 7 (Light Blue/White wire) and No. 4 (Black wire) at DLC. If any reading indicates voltage, repair circuit No. 70 (Light Blue/White wire) between connector C134 and connector C179. Retest system for normal operation. If both readings indicate zero volts, repair circuit No. 70 (Light Blue/White wire) between connector C179 and 4WABS module. Retest system for normal operation.
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