SMU-SEC. 8A-101-REV. SYS CHK. TBL. (HEADLAMPS) & CIRCUIT. Cadillac Seville 1996

SUBJECT: SERVICE MANUAL UPDATE - SECTION 8A-101 - REVISED SYSTEM CHECK TABLE (HEADLAMPS) AND CIRCUIT OPERATION TEXT (TWILIGHT SENTINEL)

MODELS: 1996 CADILLAC CONCOURS, DEVILLE, ELDORADO, SEVILLE

THIS BULLETIN IS BEING ISSUED TO REVISE THE SYSTEM CHECK TABLE (HEADLAMPS) ON PAGES 8A-101-10, 11 OF THE SERVICE MANUAL (SEE ATTACHED). ALSO REVISED IS THE TEXT FOR CIRCUIT OPERATION (TWILIGHT SENTINEL) ON PAGE 8A-101-22 AS FOLLOWS.

CIRCUIT OPERATION

TWILIGHT SENTINEL

THE TWILIGHT SENTINEL HOLDS THE EXTERIOR LAMPS ON FOR A PERIOD OF TIME AFTER THE IGNITION SWITCH IS REMOVED FROM RUN.

WHEN THE IGNITION SWITCH IS IN RUN, THE TRANSAXLE IS OUT OF PARK, AND THE TWILIGHT PHOTOCELL INDICATES DARKNESS, THE IPC SENDS A REQUEST VIA THE CLASS 2 SERIAL DATA LINE TO THE PZM TO ACTIVATE THE LOW BEAM HEADLAMPS. THE PZM THEN APPLIES BATTERY VOLTAGE TO THE COIL OF HEADLAMP RELAY "A". THE PZM ALSO PROVIDES GROUND FOR THE COIL. THE LOW BEAM HEADLAMPS ARE THEN ACTIVATED AS PREVIOUSLY DESCRIBED WHEN ACTIVATED FROM THE HEADLAMP SWITCH. THE PARK LAMPS ARE ALSO TURNED ON.

WHEN THE TWILIGHT SENTINEL SWITCH IS ENABLED, TERMINAL D8 OF INSTRUMENT PANEL CLUSTER (IPC) CONNECTOR C3 IS GROUNDED THROUGH THE HEADLAMP SWITCH. IF THE EXTERIOR LAMPS ARE ON FROM AN AUTOMATIC TURN ON BY THE TWILIGHT SENTINEL, THE TWILIGHT SENTINEL WILL KEEP THE HEADLAMPS AND PARK LAMPS ON FOR A DRIVER DEFINED DELAY PERIOD WHEN THE IGNITION SWITCH IS TURNED OFF. ACTIVATION OF THE HEADLAMP SWITCH WILL OVERRIDE ALL TWILIGHT SENTINEL OPERATIONS.

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