Headlights - Automatic Twilight Sentinel Cadillac Fleetwood II

Description

Headlights on vehicles equipped with twilight sentinel system are controlled by either Lamp Control Module (LCM), Daytime Running Lights (DRL) Module or Central Control Module (CCM). An ambient light sensor (photocell) is mounted on top of dash to sense sunlight levels. When headlight switch is turned on, or photocell senses darkness, input circuit to control module is grounded and module applies power to exterior lighting circuit.

Operation

Twilight sentinel system operates automatically when ignition is on, headlights are off, and twilight sentinel system is on. When turned on, twilight sentinel system automatically turns on exterior lights at dusk. At daybreak, twilight sentinel system will turn exterior lights off.

Twilight sentinel system provides a 30-second delay before switching lights on or off, thus preventing system from operating under sudden ambient lighting changes, such as passing through tunnels and exposure to bright lights at night.

AIR BAG PRECAUTIONS

Observe following precautions when working on vehicles equipped with Supplemental Inflatable Restraint (SIR) air bag systems

* Before performing any instrument panel testing, diagnosis, or repair, disable SIR system by disconnecting negative battery cable and Yellow 2-pin connector at base of steering column.

1. To enable SIR system to power down, wait 20 minutes before making any repairs. System back-up power supply still retains enough voltage to deploy air bag for a short time after battery is disconnected.
2. To avoid accidental air bag deployment, avoid Yellow SIR wiring harnesses when trouble shooting, repairing, or replacing instrument panel components. All SIR wiring harnesses are Yellow.

HANDLING PRECAUTIONS

1. Discharge personal static electricity by momentarily touching metal grounding point on vehicle before touching electronic components.
2. DO NOT touch terminals on components or connectors using fingers or metal tools. When unplugging connectors, never let metal tool contact any exposed terminal.
3. Never jumper, ground, or use test probes on components or connectors unless specified in diagnosis. Always connect ground lead first.
4. DO NOT remove solid-state components from protective packaging until ready for installation. Touch packaging to ground before opening.
5. DO NOT bump or drop components. DO NOT put component on metal work bench, metal objects, or electrically operated components, such as radio, TV, or oscilloscope.

Components Possibly Damaged By ESD

1. ABS Controller.
2. Central Control Module (CCM).
3. Chime Module And Cruise Control Module.
4. Distributorless Ignition System (DIS) Module.
5. Electronic Instrument Cluster Panel (IPC).
6. Electronic Control Module (ECM) (Including PROM, CAL-PAK, Or MEM-CAL).
7. HVAC Electronic A/C-Heater Controllers And Modules.
8. Power Control Module (PCM).
9. Radio And Theft Deterrent Modules.
10. Twilight Sentinel Module Or Amplifier.

Preliminary Trouble Shooting

1. Check headlight system operation using manual switch. If all headlights operate okay manually, but twilight sentinel does not operate properly, find test with appropriate symptom. If headlights do not operate properly using manual switch, go to next step.
2. If headlight do not operate at all, check all fuses and circuit breakers. If fuses repeatedly blow, check problem circuit for short-to-ground. If any headlight is dim, check ground connections. If one headlight is inoperative, check suspect bulb. After making any repair re-check headlight system function.

Lights Do Not Automatically Turn On In Darkness

Loose connection at headlight switch or module connector. Open wiring between fusible link and headlight switch. Inoperative headlight switch or circuit breaker. Open in ground path through on-off switch of time-delay control of sentinel switch. Inoperative photocell or module.

Lights Do Not Turn Off In Daylight

Inoperative or obstructed photocell. Poor contact between photocell and socket, or socket disengaged from mounting hole. Faulty module.

Lights Do Not Turn Off After Ignition Is Off

Fuse blown. Inoperative time delay control. Open wiring. Inoperative module. Malfunctioning photocell.

Lights Do Not Stay On Proper Time Span After Ignition Is Off

Inoperative time delay control. High resistance at module connector. Short in wiring. Inoperative module.

Warning Chime Does Not Operate

Open wire in chime circuit. Inoperative door jam switch. Poor connection at headlight switch. Inoperative module. Blown fuse. Time delay control malfunction.

TESTING

TWILIGHT SENTINEL SYSTEM OPERATION TEST

Note. Unless otherwise specified, make all measurements using a digital volt-ohmmeter with an input impedance of 10 megohms.

Without DRL

1. Turn headlight switch on. Ensure headlights turn on low beam and all taillights work. Turn ignition on and activate high beams. Ensure high beams operate.
2. Turn headlights off. Ensure all exterior lights are off. Turn twilight sentinel on. Cover ambient light sensor. Headlights and taillights should come on within 20 seconds.
3. Apply a bright light to ambient light sensor. Taillights and headlights should turn off after 40 seconds. Turn headlight switch on then off. turn ignition switch off. Exterior lights should turn off after delay (3 seconds to 3 minutes delay). If headlights operate as described, system is okay.

With DRL

1. Turn ignition to run. Turn headlight switch off. Shift Transmission to "D", then to "P". Apply bright light to ambient light sensor. Rear lights and parking lights should be off and headlights should be dim.
2. Cover ambient light sensor with cardboard. Headlights and taillights should come on within 20 seconds with headlights in low beam. With ambient sensor still covered, activate high beams. High beams should operate.
3. Turn ignition switch off. All exterior lights should go off after delay (3 seconds to 3 minutes delay). If headlights operate as described, system is okay.

Lights Do Not Automatically Turn Off In Daytime

1. Verify condition. Check for Central Control Module (CCM) codes DTC 34, 35, 36, 37, 40 and 41. Repair these faults before continuing. See appropriate «TESTS W/CODES»(/cadillac/fleetwood/ii-1993-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes) article in the ENGINE PERFORMANCE Section. If fault codes are not set, go to next step. 2)Connect Tech 1 scan tester, using mass storage cartridge No. 3000003, to Data Link Connector (DLC). Turn ignition on. Select CCM DATA. Read Ambient Light Sensor (ALS) A/D counts. If A/D counts are greater than 180, go to step 4). If A/D counts are less than 180, disconnect headlight switch. If headlights go off when switch is disconnected, replace headlight switch. If headlights do not go off when switch is disconnected, go to next step.
2. If headlights remain on, disconnect Remote Control Door Lock Receiver/Theft Deterrent Module (RCDLR/TDM), located near high mounted stoplight. If headlights go off, fault is related to keyless entry system. See appropriate KEYLESS ENTRY article. If headlights remain on, repair short to ground in circuit 691 (Red/Black wire). If circuit is okay, replace CCM.
3. If A/D counts are greater than 180, remove ALS from top of instrument panel. Measure voltage at ALS connector Light Green/Black wire terminal. If voltage is not 4-5 volts, repair open in Light Green/Black wire circuit between ALS and Central Control Module (CCM). If wiring is okay, replace CCM.
4. If voltage is 4-5 volts, check resistance between ALS connector Yellow/Black wire and ground. If DVOM reads 3-4 megohms, replace ALS. If DVOM does not read 3-4 megohms, check Yellow/Black wire for open between ALS and CCM. If wire is okay, replace CCM.

Lights Do Not Automatically Go Off In Darkness

1. Check for DTC No. 34, 36 and 37. Repair these faults before continuing. See appropriate «TESTS W/CODES»(/cadillac/fleetwood/ii-1993-1996/remont/testing-diagnostics/#engine-controls-tests-wcodes) article in the ENGINE PERFORMANCE Section. If fault codes are not set, go to next step. 2)Connect Tech 1 scan tester, using mass storage cartridge No. 3000003, to Data Link Connector (DLC). Turn ignition on. Select CCM DATA. Read Ambient Light Sensor (ALS) A/D counts. If A/D counts are less than 220, go to next step. If A/D counts are greater than 220, Check for open in circuit 691 (Red/Black wire).
2. If A/D counts are less than 220, remove ALS from top of instrument panel. Measure voltage at ALS connector Light Green/Black wire terminal. If voltage is not 4-5 volts, repair open in Light Green/Black wire circuit between ALS and Central Control Module (CCM). If wiring is okay, replace CCM.
3. If voltage is 4-5 volts, check resistance between ALS connector Yellow/Black wire and ground. If DVOM reads 3-4 megohms, replace ALS. If DVOM does not read 3-4 megohms, check Yellow/Black wire for open between ALS and CCM. If wire is okay, replace CCM.

REMOVAL & INSTALLATION

Disconnect negative battery cable. Remove left sound insulator and knee bolster. Press tabs on switch assembly. Pull switch assembly from instrument panel. Unplug connectors. To install, reverse removal procedure.

TWILIGHT SENTINEL CONTROL MODULE

Note. Twilight sentinel may be also known as daytime running light module, lamp control module or central control module.

1. Twilight sentinel control is incorporated into Central Control Module (CCM). CCM is mounted on rear seat back support and is accessible from trunk.
2. If replacing CCM, have PASS-Key II(R) system reset information available before disconnecting CCM; ignition key will not be accepted otherwise. See appropriate ANTI-THEFT SYSTEM article.
3. Turn ignition off. Disconnect negative battery cable. Remove retaining nuts. Unplug 32-pin C2 connector first, then 24-pin C1 connector. Remove fastener studs from CCM and transfer to new service CCM.
4. To install, plug in C1 connector first, then C2 connector, to CCM. To complete installation, reverse removal procedure. Reconnect negative battery cable. Perform PASS-Key II(R) system reset so new CCM will accept original ignition key.

Depending on model, photocell is either mounted under left defroster grille or secured to top of instrument panel. Unsnap defroster grille. Twist photocell counterclockwise to disengage photocell and socket. Unplug connector. To install, reverse removal procedure.

WIRING DIAGRAMS

Note. For twilight sentinel system wiring diagrams, see appropriate WIRING DIAGRAMS article.

See also:
• COMPUTER RELEARN PROCEDURES
• TESTS W/CODES
• AIR BAG PRECAUTIONS