Daytime Running Light Diagnostic System Check

1998 Oldsmobile Achieva 3.1 M, 4T40E/MN4SECTION Daytime Running Light Diagnostic System Check
WARNING: This page is about a different car, the 1999 Pontiac Grand Am and 1999 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn the headlight switch to the HEAD position. Turn the headlight dimmer switch to the LOW position. The low beam headlights should be ON and the high beam headlights should be OFF. If headlights operate as specified, go to next step. If headlights do not operate as specified, repair as necessary. See HEADLIGHTS in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  2. Turn the headlight switch to the HIGH position. The high beam headlights should be ON. The high beam indicator should be ON. The low beam headlights should be OFF. If headlights do not operate as specified, repair as necessary. See HEADLIGHTS in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  3. Turn the headlight switch OFF. Turn the ignition to ON. Place the transaxle in gear. Apply a bright light to the Daytime Running Lamps (DRL) ambient light sensor. The high beam headlights should come ON at a reduced intensity in approximately 30 seconds. If Daytime Running Lamps do not operate as specified, repair as necessary. See HEADLIGHTS in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  4. Cover the DRL ambient light sensor with a dark cloth. The high beam headlights should turn OFF, the low beam headlights should turn ON and the exterior lamps should turn ON within approximately 15 seconds. If headlights do not operate as specified, repair as necessary. See HEADLIGHTS in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  5. Turn the ignition OFF. Apply the park brake. Apply a bright light to the DRL ambient light sensor. Turn the ignition to the ON position. The headlights should turn OFF and the exterior lamps should turn OFF. If headlights do not operate as specified, repair as necessary. See HEADLIGHTS in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.