Diagnostic Routine L

Diagnostic Routine L

Diagnostic Overview

The Autolamps Are On Continuously

Refer to Wiring Diagram Set 85 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

REFER to Autolamps .

REFER to Light Sensor .

DTC Fault Trigger Conditions






Visual Inspection and Diagnostic Pre-checks

- Inspect the headlamp switch for damage.

- Inspect the light sensor for damage.

Pinpoint Test

1. CHECK THE FLM (Front Lighting Control Module) HEADLAMP SWITCH PIDs (Parameter Identifications)

NOTE: Make sure the headlamp switch is aligned in the correct position when monitoring the PIDs (Parameter Identifications).

1. Ignition ON.

2. Using a scan tool, view FLM (Front Lighting Control Module) PIDs (Parameter Identifications).

3. Using a scan tool, monitor the FLM (Front Lighting Control Module) LT_SW PID (Parameter Identification) while moving the headlamp switch through all positions.

Do the headlamp switch positions agree with the PID (Parameter Identification)?








2. USE THE RECORDED DTCs (Diagnostic Trouble Codes) FROM THE BCM (Body Control Module) SELF-TEST

1. Check the recorded results from the BCM (Body Control Module) self-test.

Is DTC (Diagnostic Trouble Code) B1A85:13 or DTC (Diagnostic Trouble Code) B1A85:11 present?








3. CHECK FOR VOLTAGE TO THE LIGHT SENSOR (NO DTC (Diagnostic Trouble Code))

1. Ignition OFF.

2. Disconnect: Light Sensor.

3. Ignition ON.

4. Place the headlamp switch in the autolamps on position.

5. Measure:





Is the voltage approximately 5 volts?








4. CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC (Diagnostic Trouble Code) B1A85:13)

1. Ignition OFF.

2. Disconnect: Light Sensor.

3. Ignition ON.

4. Place the headlamp switch in the autolamps on position.

5. Measure:





Is the voltage approximately 5 volts?








5. CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO VOLTAGE

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280B.

3. Ignition ON.

4. Measure:





Is any voltage present?








6. CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. Measure:





Is the resistance less than 3 ohms?








7. CHECK THE LIGHT SENSOR GROUND CIRCUIT FOR AN OPEN

1. Measure:





Is the voltage approximately 5 volts?








8. CHECK FOR VOLTAGE TO THE LIGHT SENSOR (DTC (Diagnostic Trouble Code) B1A85:11)

1. Ignition OFF.

2. Disconnect: Light Sensor.

3. Ignition ON.

4. Place the headlamp switch in the autolamps on position.

5. Measure:





Is the voltage approximately 5 volts?








9. CHECK THE LIGHT SENSOR INPUT CIRCUIT FOR A SHORT TO GROUND

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280B.

3. Measure:





Is the resistance greater than 10,000 ohms?








10. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Disconnect and inspect all BCM (Body Control Module) connectors.

2. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

3. Reconnect the BCM (Body Control Module) connectors. Make sure they seat and latch correctly.

4. Operate the system and determine if the concern is still present.

Is the concern still present?