Pinpoint Test O: The Autolamps Are On Continuously
Autolamps
Pinpoint Test O: The Autolamps Are On Continuously
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information Electrical Diagrams.
Normal Operation
The Front Lighting Control Module (FLM) sends the status of the headlamp switch position to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN).
The autolamps feature is enabled when the BCM (Body Control Module) receives a message from the FLM (Front Lighting Control Module) indicating the headlamp switch is in the AUTOLAMPS ON position.
When the BCM (Body Control Module) enables the autolamps feature, the BCM (Body Control Module) monitors the light sensor input. The light sensor determines the amount of light based on the input received from the ambient lighting conditions. When the ambient level has reached a point determined by the internal programming of the BCM (Body Control Module), the BCM (Body Control Module) provides voltage to the exterior lamps.
The BCM (Body Control Module) defaults all of the exterior lamps on when the BCM (Body Control Module) detects any of the following conditions:
- a fault with the light sensor input
- a message from the FLM (Front Lighting Control Module) indicating a fault with the headlamp switch input
- the BCM (Body Control Module) loses communication with the FLM (Front Lighting Control Module)
- DTC B1A85:11 (Ambient Light Sensor: Circuit Short To Ground)- a DTC that sets when the BCM (Body Control Module) detects a short to ground from the light sensor input circuit.
- DTC B1A85:13 (Ambient Light Sensor: Circuit Open)- a DTC that sets when the BCM (Body Control Module) detects an open or short to voltage from the light sensor input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Light sensor
- Headlamp switch (integrated into the FLM (Front Lighting Control Module))
- BCM (Body Control Module)
PINPOINT TEST O : THE AUTOLAMPS ARE ON CONTINUOUSLY
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
O1 CHECK THE FLM (Front Lighting Control Module) HEADLAMP SWITCH PIDs
NOTE: Make sure the headlamp switch is aligned in the correct position when monitoring the PIDs.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: FLM (Front Lighting Control Module) DataLogger.
- While moving the headlamp switch through all positions, monitor the FLM (Front Lighting Control Module) headlamp switch input PID (LT_SW).
Do the headlamp switch positions agree with the PID?
Yes
GO to O2.
No
INSTALL a new FLM (Front Lighting Control Module). REFER to Front Lighting Control Module (FLM) . TEST the system for normal operation.
O2 USE THE RECORDED DTCs FROM THE BCM (Body Control Module) SELF-TEST
- Check the recorded results from the BCM (Body Control Module) self-test.
Is DTC B1A85:13 or DTC B1A85:11 present?
Yes
For DTC B1A85:13, GO to O4.
For DTC B1A85:11, GO to O8.
No
GO to O3.
O3 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (NO DTC)
- Ignition OFF.
- Disconnect: Light Sensor C287 (Manual Temperature Control) or C286 (Automatic Temperature Control).
- Ignition ON.
- Place the headlamp switch in the AUTOLAMPS ON position.
- On vehicles with automatic temperature control, measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.
Is the voltage approximately 5 volts?
Yes
INSTALL a new light sensor. REFER to Light Sensor . TEST the system for normal operation.
No
GO to O10.
O4 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC B1A85:13)
- Ignition OFF.
- Disconnect: Light Sensor C287 (Manual Temperature Control) or C286 (Automatic Temperature Control).
- Ignition ON.
- Place the headlamp switch in the AUTOLAMPS ON position.
- On vehicles with automatic temperature control, measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.
Is the voltage approximately 5 volts?
Yes
GO to O7.
No
GO to O5.
O5 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280B.
- Ignition ON.
- On vehicles with automatic temperature control, measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.
Is any voltage present?
Yes
REPAIR circuit VLF14 (BU/BN) for a short to voltage. TEST the system for normal operation.
No
GO to O6.
O6 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- On vehicles with automatic temperature control, measure the resistance between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and the BCM (Body Control Module) C2280B-30, circuit VLF14 (BU/BN), harness side.
- On vehicles with manual temperature control, measure the resistance between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and the BCM (Body Control Module) C2280B-30, circuit VLF14 (BU/BN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to O10.
No
REPAIR circuit VLF14 (BU/BN) for an open. TEST the system for normal operation.
O7 CHECK THE LIGHT SENSOR GROUND CIRCUIT FOR AN OPEN
- For vehicles with automatic temperature control, measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and the light sensor C286-4, circuit GD115 (BK/GY), harness side.
- For vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and the light sensor C287-B, circuit GD115 (BK/GY), harness side.
Is the voltage approximately 5 volts?
Yes
INSTALL a new light sensor. REFER to Light Sensor . TEST the system for normal operation.
No
REPAIR circuit GD115 (BK/GY) for an open. TEST the system for normal operation.
O8 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC B1A85:11)
- Ignition OFF.
- Disconnect: Light Sensor C287 (Manual Temperature Control) or C286 (Automatic Temperature Control).
- Ignition ON.
- Place the headlamp switch in the AUTOLAMPS ON position.
- On vehicles with automatic temperature control, measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.
Is the voltage approximately 5 volts?
Yes
INSTALL a new light sensor. REFER to Light Sensor . TEST the system for normal operation.
No
GO to O9.
O9 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280B.
- On vehicles with automatic temperature control, measure the resistance between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the resistance between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to O10.
No
REPAIR circuit VLF14 (BU/BN) for a short to ground. TEST the system for normal operation.
O10 CHECK FOR CORRECT BCM (Body Control Module) OPERATION
- Ignition OFF.
- Disconnect all the BCM (Body Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM (Body Control Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new BCM (Body Control Module). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.