LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Buick >> 1996 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1663 - Change Oil Light Control Circuit >> Diagnostic Procedures
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command CHANGE OIL light on and off. If light turns on and off with each command, see DIAGNOSTIC AIDS. If light does not turn on and off with each command, go to next step.
  3. Turn ignition off. Disconnect PCM connector containing the light control circuit. Turn ignition on. If CHANGE OIL light illuminates, go to step 5). If CHANGE OIL light does not illuminate, go to next step.
  4. Using a fused jumper wire, jumper CHANGE OIL light control circuit in PCM harness connector and ground. If light illuminates, go to step 6). If light does not illuminate, go to step 7).
  5. Repair short to ground in CHANGE OIL light control circuit. After repairs, go to step 9).
  6. Check PCM connections. Repair as necessary. After repairs, go to step 9). If connections are okay, go to step 8).
  7. Check for faulty light bulb, open ignition feed to bulb, open control circuit or circuit shorted to battery voltage. Repair as necessary. After repairs, go to step 9).
  8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1663. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
scientia non olet · About LEMON Manuals