LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2000 >> Cutaway 7.4 J >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Data Link Communications System >> System Tests >> Scan Tool Does Not Power Up >> Diagnostic Procedure

Diagnostic Procedure

Disconnecting modules and turning ignition switch to RUN position may cause DTCs in these modules. Inspect for DTCs in each module upon completion of required repair. Ensure that theft deterrent system has not caused a Class 2 No Communication malfunction.

  1. If scan tool powers up, go to next step. If scan tool does not power up, go to step  4 .
  2. Connect scan tool to a similar vehicle. Turn ON ignition leaving engine OFF. Ensure all scan tool functions are operating. If scan tool is operating properly, go to next step. If scan tool is malfunctioning, refer to scan tool owners manual.
  3. Return to original vehicle and turn ignition to OFF position. Disconnect scan tool from Data Link Connector (DLC). Inspect for poor connections/terminal tension at DLC terminals No. 2, 4, 5 and 16. See Figure . If there is no fault with DLC connections or terminals, go to next step. If there is fault with DLC, repair and perform diagnostic system check for each module. See:
  4. Test DLC 150 circuit (Black wire) ground at terminal No. 4, 451 circuit (Black/White wire) ground and 551 circuit (Tan/White wire) ground at terminal No. 5 for an open. See Figure . If there is no fault with grounds, go to next step. If there is a fault with grounds, repair and perform diagnostic system check for each module. See:
  5. Check for battery voltage at DLC terminal No. 16 (840 circuit - Orange wire). See Figure . If there is battery voltage, go to next step. If there is not battery voltage, go to step  9 .
  6. Test Class 2 serial data 1807 circuit (Purple wire) for an open or short to ground. See Figure . If there is no fault with 1807 circuit, go to next step. If there is a fault with 1807 circuit, repair and perform diagnostic system check for each module. See:
  7. Disconnect each module one at a time while monitoring Class 2 serial data CKT 1807 (PPL) for a short to ground. See Figure . If a short is removed after a module is disconnected, replace module with an internal short. See:
  8. If short is not removed after disconnecting all modules, repair open or high resistance in 1807 circuit (Purple wire). Perform diagnostic system check for each module after replacing module or repairing short in 1807 circuit. See: If short is not removed after disconnecting all modules, repair open or high resistance in 1807 circuit (Purple wire).
  9. Repair open or high resistance in 840 circuit (Orange wire). See Figure . Perform diagnostic system check for each module. See:

scientia non olet · About LEMON Manuals