2010 Cadillac CTS Sedan AWD V6-3.6L Page 504
(DDM) and front passenger door module (PDM) to apply battery voltage to the door courtesy lamps. In the event that any of these lamps were to
remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy
lamp control circuit to prevent a total battery discharge condition.
Conditions for Running the DTC
Battery voltage must be between 9-16 V.
Conditions for Setting the DTC
B2555 01
The DDM or PDM detects a short to voltage in the courtesy lamp high control circuit.
B2555 02
The DDM or PDM detects a short to ground in the courtesy lamp high control circuit.
Actions Taken When the DTC Sets
The affected door courtesy lamp will not illuminate or remain illuminated depending on the fault that is present.
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.
Diagnostic Aids
After clearing the DTC, the ignition has to be cycled ON and OFF before the inoperative courtesy lamp will operate.
Reference Information
Schematic Reference
Interior Lights Schematics (See: Diagrams/Electrical Diagrams/Lighting and Horns/System Diagram/Interior Lights 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
1. Ignition OFF, disconnect the harness connector at the appropriate front door courtesy lamp.
2. Ignition ON, test for less than 25.0 ohm between the ground circuit terminal B and ground.
瀚慖f greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance.
3. Connect a test lamp between the control circuit terminal A and the ground circuit terminal B.
4. Command the Courtesy Lamps 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 ON, test the high control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
瀚慖f the test lamp is always OFF, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal,
replace the BCM.
5. If all circuits test normal, replace the front door courtesy lamp.
