2010 Cadillac CTS Sedan AWD V6-3.6L Page 520
* The BCM detects a short to ground in the I/P lamps dimmer switch signal circuit.
* The BCM detects a short to ground or an open/high resistance in the BCM 7 fuse B+ circuit.
Actions Taken When the DTC Sets
The BCM will not DIM or illuminate any I/P lamps supplied by the I/P lamps dimmer switch signal 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 disconnect 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.
* Component locations on the back lighting dimming control circuit.
* Each components control and ground circuits terminals.
1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohm between the ground circuit and ground.
瀚慖f greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the Incandescent Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the
commanded states.
瀚慖f 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 BCM.
瀚慖f the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the component with the inoperative backlighting.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Refer to the appropriate replacement procedure for the component causing the condition.
* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, setup, and programming
