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DTC B2600 or B2605

Diagnostic Instructions

    • 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.

DTC Descriptors

DTC B2600 01: Left Daytime Running Lamps Control Circuit Short to Battery

DTC B2600 02: Left Daytime Running Lamps Control Circuit Short to Ground

DTC B2600 04: Left Daytime Running Lamps Control Circuit Open

DTC B2605 01: Right Daytime Running Lamps Control Circuit Short to Battery

DTC B2605 02: Right Daytime Running Lamps Control Circuit Short to Ground

DTC B2605 04: Right Daytime Running Lamps Control Circuit Open

Diagnostic Fault Information

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

Circuit/System Description

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.

Conditions for Running the DTC

    • Battery voltage must be between 9-16 V.
    • Headlamp switch in AUTO position.

Conditions for Setting the DTC

B2600 01

The BCM detects a short to voltage in the left DRL control circuit.

B2600 02

The BCM detects a short to ground in the left DRL control circuit.

B2600 04

The BCM detects an open in the left DRL control circuit.

B2605 01

The BCM detects a short to voltage in the left DRL control circuit.

B2605 02

The BCM detects a short to ground in the left DRL control circuit.

B2605 04

The BCM detects an open in the left DRL control circuit.

Action Taken When the DTC Sets

The BCM will disable the appropriate DRL control circuit.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction free ignition cycles have occurred.

Reference Information

Schematic Reference

Headlamps/Daytime Running Lamps (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Vehicle OFF, disconnect the harness connector at the appropriate daytime running lamp.
  2. Vehicle OFF, exterior lamps OFF, test for less than 5.0 Ω between the ground circuit terminal 2 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the control circuit terminal 1 and ground.
  5. Vehicle in Service Mode.
  6. Command the Dedicated Daytime Running Lamp Command ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states
  7. 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.
  8. If all circuits test normal, replace the faulty daytime running lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Headlamp Replacement : Volt → Ampera
    • Control Module References for BCM replacement, programming and setup
   


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