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Home >> GMC >> 1999 >> Yukon Base, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Data Link Communications System >> System Tests >> Scan Tool Inoperative

Scan Tool Inoperative

  1. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Ensure scan tool is operating correctly by connecting scan tool to a different vehicle. If scan tool is functioning properly, return to original vehicle and go to next step. If scan tool is malfunctioning, refer to scan tool owners manual.
  3. Ensure ignition is OFF. Connect a test lamp between DLC terminal No. 16 and ground. If the test lamp lights, go to next step. If the test light does not light, go to step  6.
  4. Connect a test lamp between DLC terminals No. 16 and 4, then between DLC terminals No. 16 and 5. If the test lamp lights on both tests, go to next step. If the test lamp does not light on both tests, go to step  7.
  5. Inspect the DLC power and ground circuits for intermittent or poor connections. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  6. Repair open in the Orange 840 circuit wiring between the AUX POWER fuse and the DLC. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  7. Repair open in the Black 150 circuit or the Black/White 451 circuit wiring between ground and the DLC. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
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