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Home >> Oldsmobile >> 1998 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1646 - Boost Control Solenoid Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
  2. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a DVOM, check voltage between engine ground and PCM harness connector boost control solenoid driver circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
  3. Using DVOM in 10-amp scale, check current between engine ground and boost control solenoid driver circuit for 2 minutes. If current remains .05-.80 amp go to step 11). If current does not remain between .05-.80 amp, go to next step.
  4. Turn ignition off. Leave PCM connector disconnected. Disconnect boost control solenoid connector. Turn ignition on. Using DVOM, check voltage between engine ground and boost control solenoid driver circuit. If voltage is zero volts, go to step 10). If voltage is greater than zero volts, go to next step.
  5. Locate and repair short to voltage in boost control solenoid driver circuit. After repairs, go to step 16).
  6. Check boost control solenoid ignition feed fuse. If fuse is blown, go to next step. If fuse is okay, go to step 8).
  7. Locate and repair short to ground in boost control solenoid ignition feed circuit. Replace fuse. After repairs, go to step 16).
  8. Disconnect boost control solenoid connector. Turn ignition on. Check voltage between engine ground and boost control solenoid ignition feed circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
  9. Check boost control solenoid driver circuit for open or short to ground. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to next step.
  10. Check boost control solenoid driver and boost control solenoid ignition feed circuits for faulty connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 14).
  11. Turn ignition off. Reconnect PCM connector. Disconnect boost control solenoid connector. Turn ignition on. Connect a test light between boost control solenoid harness connector boost control solenoid driver and ignition feed circuits. Using scan tool, cycle boost control solenoid on and off. If test light flashes on and off, see DIAGNOSTIC AIDS. If test light does not flash on and off, go to next step.
  12. Check boost control solenoid driver circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 15).
  13. Locate and repair open boost control solenoid ignition feed circuit. After repairs, go to step 16).
  14. Replace boost control solenoid. After replacing boost control solenoid, go to step 16).
  15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  16. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2). If scan tool does not display that this DTC FAILED THIS IGN, repair is complete.
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