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Home >> Oldsmobile >> 2000 >> Intrigue GL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1635: 5-Volt Reference "A" Circuit >> Diagnostic Procedures

Diagnostic Procedures

  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. Inspect PCM and engine grounds. Ensure grounds are clean and tight. Repair as necessary. After repairs, go to step  11. If grounds are okay, go to next step.
  3. Check if any other DTCs are set. If any other DTCs are set, diagnose affected DTCs. If no other DTCs are set, go to next step.
  4. Turn ignition off. Disconnect harness connector to TP, MAP, EGR and oil pressure sensor. Turn ignition on. Using DVOM, check voltage between sensor ground circuit and 5-volt reference "A" circuit terminals of each sensor. If voltage reading is 4.5-5.5 volts, go to next step. If voltage reading is not 4.5-5.5 volts, go to step  8.
  5. Reconnect one disconnected component at a time while check voltage on 5-volt reference circuit at one of the other sensors. If sensor being reconnected causes voltage to go out of range (4.5-5.5 volts), go to next step. If voltage does not go out of range, see DIAGNOSTIC AIDS .
  6. Check for short to power or ground on circuit to affected sensor/component. Repair as necessary. After repairs, go to step  11. If circuit is okay, go to next step.
  7. Replace affected sensor/component. After repairs, go to step  11.
  8. Turn ignition on. Disconnect PCM harness connector. Turn ignition on. Check 5-volt reference "A" circuit for short to ground or power. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step  10.
  9. Repair 5-volt reference circuit. After repairs, go to step  11.
  10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  11. Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. If scan tool indicates FAILED THIS IGN, repeat step  2. If scan tool does not indicate FAILED THIS IGN, go to next step.
  12. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, go to affected DTC test.
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