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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (Engine Controls Self-Diagnostics - 5.0L & 5.7L) >> Diagnostic Tests >> DTC P0140 & P0160: Ho2S Circuit - Insufficient Activity - Bank 1 & 2, Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

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  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
    2. NOTE: Allow engine to cool for one-half hour before proceeding with this diagnostic. This allows HO2S signal voltage to return to bias voltage, approximately 447 millivolts.
  2. Install scan tool. Turn ignition on, engine off. Immediately observe affected HO2S voltage for 2 minutes. If HO2S voltage goes from bias voltage to more or less than 350-550 millivolts, go to next step. If HO2S voltage does not go from bias voltage to more or less than 350-550 millivolts, go to step  5.
  3. Start engine. Allow engine to reach operating temperature. Raise and hold engine speed at 1200 RPM for 2 minutes. Using scan tool, observe HO2S voltage. If HO2S voltage is varying outside 400-475 millivolts, go to next step. If HO2S voltage is not varying outside 400-475 millivolts, go to step  5.
  4. Observe FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME/FAILURE RECORDS data as possible. If DTC failed this ignition cycle, go to next step. If DTC did not fail this ignition cycle, see DIAGNOSTIC AIDS .
  5. Disconnect affected HO2S connector. Turn ignition on, engine off. Connect jumper wire between HO2S connector terminal "A" (Tan wire or Tan/White wire) and ground, and between HO2S connector terminal "B" (Purple wire or Purple/White wire) and ground. See Figure. Using scan tool, observe HO2S voltage. If HO2S voltage is less than 200 millivolts, go to step  9. If HO2S voltage is not less than 200 millivolts, go to next step.
  6. Remove both jumper wires from HO2S connector. Measure voltage between HO2S connector terminal "A" (Tan wire or Tan/White wire) and ground. If voltage is more than 4.5 volts, go to next step. If voltage is not more than 4.5 volts, go to step  8.
  7. Turn ignition off. Disconnect PCM Blue connector C1. Check Purple wire between HO2S and PCM for open. If problem was found, repair as necessary. After repairs, go to step  21. If problem was not found, go to step  16.
  8. Turn ignition off. Disconnect PCM Blue connector C1. Check Tan wire or Tan/White wire between HO2S and PCM for open. If problem was found, repair as necessary. After repairs, go to step  21. If problem was not found, go to step  16.
  9. Remove jumpers from previous step. Check ENG-1 fuse (20-amp). ENG-1 fuse is located in underhood fuse block. If ENG-1 fuse is open, go to step  12. If ENG-1 fuse is not open, go to next step.
  10. Turn ignition on, engine off. Using test light connected to ground, probe affected HO2S connector terminal "D" (Pink wire). If test light is on, go to next step. If test light is off, go to step  17.
  11. Connect a test light between affected HO2S connector terminals "C" (Black wire) and "D" (Pink wire). Turn ignition on, engine off. If test light is on, go to step  15. If test light is off, go to step  18.
  12. Disconnect opposite bank HO2S connector. Check Pink wire between HO2S and PCM for short to ground. Replace ENG-1 fuse if necessary. If problem was found, repair as necessary. After repairs, go to step  21. If problem was not found, go to next step.
    13. NOTE: Perform the following test on HO2S bank 1, sensor 2 and HO2S bank 2, sensor 2. A condition in either sensor will cause this DTC to set.
  13. Check wire between HO2S connector terminal "D" and HO2S for short to HO2S body. If problem was found, repair as necessary. After repairs, go to step  19. If problem was not found, go to next step.
    14. NOTE: Perform the following test on HO2S bank 1, sensor 2 and HO2S bank 2, sensor 2. A condition in either sensor will cause this DTC to set.
  14. Measure resistance between HO2S connector terminals "C" and "D" (sensor side). If resistance of either sensor is more or less than 2-50 ohms, go to step  19. If resistance of either sensor is not more or less than 2-50 ohms, see DIAGNOSTIC AIDS .
  15. Check HO2S connector for poor connections. If problem was found, repair as necessary. After repairs, go to step  21. If problem was not found, go to step  19.
  16. Check PCM connectors for poor connections. If problem was found, repair as necessary. After repairs, go to step  21. If problem was not found, go to step  20.
  17. Repair open in Pink wire between HO2S and underhood fuse block. After repairs, go to step  21.
  18. Repair open in Black wire between HO2S and ground. After repairs, go to step  21.
  19. Replace affected HO2S. After repairs, go to step  21.
  20. Replace PCM. Program PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  21. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step  2.
  22. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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