LEMON Manuals: Even more car manuals for everyone
Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.1L >> Diagnostic Trouble Codes >> DTC P1654 - A/C Relay Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and A/C relay driver circuit terminal 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. Measure current between ground and A/C relay driver circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 11). If current is not .5-1.5 amps, go to next step.
  4. Ignition off. Disconnect A/C relay connector. Ignition on. Using DVOM, measure voltage between ground and A/C relay driver circuit at A/C relay harness connector. 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 A/C relay driver circuit. After repair is completed, go to step 16).
  6. Remove and inspect fuse for A/C 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 A/C relay. Replace fuse. After repair is completed, go to step 16).
  8. Disconnect A/C relay. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at A/C relay harness connector. 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 A/C relay driver circuit. Repair as necessary. After repair is completed, go to step 16). If circuit is okay, go to next step.
  10. Check A/C relay driver circuit and ignition feed circuit for poor terminal connection at A/C relay connector and at PCM connector. Repair as necessary. After repair is completed, go to step 16). If connections are okay, go to step 14).
  11. Turn ignition off. Reconnect PCM connector. Disconnect A/C relay connector. Turn ignition on. Connect a test light between A/C relay driver circuit and ignition feed circuit terminals at A/C relay harness connector. Using scan tool, select OUTPUTS TEST function and cycle A/C relay on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
  12. Check A/C relay driver circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 16). If connection is okay, go to step 15).
  13. Locate and repair open in ignition feed circuit to A/C relay. After repair is completed, go to step 16).
  14. Replace A/C relay. After repair is completed, go to step 16).
  15. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  16. 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 DTC P1654 until DTC P1654 test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.
scientia non olet · About LEMON Manuals