2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 670

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 670

Replacement (Cadillac) (See: Lighting and Horns/Tail Lamp/Service and Repair/Tail Lamp Replacement (Cadillac))Tail Lamp Replacement

(Tahoe, Yukon) (See: Lighting and Horns/Brake Lamp/Brake Light Bulb/Service and Repair/Tail Lamp Replacement (Tahoe/Yukon))

* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, setup, and programming

With RPO Code T4Q

DTC B2600 (With T4Q)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptor

DTC B2600 00

- Daytime Running Lamp Control Circuit

Diagnostic Fault Information

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 and 4.9 V depending on outside lighting conditions. The body control module (BCM) provides a 5 V reference signal to the ambient light

sensor. The body control module (BCM) monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for

either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. In daylight conditions,

the BCM will command the DRLs ON by applying ground to the DRL resistor via the DRL resistor control circuit. When the BCM applies ground

to the DRL resistor control circuit, the DRL signal circuits to the right and left headlamp assemblies are pulled low. The DRL signal circuits are

direct inputs to the right and left headlamp control modules. When the DRL signal circuits are provided with ground, the right and left headlamp

control modules respond by turning OFF the low beam headlamps and activating the DRLs. Any function or condition that turns the headlamps ON

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

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

Action Taken When the DTC Sets

* The Service Headlamp Assembly indicator is commanded ON.

* The BCM will disable the DRL resistor 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

Headlights/Daytime Running Lights (DRL) Schematics (See: Diagrams/Electrical Diagrams/Lighting and Horns/System

Diagram/Headlights/Daytime Running Lights (DRL) Schematics)