Pinpoint Test H: The Autolamps Are On Continuously
Autolamps
Pinpoint Tests
Pinpoint Test H: The Autolamps Are On Continuously
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Normal Operation
The Steering Column Control Module (SCCM) sends voltage signals to the headlamp switch through the headlamp switch input circuits (off, parking lamps, headlamps, autolamps). At any given time, the headlamp switch routes one of the input circuits to ground, indicating the headlamp switch position to the SCCM.
The SCCM sends the status of the headlamp switch position to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN).
The autolamp feature is enabled when the BCM receives a message from the SCCM indicating the headlamp switch in the AUTOLAMPS ON position.
When the BCM enables the autolamps feature, the BCM 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), the BCM provides voltage to the exterior lamps.
If the SCCM detects multiple or no active headlamp switch inputs, it sends a message to the BCM to indicate a fault with the headlamp switch input.
The BCM defaults the exterior lamps on when the BCM detects any of the following conditions:
- a fault with the light sensor input
- a message from the SCCM indicating a fault with the headlamp switch input
- the BCM loses communication with the SCCM
- DTC B1A85:11 (Ambient Light Sensor: Circuit Short To Ground) - a DTC that sets when the BCM 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 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
- SCCM
- BCM
PINPOINT TEST H: 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.
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H1 CHECK THE BCM AUTOLAMP ON REQUEST PID
NOTE: Make sure the headlamp switch is lined up in the correct position when monitoring the PID.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SCCM DataLogger .
- While placing the headlamp switch in the AUTOLAMPS ON and then OFF position, monitor the SCCM headlamp switch input PID.
- Does the PID indicate ON with the headlamp switch in the AUTOLAMPS ON position and OFF when the headlamp switch is in the OFF position
Yes
GO to H5.
No
GO to H2.
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H2 CHECK FOR A VOLTAGE SIGNAL TO THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205 .
- Measure the voltage between the headlamp switch C205-4, circuit CLF19 (VT/GN), harness side and ground.
- Is the voltage approximately 5 volts?
Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. TEST the system for normal operation.
No
GO to H3.
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H3 CHECK AUTOLAMPS REQUEST INPUT CIRCUIT FOR A SHORT TO GROUND
- Disconnect: SCCM C2414a .
- Measure the resistance between the headlamp switch C205-4, circuit CLF19 (VT/GN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to H4.
No
REPAIR circuit CLF19 (VT/GN) for a short to ground. TEST the system for normal operation.
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H4 CHECK THE AUTOLAMPS REQUEST INPUT CIRCUIT FOR AN OPEN
- Measure the resistance between the headlamp switch C205-4, circuit CLF19 (VT/GN), harness side and the SCCM C2414a-17, circuit CLF19 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to H14.
No
REPAIR circuit CLF19 (VT/GN) for an open. TEST the system for normal operation.
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H5 CHECK THE SCCM HEADLAMP SWITCH PIDs
NOTE: Make sure the headlamp switch is aligned in the correct position when monitoring the PIDs.
NOTE: Only one PID should indicate ON at each headlamp switch position.
- Enter the following diagnostic mode on the scan tool: SCCM DataLogger .
- While moving the headlamp switch through all positions, monitor the SCCM headlamp switch input (off, parking lamps and headlamps) PIDs.
- Do the headlamp switch positions agree with the PIDs (with only one PID indicating ON in each position)?
Yes
GO to H6.
No
GO to Pinpoint Test C Pinpoint Test C: The Low Beam(s) Are Always On.
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H6 USE THE RECORDED DTCs FROM THE BCM SELF-TEST
- Check the recorded results from the BCM self-test.
- Is DTC B1A85:13 or DTC B1A85:11 present?
Yes
For DTC B1A85:13, GO to H8.
For DTC B1A85:11, GO to H12.
No
GO to H7.
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H7 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (NO DTC)
- Ignition OFF.
- Disconnect: Light Sensor C286 (Manual Temperature Control) or C287 (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 C287-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C286-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 Service and Repair. TEST the system for normal operation.
No
GO to H15.
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H8 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC B1A85:13)
- Ignition OFF.
- Disconnect: Light Sensor C286 (Manual Temperature Control) or C287 (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 C287-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C286-A, circuit VLF14 (BU/BN), harness side and ground.
- Is the voltage approximately 5 volts?
Yes
GO to H11.
No
GO to H9.
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H9 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM C2280b.
- Ignition ON.
- On vehicles with automatic temperature control, measure the voltage between the light sensor C287-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C286-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 H10.
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H10 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- On vehicles with automatic temperature control, measure the resistance between the light sensor C287-2, circuit VLF14 (BU/BN), harness side and the BCM C2280b-30, circuit VLF14 (BU/BN), harness side.
- On vehicles with manual temperature control, measure the resistance between the light sensor C286-A, circuit VLF14 (BU/BN), harness side and the BCM C2280b-30, circuit VLF14 (BU/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to H15.
No
REPAIR circuit VLF14 (BU/BN) for an open. TEST the system for normal operation.
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H11 CHECK THE LIGHT SENSOR GROUND CIRCUIT FOR AN OPEN
- For vehicles with automatic temperature control, measure the voltage between the light sensor C287-2, circuit VLF14 (BU/BN), harness side and the light sensor C287-4, circuit GD184 (BK/GY or BK/YE), harness side.
- For vehicles with manual temperature control, measure the voltage between the light sensor C286-A, circuit VLF14 (BU/BN), harness side and the light sensor C286-B, circuit GD184 (BK/YE), harness side.
- Is the voltage approximately 5 volts?
Yes
INSTALL a new light sensor. REFER to Light Sensor Service and Repair. TEST the system for normal operation.
No
REPAIR circuit GD184 (BK/GY or BK/YE) for an open. TEST the system for normal operation.
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H12 CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC B1A85:11)
- Ignition OFF.
- Disconnect: Light Sensor C286 (Manual Temperature Control) or C287 (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 C287-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the voltage between the light sensor C286-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 Service and Repair. TEST the system for normal operation.
No
GO to H13.
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H13 CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM C2280b .
- On vehicles with automatic temperature control, measure the resistance between the light sensor C287-2, circuit VLF14 (BU/BN), harness side and ground.
- On vehicles with manual temperature control, measure the resistance between the light sensor C286-A, circuit VLF14 (BU/BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to H15.
No
REPAIR circuit VLF14 (BU/BN) for a short to ground. TEST the system for normal operation.
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H14 CHECK FOR CORRECT SCCM OPERATION
- Disconnect all the SCCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SCCM 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 SCCM. REFER to Steering Column Switches Service and Repair. 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.
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H15 CHECK FOR CORRECT BCM OPERATION
- Ignition OFF.
- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM 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. REFER to Multifunction Electronic Modules Service and Repair. 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.
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