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Home >> Oldsmobile >> 1998 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1671 - Mil Control Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, check voltage between ground and MIL control circuit at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).
  3. Set ammeter to 10-amp range. Check current between ground and MIL control circuit at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .05-.50 amp, go to step 11). If current is not .05-.50 amp, go to next step.
  4. Disconnect instrument panel cluster connector. Using DVOM, check voltage between ground and MIL control circuit at harness connector. 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 MIL control circuit. After repairs, go to step 15).
  6. Check ignition feed fuse for instrument panel indicators. 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 instrument panel indicators. Replace fuse. After repairs, go to step 15).
  8. Disconnect instrument cluster connector. Turn ignition on. Check voltage between ground and ignition feed circuit for instrument cluster indicators. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).
  9. Check for an open or short to ground in MIL control circuit. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to next step.
  10. Check MIL control circuit and ignition feed circuit for poor terminal connection at instrument cluster and at PCM connector. Repair as necessary. After repairs, go to step 15). If connections are okay, diagnose instrument cluster assembly.
  11. Turn ignition off. Reconnect PCM harness connector. Disconnect instrument cluster connector. Turn ignition on. Connect a test light between MIL control circuit and ignition feed circuit terminals at instrument panel connector. Using scan tool, select OUTPUTS TEST function and cycle MIL on and off. If test light flashes on and off, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
  12. Check MIL control circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 15). If connection is okay, go to step 15).
  13. Locate and repair open in ignition feed circuit to instrument cluster indicators. After repairs, go to step 15).
  14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  15. 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, repair is complete.
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