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Home >> Oldsmobile >> 1998 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1667 - Fuel Pump PWM Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. Turn ignition off. Disconnect PCM harness connector and fuel pump relay. Using a fused jumper wire, jumper between fuel pump relay connector terminals No. 30 and 87. Turn ignition on. Using DVOM, check voltage between ground and fuel pump speed control PWM circuit at PCM harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
  3. Check current between ground and fuel pump speed control PWM circuit at PCM connector. Monitor reading for at least 2 minutes. If current remains between .001-.500 amp, go to step 11). If current reading does not remain between .001-.500 amp, go to next step.
  4. Turn ignition off. Disconnect fuel pump control module connector. Leave PCM connector disconnected. Turn ignition on. Check voltage between fuel pump speed control PWM circuit and ground. If voltage reading is zero volts, go to step 10). If voltage reading is not zero volts, go to next step.
  5. Locate and repair short to voltage in fuel pump speed control PWM circuit. After repairs, go to step 18).
  6. Check ignition feed fuse fro fuel pump relay. If fuse is blown, go to next step. If fuse is okay, go to step 8).
  7. Locate and repair short to ground in ignition feed circuit for fuel pump relay. Replace fuse. After repairs, go to step 18).
  8. Disconnect fuel pump control module. Turn ignition on. Check voltage between ground and ignition feed circuit for fuel pump control module. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step 13).
  9. Check fuel pump speed control PWM circuit for open or short to ground. Repair as necessary. After repairs, go to step 18). If circuit is okay, go to next step.
  10. Check fuel pump speed control PWM circuit for poor connection to PCM or fuel pump control module. Check fuel pump control module ignition feed circuit for poor connection at fuel pump control module. Repair as necessary. After repairs, go to step 18). If connections are okay, go to step 14).
  11. Turn ignition off. Reconnect PCM harness connector. Disconnect fuel pump control module. Turn ignition on. Using test light, connect test light between fuel pump speed control PWM circuit and ignition feed circuit at fuel pump control module harness connector. Using scan tool, cycle fuel pump PWM output on and off. If test light flashes on and off, go to step 16). If test light does not flash on and off, go to next step.
  12. Check fuel pump speed control PWM circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 18). If connection is okay, go to step 15).
  13. Locate and repair open in ignition feed circuit to fuel pump relay or between fuel pump relay and fuel pump control module. Repair as necessary. After repairs, go to step 18).
  14. Replace fuel pump control module. After replacing control module, go to step 18).
  15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 18).
  16. Check for poor connection at fuel pump relay. Repair as necessary. After repairs, go to step 18). If connection is okay, go to next step.
  17. Replace fuel pump relay. After replacing relay, go to next step.
  18. 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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