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Home >> Chevrolet >> 1997 >> Corvette Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing 5.7L >> On-Board Diagnostic (OBD) System Check >> DLC Diagnosis Or No Scan Tool Data
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DLC Diagnosis Or No Scan Tool Data

  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . After performing OBD system check, go to next step.
  2. Turn ignition on with engine off. Connect scan tool to Data Link Connector (DLC). If scan tool powers up, go to next step. If scan tool does not power up, go to step 5).
  3. Turn ignition off for 15 seconds. Immediately attempt to start engine. If engine is not cranked within 5 seconds after ignition is turned on, misdiagnosis could occur. If engine starts and then stalls after about 5 seconds, go to the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section. If engine does not start or does not start and stall after about 5 seconds, go to next step.
  4. If engine cranks but does not start, go to step 9). If engine does not crank, go to step 13).
  5. Disconnect scan tool from DLC. Turn ignition on, with engine off. Using a test light connected to ground, probe DLC terminal No. 16 (Purple wire). See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 16).
  6. Using a test light connected to battery voltage, probe DLC terminals No. 4 (Black wire) and No. 5 (Black/White wire). See the WIRING DIAGRAMS article. If test light illuminates on both circuits, go to next step. If test light does not illuminate on either circuit, go to step 8).
  7. Inspect scan tool connections to DLC. Also, inspect DLC terminals for proper tension. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  8. Repair open in ground circuit to DLC terminals No. 4 (Black wire) and No. 5 (Black/White wire). After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  9. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector C2 (Blue). Turn ignition on. Using a test light connected to battery ground, probe PCM connector C2, terminals No. 19 (Pink wire - PCM ignition 1 feed), No. 20 (Orange wire - PCM battery feed), and No. 61 (Orange wire - PCM battery feed). See the WIRING DIAGRAMS article. If test light illuminates on each circuit, go to next step. If test light does not illuminate on any circuit, go to step 14).
  10. Using DVOM, measure resistance between chassis ground and PCM connector C2 terminals No. 21 (Black/White wire - PCM ground), and No. 60 (Black/White wire - PCM ground). See the WIRING DIAGRAMS article. If resistance is equal to or less than 5 ohms on both circuits, go to next step. If resistance is greater than 5 ohms on either circuit, go to step 15).
  11. Check PCM for proper connections. Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . If no problem is found, go to next step.
  12. Replace PCM. Perform PCM relearn procedures. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  13. Repair open in Class 2 circuit (Dark Green wire) between splice pack and PCM. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  14. Repair circuit that did not illuminate test light. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  15. Repair faulty PCM ground circuit (Black/White wire). After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
  16. Repair faulty battery supply circuit (Purple wire). After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
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