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| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ambient Light Sensor Signal | B2645 03 | B2645 07 | B2645 07 | -- |
Daytime Running Lamp Control - Left (T4F) | B2600 02 | B2600 04 | B2600 01 | - |
Daytime Running Lamp Control - Right (T4F) | B2605 02 | B2605 04 | B2605 01 | - |
Left Dipped Beam Headlamp Control (T4A) | B2575 02 | B2575 04 | B2575 01 | - |
Right Dipped Beam Headlamp Control (T4A) | B2699 02 | B2699 04 | B2699 01 | -- |
Ambient Light Sensor Ground | - | B2645 07 | 2 | -- |
Daytime Running Lamp Ground - Left (T4F) | -- | 2 | -- | -- |
Daytime Running Lamp Ground - Right (T4F) | -- | 2 | -- | -- |
Left Dipped Beam Ground (T4A) | -- | 1 | -- | -- |
Right Dipped Beam Ground (T4A) | -- | 1 | -- | -- |
1. Headlamps Malfunction 2. Daytime Running Lamps Malfunction | ||||
The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2-4.9 V depending on outside lighting conditions. The body control module (BCM) provides a 5 V reference signal to the ambient light sensor which is permanently grounded. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lamps (DRL) or automatic lamp control when the headlamp switch is in the AUTO position. In daylight conditions, the BCM will command the DRL ON by applying a pulse width modulated (PWM) voltage to the left and right DRL control circuits illuminating the DRL. Any function or condition that turns on the headlamps will cancel DRL operation.
| • | Battery voltage must be between 9-16 V. |
| • | Headlamp switch in AUTO position. |
The BCM detects a short to voltage in the left DRL control circuit.
The BCM detects a short to ground in the left DRL control circuit.
The BCM detects an open in the left DRL control circuit.
The BCM detects a short to voltage in the left DRL control circuit.
The BCM detects a short to ground in the left DRL control circuit.
The BCM detects an open in the left DRL control circuit.
The BCM will disable the appropriate DRL control circuit.
| • | The condition responsible for setting the DTC no longer exists. |
| • | A history DTC will clear once 100 consecutive malfunction free ignition cycles have occurred. |
Headlamps/Daytime Running Lamps (DRL) Schematics
Exterior Lighting Systems Description and Operation
Control Module References for scan tool information
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, programming and setup |
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