2010 Cadillac CTS Sedan AWD V6-3.6L Page 368
dimmer switch provides a voltage signal that will increase as the brightness of the lights 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 I/P lamps supply voltage circuit and the interior
backlighting components dim to the requested level.
Conditions for Running the DTC
Battery voltage must be between 9-16 V.
Conditions for Setting the DTC
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The DTC will set for the following conditions:
* The BCM detects a short to ground in the I/P dimmer switch voltage reference circuit.
* The BCM detects a short to ground in the I/P dimmer switch signal circuit.
* The BCM detects a short to ground or an open/high resistance in the BCM 1 fuse B+ circuit.
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The BCM detects a short to voltage in the I/P dimming voltage reference circuit or the vehicles system voltage exceeds the normal operating range
of 16 V.
Actions Taken When the DTC Sets
* The I/P dimmer switch will not operate.
* The I/P dimming lamps will not illuminate.
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 Verification
Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The lamps should dim and then become
full bright.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the I/P Dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 10.
瀚慖f the test lamp does not illuminate, test the ground circuit for an open/high resistance.
