2010 Cadillac CTS Sedan AWD V6-3.6L Page 202

Diagnostic Fault Information

Circuit/System Description

The instrument panel (I/P) dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer

switch provides a voltage signal that will increase as the brightness of the light are increased and decrease as the brightness of the lights are

decreased. The body control module (BCM) provides a low reference signal and a B+ voltage reference to the I/P dimmer switch. When the I/P

dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch

signal circuit to the BCM. The BCM interprets the signal and applies the dimmed voltage to the individual accent lamps via the accent lamps

control circuit. The BCM also sends a serial data message to the driver and front passenger door control modules requesting the accent lamps on

both doors be dimmed to the requested level. The driver and front passenger door modules respond by applying the appropriate voltage for the

requested dim level to the accent lights.

Conditions for Running the DTC

* Battery voltage must be between 9-16 V.

* Park lamps ON.

Conditions for Setting the DTC

The BCM detects a short to ground in the accent lamp control circuit.

Actions Taken When the DTC Sets

The BCM will not illuminate the accent lamps supplied by the accent lamp 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

Interior Lights Dimming Schematics (See: Diagrams/Electrical Diagrams/Lighting and Horns/System Diagram/Interior Lights Dimming

Schematics)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

Interior Lighting Systems Description and Operation (See: Lighting and Horns/Description and Operation/Interior Lighting Systems Description

and Operation)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit

Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Testing

Note: Each back lighted component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the

following:

* Back lighted components the vehicle is equipped with.

Mercedes Benz