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Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.1L >> Diagnostic Trouble Codes >> DTC P1663 - Generator Light Control Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Perform a function system check of all instrument cluster gauges and warning light indicators. If generator light is on, go to next step. If system is not functioning properly (gauges or warning lights inoperative), repair as necessary. See appropriate INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT section.
  3. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, measure voltage between ground and generator light control circuit terminal at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 7).
  4. Set ammeter to 10-amp range. Measure current between ground and generator light control circuit terminal at PCM connector. Monitor reading for a minimum of 2 minutes. If current is .5-1.5 amps, go to step 12). If current is not .5-1.5 amps, go to next step.
  5. Disconnect instrument panel cluster connector. Using DVOM, check voltage between ground and generator control circuit at instrument cluster connector. If voltage reading is zero volts, go to step 15). If voltage reading is greater than zero volts, go to next step.
  6. Locate and repair short to voltage in generator light control circuit. After repair is completed, go to step 3).
  7. Remove and inspect fuse for generator light control circuit. If fuse is blown, go to next step. If fuse is okay, go to step 9).
  8. Locate and repair short to ground in ignition feed circuit for instrument cluster indicator lights. Replace fuse. After repair is completed, go to step 3).
  9. Disconnect instrument cluster connector. Turn ignition on. Measure voltage between ground and ignition feed circuit terminal at instrument panel cluster connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 14).
  10. Check for an open or short to ground in generator light control circuit. Repair as necessary. After repair is completed, go to step 3). If circuit is okay, go to next step.
  11. Check generator light control circuit and ignition feed circuit for poor terminal connection at instrument panel cluster connector and at PCM connector. Repair as necessary. After repair is completed, go to step 3). If connections are okay, go to step 15).
  12. Turn ignition off. Reconnect PCM connector. Disconnect instrument panel cluster connector. Turn ignition on. Connect a test light between generator light control circuit and ignition feed circuit terminals at instrument cluster connector. Using scan tool, select OUTPUTS TEST function and cycle generator light on and off. If test light flashes, see DIAGNOSTIC AIDS. If test light does not flash, go to next step.
  13. Check generator light control circuit for poor terminal connection at PCM. Repair as necessary. After repair is completed, go to step 3). If connection is okay, go to step 16).
  14. Locate and repair open in ignition feed circuit to instrument cluster indicator lights. After repair is completed, go to step 3).
  15. Replace instrument cluster. After repair is completed, go to step 3).
  16. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  17. 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 P1655 until DTC P1655 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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