2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 635
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 relay via the DRL relay control circuit. When the BCM applies ground to
the DRL relay control circuit, the DRL relay coil energizes causing the relay switch contacts to close. With the DRL relay energized, voltage is
applied through the relay switch contacts, the DRL Resistor, and the DRL fuse to the left and right low beam headlamp fuses illuminating the low
beam headlamps. Any function or condition that turns the headlamps ON will cancel DRL operation. 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
The BCM detects a short to voltage in the DRL relay control circuit.
Action Taken When the DTC Sets
The BCM will disable the DRL relay 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)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (See: Lighting and Horns/Description and Operation/Exterior Lighting Systems Description
