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Home >> Oldsmobile >> 1996 >> Bravada >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures - 4.3L >> On-Board Diagnostic (OBD) System Check >> A-2, No Scan Tool Data
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A-2, No Scan Tool Data

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . After performing OBD system check, go to next step.
  2. Turn ignition off for 30 seconds. Turn ignition on with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, go to A-1, MALFUNCTION INDICATOR LIGHT (MIL)  .
  3. Install scan tool. If scan tool communicates with VCM, go to next step. If scan tool does not communicate with VCM, go to step 5).
  4. Using scan tool, command MIL to turn on and off. If MIL turns on and off as commanded, go to step 17). If MIL does not turn on or off as commanded, go to next step.
  5. Turn ignition off. Disconnect VCM connectors. Turn ignition on. Observe MIL. If MIL illuminates, go to step 18). If MIL does not illuminate, go to next step.
  6. Using scan tool, check engine calibration ID. If proper ID is displayed, go to step 28). If proper ID not displayed, go to step 19).
  7. Connect a test light to ground. Using test light, probe DLC terminal No. 16. See Figure . If test light illuminates, go to next step. If test light does not illuminate, go to step 20).
  8. Connect a test light to battery voltage. Using test light, probe DLC terminals No. 4 and 5. If test light illuminates on both circuits, go to next step. If test light does not illuminate on either circuit, go to step 21).
  9. Check cigarette lighter for power. If power is present at cigarette lighter, go to next step. If power is not present at cigarette lighter, go to step 22).
  10. Install and check scan tool on another vehicle. If scan tool works, go to next step. If scan tool does not work, go to step 23).
  11. Disconnect scan tool. Using DVOM, check voltage between ground and VCM serial data line at DLC terminal No. 2. See Figure . DVOM should read 7 volts. If voltage is less than 7 volts, go to next step. If voltage is 7 volts or greater, go to step 15).
  12. Using DVOM, again check voltage between ground and DLC terminal No. 2. DVOM should read 1 volt. If voltage is less than 1 volt, go to next step. If voltage is 1 volt or greater, go to step 27).
  13. Turn ignition off. Using DVOM, check resistance between ground and DLC terminal No. 2. Resistance should be 10 ohms. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or greater, go to step 27).
  14. Disconnect VCM connectors. Using DVOM, check resistance between ground and DLC terminal No. 2. Resistance should be 10 ohms. If resistance is less than 10 ohms, go to step 24). If resistance is 10 ohms or greater, go to step 26).
  15. Turn ignition off. Disconnect VCM connectors. Turn ignition on. Check voltage on DLC terminal No. 2. Voltage should not be present. If voltage is not as specified, go to step 25). If voltage is as specified, go to step 27).
  16. Reprogram EEPROM and retest. If serial data is present, go to step 27). If serial data is not present, go to step 26).
  17. System is okay. Proceed to step 27).
  18. Repair short to ground in MIL control circuit (Brown/White wire). See Figure . After repairs, go to step 27).
  19. Reprogram EEPROM and retest. After repairs, go to step 27).
  20. Check fuse No. 7 (PWR AUX). If fuse is faulty, repair short to ground in DLC terminal No. 16 circuit (Orange wire). If fuse is okay, repair open in DLC terminal No. 16 circuit (Orange wire). After repairs, go to step 27).
  21. Repair open in affected circuit. After repairs, go to step 27).
  22. Repair cigarette lighter circuit. After repairs, go to step 27).
  23. Repair or replace faulty scan tool and/or cables. After repairs, go to step 27).
  24. Repair short to ground in serial data line (Purple wire). After repairs, go to step 27).
  25. Repair short to voltage in serial data line (Purple wire). After repairs, go to step 27).
  26. Check for open in serial data line. If circuit is okay, check VCM and DLC connectors. If connectors are okay, replace VCM. Perform VCM relearn procedures. After repairs, go to next step.
  27. Using scan tool, select DTC, CLEAR INFO function. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start or starts and dies/stalls, go to step 2).
  28. Warm engine to normal operating temperature. Using scan tool, select DTC, FAILED THIS IGN function. If any DTC(s) are stored, diagnose DTC. See TESTS W/CODES article. If DTC(s) are not present, go to next step.
  29. Select CAPTURE INFO, REVIEW INFO function. If additional DTC(s) are displayed, diagnose DTC. See TESTS W/CODES article.
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