Lighting Systems Cadillac DTS I

Fastener Tightening Specifications

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DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check - Vehicle will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The Use of the Diagnostic System Check - Vehicle will identify the correct procedure for diagnosing the system and where the procedure is located.

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the I/P lamps supply voltage circuit and the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

Conditions for Running the DTC

The ignition is ON.

B1395 03

The BCM detects a voltage that is lower than 9 volts on the I/P dimming voltage reference circuit.

B1395 07

The BCM detects a voltage that is greater than 14 volts on I/P dimming voltage reference circuit.

Action Taken When the DTC Sets

The I/P lamps are not illuminated.

Conditions for Clearing the DTC

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References 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 I/P lamps should dim and then become full bright.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition ON, test for B+ between the reference voltage circuit terminal 15 and ground. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM.
3. Ignition OFF, disconnect the X3 harness connector at the BCM.
4. Ignition ON, test the 12 volt reference circuit terminal 12 for a short to voltage.
5. If all circuits test normal, replace the headlamp switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage is supplied at all times to the body control module (BCM) from the 10A INT LAMPS fuse located in the rear fuse block. The BCM then applies this voltage to the following lamps

V4U Base Vehicle

1. Instrument panel (I/P) compartment lamp
2. Courtesy lamp module
3. Rear compartment lamp
4. Vanity mirror lamps

+V4U Limousine

1. I/P compartment lamp
2. Rear compartment lamp
3. Vanity mirror lamps

+V4U/B9Q Hearse

1. I/P compartment lamp
2. Overhead console lamps
3. Overhead lamp relay
4. Rear compartment lamp
5. Rear roof rail lamps
6. Vanity mirror lamps

In the event that any of these lamps were to remain illuminated for more the 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps circuit to prevent total battery discharge.

The ignition is ON.

Conditions for Setting the DTC

The BCM detects a short to ground on the inadvertent power courtesy lamp circuit.

The BCM will deactivate inadvertent power to the courtesy lamps.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, activate each inadvertent power courtesy lamp. Ignition OFF, activate each inadvertent power courtesy lamp. Lamps should remain illuminated for more the 20 minutes with the ignition switch in the OFF position. The BCM will deactivate the inadvertent power courtesy lamps circuit to prevent total battery discharge.

1. Ignition OFF, disconnect the appropriate harness connector at each component fed by the inadvertent power courtesy lamp circuit.
2. Ignition ON, with a scan tool clear the DTC.
3. Operate the vehicle within the Conditions for Running the DTC and verify the DTC does not reset. If the DTC resets, test the inadvertent power courtesy lamp circuit for a short to ground. If the circuit test normal, replace the BCM.
4. Connect each component one at a time and verify that the DTC does not reset as current. If the DTC resets, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Instrument Panel Compartment Lamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Instrument Panel Storage Compartment Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Roof Rail Rear Courtesy Lamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Roof Rail Rear Courtesy Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
5. «Vanity Mirror Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
6. «Rear Compartment Courtesy Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
7. «Relay Replacement (Attached to Wire Harness)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
8. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The fog lamps are controlled by the body control module (BCM) by inputs from the for lamp switch. When the BCM receives a fog lamps ON command, it grounds the fog lamp relay control circuit in order to energize the FOG LAMP PCB Relay. With the relay energized, battery voltage is applied through the switch side of the relay, the FOG Fuse, and the fog lamps supply voltage circuits to the fog lamps.

The ignition is ON. Park lamps must be ON and the fog lamps must be commanded ON.

This DTC will set when the BCM detects a short to voltage in the front fog lamp relay control circuit.

The BCM will deactivate the fog lamp relay for the remainder of the ignition cycle.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Schematic Reference

Fog Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, turn the park lamps ON. Press the front fog lamp switch. The front fog lamps should illuminate.

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 23 and B+.
3. Ignition ON, command the fog lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuit tests normal, replace the underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When the PRNDL is placed in the REVERSE position, a signal is sent to the body control module (BCM). The BCM then applies voltage through the backup lamps voltage supply circuit to the left and right backup lamps.

The ignition is ON. The backup lamps must be commanded ON.

The BCM detects a short to ground on the backup lamps supply voltage circuit.

The BCM will deactivate the backup lamps for the remainder of the ignition cycle.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, place the PRNDL to the REVERSE position. The backup lamps should illuminate.

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the backup lamp supply voltage circuit terminal 2 (C6) for a short to ground.
3. Ignition OFF, disconnect the harness connectors at the components listed below. Inside rearview mirror Left tail lamp assembly Right tail lamp assembly
4. Connect a test lamp between the left backup lamp supply voltage circuit terminal 1 and ground.
5. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Clear the DTC with a scan tool.
7. Reconnect each component one at a time and operate the system under the Conditions for Running the DTC. Verify the DTC does not reset as current. If the DTC resets as current, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Tail Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Inside Rearview Mirror Replacement»(/cadillac/dts/i-2005-2011/remont/mirrors/#mirror-systems)
3. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The CTSY/RF TRN fuse supplies battery voltage to the body control module (BCM). When the BCM commands the courtesy lamps ON, it applies battery voltage through the courtesy lamp relay control circuit to the coil side of the OVRHD LAMPS Relay, energizing the relay. Battery voltage from the inadvertent power courtesy lamp circuit is applied through the switch side of the relay and the courtesy lamp supply voltage circuit to the overhead console lamp, illuminating the courtesy lamp. The BCM also applies battery voltage through the courtesy lamp supply voltage circuit to the left and right roof rail courtesy lamps and the front, middle, and rear door courtesy lamps. When any door is opened, the door open switch contacts close and the BCM receives a door-open input and it will illuminate the courtesy lamps. If the BCM receives a door lock or unlock input or a rear hatch open input, it will illuminate the courtesy lamps.

Battery voltage must be between 9-16 volts.

The BCM detects a short to voltage in the courtesy lamp relay control circuit.

The BCM will deactivate the overhead lamps relay for the remainder of the ignition cycle.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition OFF, remove the OVRHD LAMPS Relay from the rear fuse block.
2. Connect a test lamp between the control circuit terminal 4 and ground.
3. Ignition ON, command the Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If 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.
4. If the circuit tests normal, test or replace the overhead lamp relay.

Component Testing

Relay Test

1. Ignition OFF, disconnect the relay.
2. Test for 70-100 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 85 30 and 86 30 and 87 85 and 87 If not the specified value, replace the relay.
4. Install a 10A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Two different inputs to the body control module (BCM) can turn ON the low beam headlamps. The headlamp switch and the ambient light sensor.

Automatic Headlamps Operation

When the ambient light sensor detects a low light condition, the BCM then applies a ground to the headlamp low beam relay control circuit. This energizes the LO BEAM PCB relay and applies voltage through the LO BEAM fuses to the headlamp assemblies.

Headlamp Switch Operation

When the headlamp switch is placed in the ON position, ground is applied to the BCM through the headlamp switch headlamps ON signal circuit. The BCM then applies a ground to the headlamp low beam relay control circuit. This energizes the LO BEAM PCB relay and applies voltage through the headlamp LO BEAM fuses to the headlamps assemblies.

The ignition is ON. The headlamps must be commanded ON by the BCM from inputs by either the headlamp switch or the ambient light sensor.

The BCM detects a short to voltage on the headlamp low beam relay control circuit while trying to energize the relay.

The BCM turns off the headlamp low beam relay control for the remainder of the ignition cycle.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, turn the headlamps ON. The headlamps should illuminate.

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 10 and B+.
3. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If the circuit tests normal, test or replace the underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) supplies a B+ reference voltage through each of the headlamp switch signal circuits to the headlamp switch. When the headlamp switch is in the AUTO position, all headlamp switch signal circuits to the BCM are open and the BCM operates in the automatic mode. When the headlamp switch is turned to the PARK position, only the park lamp switch signal circuit is pulled low signaling the BCM park lamps ON request. When the headlamp switch is turned to the HEAD position, the park lamp and headlamp switch signal circuits are both pulled low, signaling the BCM the headlamps ON request. When the headlamp switch is turned to the OFF position, only the headlamp off switch signal circuit is pulled low, signaling the BCM the lights off request.

The ignition is ON.

The BCM receives a mismatch signal between the headlamps OFF signal circuit, the headlamp switch headlamps ON signal circuit and the park lamps ON signal circuit.

The BCM disregards the headlamp switch input and defaults to automatic headlamp function.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON with the headlamp switch in the Auto position, observe the scan tool Exterior Lighting parameters listed below. All parameters should be Inactive.

1. Auto Hdlp. Disable Sw.
2. Headlamp Switch
3. Parklamp Switch

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition ON, test for B+ between the signal circuits listed below and ground. Headlamp switch headlamps ON signal terminal 1 Park lamp switch ON signal terminal 2 Headlamp switch OFF signal terminal 3 If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
3. Install a 3A fused jumper wire between the headlamp OFF signal circuit terminal 3 and ground. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the park lamp ON signal circuit terminal 2 and ground. Verify the scan tool Parklamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Connect a 3A fused jumper wire between the park lamp ON signal circuit terminal 2 and the headlamps ON signal circuit terminal 1 to ground. Verify the scan tool Headlamp Switch parameter is Active. If not the specified value, test the headlamps On signal circuit for a short to voltage or an open/high resistance. If the circuits test normal replace the BCM.
6. If all circuits test normal, replace the headlamp switch.

Component Test

Headlamp Switch

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for infinite resistance between the signal terminal 3 and the ground terminal 8 with the switch in the Auto position. If not the specified value, replace the headlamp switch.
3. Test for infinite resistance between the signal terminal 1 and the ground terminal 8 with the switch in the Auto position. If not the specified value, replace the headlamp switch.
4. Test for less than 2.0 ohms of resistance between the signal terminal 3 and the ground terminal 8 with the switch in the Off position. If not the specified value, replace the headlamp switch.
5. Test for less than 2.0 ohms of resistance between the signal terminal 1 and the ground terminal 8 with the switch in the Headlamp position. If not the specified value, replace the headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Voltage is applied at all times to the headlamp high beam relay from battery voltage. When the multifunction switch is placed in either the FTP or HIGH position, ground is applied through the signal circuits to the body control module (BCM). The BCM then applies a ground to the headlamp high beam relay control circuit. This energizes the relay and applies voltage through the HI BEAM fuses to both left and right headlamp assemblies energizing the high beam solenoids.

The ignition is ON. The high beam headlamps must be commanded ON by the multifunction switch.

The BCM detects a short to voltage on the headlamp high beam relay control circuit while trying to apply a ground to energize the relay.

The BCM turns off the headlamp high beam relay control for the remainder of the ignition cycle.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Connector End View Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, turn headlamps ON and place the turn signal/multifunction switch in the headlamp high beam position. Observe the scan tool High Beam Relay Command parameter. The reading should display On and the high beam headlamps should illuminate.

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 19 and B+.
3. Ignition ON, command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If the circuit tests normal, test or replace the underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

All Countries Except Japan, Korea, Taiwan

Voltage is applied at all times to the PRK LAMP relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch ON signal circuit to the body control module (BCM). The BCM then applies a ground to the park lamp relay control circuit. This energizes the relay and applies voltage through both PRK LAMP fuses and the park lamp supply voltage circuits illuminating the park, tail, and license lamps.

Japan, Korea, Taiwan Only

Voltage is applied at all times to the PRK LAMP relay and the RT PRK LAMP relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch signal circuit to the BCM. The BCM then applies a ground to both the park lamp relay control circuits. This energizes the relays and applies voltage through both PRK LAMP fuses and the park lamp supply voltage circuits illuminating the park, tail, and license lamps.

The ignition is ON. The park lamps must be commanded ON by the headlamp switch.

The BCM detects a short to voltage on the park lamp relay control circuit while trying to apply a ground to energize the relay.

The BCM turns off the park lamp relay control for the remainder of the ignition cycle.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, turn the headlamp switch to the park lamps ON position. Observe the scan tool Park Lamp Relay Command parameter. The reading should display On and the park lamps should illuminate.

1. Ignition OFF, remove the appropriate PRK LAMP Relay or RT PRK LAMP relay from the rear fuse block.
2. Connect a test lamp between B+ and the appropriate relay control circuit terminal listed below. PRK LAMP relay terminal 101 RT PRK LAMP relay terminal 92 - Japan, Korea, Taiwan only
3. Ignition ON, command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If the circuit tests normal, test or replace the park lamp relay.

Relay Test

1. Ignition OFF, disconnect the park lamp relay.
2. Test for 70-100 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 85 30 and 86 30 and 87 85 and 87 If not the specified value, replace the relay.
4. Install a 10A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage is applied at all times to the left front cornering lamp PCB relay which is part of the underhood fuse block. When the turn signal switch is placed in the left turn position, ground is applied through the left turn signal switch signal circuit to the body control module (BCM) The BCM then applies a ground to the left cornering lamp relay control circuit energizing the relay. With the relay energized, battery voltage is applied through the switch side of the relay, the LF CRN LAMP Fuse, and the left front cornering lamp supply voltage circuit to the left front cornering lamp.

1. The ignition must be ON.
2. The park or headlamps must be ON.
3. The left turn signal must be ON.
4. The cornering lamp must be commanded on by the BCM.

The BCM detects a short to voltage on the left cornering lamp relay control circuit while trying command the cornering lamp ON.

The BCM will deactivate the cornering lamp relay for the remainder of the ignition cycle.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between battery voltage and the control circuit terminal 3.
3. Ignition ON, command the Left Cornering Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If the circuit tests normal, replace the underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage is applied at all times to the right front cornering lamp PCB relay which is part of the underhood fuse block. When the turn signal switch is placed in the right turn position, ground is applied through the right turn signal switch signal circuit to the body control module (BCM) The BCM then applies a ground to the right cornering lamp relay control circuit energizing the relay. With the relay energized, battery voltage is applied through the switch side of the relay, the RF CRN LAMP Fuse, and the right front cornering lamp supply voltage circuit to the right front cornering lamp.

1. The ignition must be ON
2. The park or headlamps must be ON
3. The right turn signal must be ON
4. The cornering lamp must be commanded on by the BCM

The BCM detects a short to voltage on the right cornering lamp relay control circuit while trying to command the cornering lamp ON.

The BCM will deactivate the cornering lamp relay for the remainder of the ignition cycle.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between B+ and the control circuit terminal 2.
3. Ignition ON, command the Right Cornering Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If the circuit tests normal, replace the underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage is supplied at all times to the body control module (BCM) from the SWITCH DM fuse located in the rear fuse block. The BCM supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P dimming switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a variable voltage through the backlight lamp control circuits illuminating the components listed below.

1. Headlamp switch
2. HVAC control head
3. Diver information center (DIC) switch
4. Clock
5. Radio
6. Rear HVAC control
7. Steering wheel control switch

1. The ignition is ON.
2. The headlamps or park lamps ON.

The BCM detects a short to ground on the backlight lamp control circuit.

The BCM will not DIM or illuminate any backlighting supplied by the backlight lamp control circuits.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, cover the ambient light sensor. Adjust the interior lamp dimming switch from dim to full bright. The backlighting lamps should dim and then become full bright.

1. Ignition OFF, disconnect the harness connectors at all components fed by the backlight lamp control circuits listed below. Backlight lamp control terminal 18 X3 Backlight lamp control terminal 21 X6
2. Ignition ON, clear the DTC with a scan tool.
3. Operate the vehicle within the conditions for running the DTC and verify the DTC does not reset. If the DTC resets, test the control circuits for a short to ground. If the circuits test normal, replace the BCM.
4. Reconnect each component one at a time and verify that the DTC does not reset as current. If the DTC resets as current, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Driver Information Display Switch Replacement»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
2. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Auxiliary Heater and Air Conditioning Control Replacement»(/cadillac/dts/i-2005-2011/remont/automatic-hvac-system/#hvac-system-automatic)
4. «Radio Replacement»(/cadillac/dts/i-2005-2011/remont/entertainment-systems/#cellular-system-entertainment-system-and-navigation-system)
5. «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)
6. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage for the courtesy lamps is supplied at all times, from the CTSY/RF TRN Fuse located in the rear fuse block, to the body control module (BCM). When the BCM receives a signal to command the courtesy lamps ON, it then applies voltage through the courtesy lamps supply voltage circuits to the courtesy lamps listed below.

1. Courtesy Lamp Module
2. Left and right roof rail courtesy/reading lamps
3. Left and right rear door courtesy/puddle lamps
4. Overhead console lamp

1. The BCM attempts to illuminate the courtesy lamps.
2. Engine ON, the BCM attempts to illuminate the day time running lamps.
3. Ignition ON with the right turn signal switch active, the BCM attempts to illuminate the right front turn signal.

1. The BCM detects a short to ground on the courtesy lamp supply voltage circuit.
2. The BCM detects a short to ground on the right front turn signal supply voltage circuit.

The BCM will not attempt to activate courtesy lamps or the right front turn signal.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, command the Courtesy Lamps ON and OFF with a scan tool. The courtesy lamps should turn ON and OFF when changing between commanded states.

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the supply voltage circuits listed below for a short to ground. Right front turn signal lamp supply voltage terminal 5 X4 Courtesy lamp supply voltage terminal 1 X6 Courtesy lamp supply voltage terminal 5 X2
3. Ignition OFF, connect the X4 harness connector to the BCM.
4. Disconnect the harness connectors at all components fed by the supply voltage circuits listed below. Right front turn signal lamp supply voltage terminal 5 X4 Courtesy lamp supply voltage terminal 1 X6 Courtesy lamp supply voltage terminal 5 X2
5. Ignition ON, clear the DTC with a scan tool.
6. Operate the vehicle within the conditions for running the DTC and verify the DTC does not reset. If the DTC resets, test the supply voltage circuits for a short to ground. If the circuits test normal, replace the BCM.
7. Reconnect each component one at a time and verify that the DTC does not reset. If the DTC resets, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Roof Rail Rear Courtesy Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Roof Console Replacement»(/cadillac/dts/i-2005-2011/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim)
3. «High Intensity Discharge Headlamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal then applies a pulse width modulated (PWM) voltage through the LED dimming supply circuit illuminating the components listed below to the requested level.

1. Clock
2. DIC switches
3. Headlamp switch
4. HVAC control module
5. Telltale assembly info center
6. Rear HVAC module
7. Left and right rear heated seat switch indicators

The ignition is ON.

The BCM detects a short to ground on the LED dimming supply circuit.

The BCM will not attempt to illuminate the LED indicator lamps.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The LED lamps should dim and then become full bright.

1. Ignition OFF, disconnect the harness connectors at all components fed by the LED backlight dimming supply circuit terminals listed below. Terminal 25 X3 Terminal 25 X7
2. Ignition ON, clear the DTC with a scan tool.
3. Operate the vehicle within the conditions for running the DTC and verify the DTC does not reset. If the DTC resets, test the LED dimming supply circuit for a short to ground. If the circuit test normal, replace the BCM.
4. Reconnect each component one at a time and verify that the DTC does not reset as current. If the DTC resets as current, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Clock Replacement»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
3. «Auxiliary Heater and Air Conditioning Control Replacement»(/cadillac/dts/i-2005-2011/remont/automatic-hvac-system/#hvac-system-automatic)
4. «Driver Information Display Switch Replacement»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
5. «Information Center Telltale Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/collisionavoidance/#object-detection-system)
6. «Rear Seat Heater Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#seat-heating-system-seat-cooling-system)
7. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM and HVAC control module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The ambient light sensor is used to monitor outside lighting conditions. The body control module (BCM) provides a 5-volt reference signal to the ambient light sensor. The sensor is a variable resistor, it's resistance changes as outside lighting conditions change. With the headlamp switch in the AUTO position, the BCM monitors the sensor signal circuit to determine if the outside lighting conditions are correct for either daytime running lamps (DRL) or headlamp low beam operation. In daylight conditions, the BCM will command the DRLs ON. In low light conditions, the BCM will command the low beam headlamps ON.

1. The ignition is ON.
2. The headlamp switch in the AUTO position.

B2645 03

The DTC will set when the BCM detects the ambient light sensor signal voltage is below 0.196 volts.

B2645 07

The DTC will set when the BCM detects the ambient light sensor signal voltage is above 4.9 volts.

The BCM defaults to low light status and commands the low beam headlamps ON.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal C and ground. If greater than the specified range, test the low reference circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 volts. If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal D and the low reference circuit terminal C. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 volts. If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the ambient light sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ambient Light Sensor Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage, supplied by the SWITCH DM Fuse located in the rear fuse block, through the instrument panel lamp supply voltage circuits illuminating the components listed below.

1. Hazard switch
2. Ashtray lamp
3. Left middle door window switch
4. Right middle door window switch
5. Traction control switch
6. Floor shifter assembly - PRNDL lamp
7. Auxiliary HVAC control module
8. Garage door opener switch
9. Sunroof switch
10. Sunshade switch
11. Left rear door window switch
12. Left rear door heated seat switch
13. Left rear door seat lumbar switch
14. Right rear door window switch
15. Right rear door heated seat switch
16. Right rear door seat lumbar switch

1. The ignition is ON.
2. The headlamps or park lamps ON.

The BCM detects a short to ground on the instrument panel lamps supply voltage circuit.

The BCM does not attempt to illuminate the instrument panel lamps.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, cover the ambient light sensor. Vary the interior lamp dimming switch from dim to full bright. The I/P lamps should dim and then become full bright.

1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the supply voltage circuits listed below for a short to ground. Instrument panel lamp supply voltage circuit terminal 3 X2 Instrument panel lamp supply voltage circuit terminal 3 X6
3. Ignition OFF, connect the X2 harness connector at the BCM.
4. Disconnect the harness connectors at all components fed by the BCM supply voltage circuits listed below. Instrument panel lamp supply voltage circuit terminal 3 X2 Instrument panel lamp supply voltage circuit terminal 3 X6
5. Ignition ON, clear the DTC with a scan tool.
6. Operate the system within the Conditions for Running the DTC and verify the DTC does not reset. If the DTC resets, test the supply voltage circuits for a short to ground. If the circuits test normal, replace the BCM.
7. Reconnect each component one at a time and verify that the DTC does not reset. If the DTC resets, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Hazard Warning Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Ashtray Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Electronic Traction Control Switch Replacement»(/cadillac/dts/i-2005-2011/remont/anti-locktraction-control/#anti-lock-brake-system-traction-control-system-stability-control-system)
4. «Auxiliary Heater and Air Conditioning Control Replacement»(/cadillac/dts/i-2005-2011/remont/automatic-hvac-system/#hvac-system-automatic)
5. «Transmission Floor Shift Control Indicator Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
6. «Sunroof Switch Replacement»(/cadillac/dts/i-2005-2011/remont/sun-rooft-topconvertible-top/#sunroof-system)
7. «Garage Door Opener Replacement»(/cadillac/dts/i-2005-2011/remont/door-locks-anti-theft-systems/#keyless-entry-system-remote-functions)
8. «Rear Side Door Window Switch Replacement»(/cadillac/dts/i-2005-2011/remont/heated-glassdefoggers/#fixed-moveable-window-systems)
9. «Rear Seat Heater Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#seat-heating-system-seat-cooling-system)
10. «Rear Seat Lumbar Control Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#power-seat-system)
11. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage is applied at all times to the body control module (BCM) from the CHMSL/BCK-UP Fuse located in the rear fuse block. When the brake pedal is applied and the BCM receives a brake applied signal from the brake pedal position sensor (BPPS). It then applies battery voltage from the CHMSL/BCK-UP fuse through the CHMSL voltage supply circuit to the CHMSL.

1. The ignition is ON.
2. The stop lamps must be commanded ON.

The BCM detects a short to ground on the CHMSL voltage supply circuit when the stop lamps are being commanded ON.

The CHMSL does not illuminate.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition OFF, disconnect the harness connector at the CHMSL.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal A and ground.
4. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when pressing and releasing the brake pedal. If the test lamp is always ON, test the voltage supply circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the voltage supply 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, test or replace the CHMSL.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «High Mount Stop Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The instrument panel (I/P) dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the I/P lamps supply voltage circuit and the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

The ignition is ON.

1. The BCM detects a short to ground or open in the I/P dimming voltage reference circuit.
2. The BCM detects a short to ground or open in the I/P dimming signal circuit.

The I/P lamps are not illuminated.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The I/P lamps should dim and then become full bright.

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition ON, test for B+ between the reference voltage circuit terminal 15 and ground. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM.
3. Verify the scan tool Dimming Control Signal parameter is less than 0.2 volts. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM
4. Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool Dimming Control Signal parameter is greater than 2.75 volts. If less than the specified value, test the signal 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 headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) provides a 5-volt reference voltage and a low reference signal to the brake pedal position sensor (BPPS). When the brake pedal is applied, the BPPS sends a variable voltage signal, that will increase as the brake pedal is applied, through the brake apply sensor signal circuit to the BCM. In response to this signal, the BCM applies battery positive voltage to the stop lamps, center high mounted stop lamp (CHMSL), transmission control module (TCM), and engine control module (ECM). The stop lamps will not operate unless the ignition is in the ON position.

The ignition is ON.

C0277 06

The BCM detects a short to ground or open on the brake apply sensor signal circuit, or a short to ground or an open in the brake position sensor 5-volt reference circuit.

C0277 07

The BCM detects short to voltage on the brake apply sensor signal circuit.

C0277 09

The BCM detects the brake pedal position sensor reading is erroneous.

C0277 4B

The BCM detect that the brake pedal position sensor home position is not learned.

C0890 03

The BCM detects a short to ground in the brake position sensor 5-volt reference circuit.

C0890 07

The BCM detects a short to voltage in the brake position sensor 5-volt reference circuit.

1. The Service Vehicle Soon indicator is commanded ON.
2. If the DTC sets while the vehicle is running, the BCM will activate the brake lights when the vehicles transmission is not in the PARK position and the vehicle is not accelerating.
3. For DTC C0277 4B, the stop lamps may not activate at the expected brake pedal positions.

1. The condition responsible for setting the DTC no longer exists.
2. For DTC C0277 4B, a successful brake pedal position sensor calibration has been performed.
3. A DTC will not clear the current status until the next ignition cycle.
4. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

The stop lamps will not illuminate unless the ignition is in the ON position.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

C0277 06, C0277 07, and C0890 03

1. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.
2. Ignition OFF, verify that a test lamp illuminates between the low reference circuit terminal C and B+. If the test lamp does not illuminate, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the body control module (BCM).
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal A and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. Verify the scan tool BPP Sensor parameter is less than 2 counts. If greater than the specified value, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal A. Verify the scan tool BPP Sensor parameter is greater than 1000 counts. If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the brake pedal position sensor.

C0277 09

1. Replace the brake pedal position sensor.
2. Perform the scan tool BPP Sensor Calibration procedure.
3. Operate the vehicle within the Conditions for Running and Setting the DTC and verify the DTC does not reset. If the DTC resets, replace the BCM.

C0277 4B

1. Ignition ON, verify that no other brake pedal position sensor DTCs are set. If other brake pedal sensor DTCs are set, diagnosis those DTCs first.
2. Ignition ON, perform the scan tool BPP Sensor Calibration procedure. Refer to «Brake Pedal Position Sensor Calibration»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
3. Observe the scan tool BPPS Status parameter. The reading should be Learned. If not the specified value, replace the brake pedal position sensor. If the DTC resets, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Brake Pedal Position Sensor Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) provides a 5-volt reference voltage and a low reference signal to the brake pedal position sensor (BPPS). When the brake pedal is applied, the BPPS sends a variable voltage signal, that will increase as the brake pedal is applied, through the stop lamp switch signal circuit to the BCM. The BCM then applies a signal through the stop lamp switch signal circuit to the engine control module (ECM) and transmission control module (TCM).

1. The engine must be ON.
2. The brake must be applied.

The BCM detects a short to ground in the stop lamp switch signal circuit.

1. The BCM stores the DTC to memory.
2. The Service Vehicle Soon indicator is commanded ON.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, press and release the brake pedal. The stop lamps should illuminate then go out.

1. Ignition OFF, disconnect the harness connector at the TCM and the C1 harness connector at the ECM.
2. Connect a test lamp between the signal circuit terminal 42 of the TCM and ground.
3. Engine ON, press and release the brake pedal. The test lamp should turn ON and OFF when pressing and releasing the brake pedal. If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit test normal, replace the BCM. If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM.
4. Ignition OFF, connect the harness connector at the TCM.
5. Connect a test lamp between the signal circuit terminal 7 of the ECM and ground.
6. Engine ON, press and release the brake pedal. The test lamp should turn ON and OFF when pressing and releasing the brake pedal. If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the TCM
7. If all circuits test normal, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM, TCM and ECM replacement, setup and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) before using a symptom table in order to verify that all of the following conditions are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Review the system description and operation in order to familiarize yourself with the system functions. Refer to the following: «Exterior Lighting Systems Description and Operation»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) «Interior Lighting Systems Description and Operation»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the lighting system. Refer to «Checking Aftermarket Accessories»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Backup Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Cornering Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Courtesy Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Daytime Running Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
5. «Front Fog Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
6. «Hazard Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
7. «Headlamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
8. «Interior Backlighting Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
9. «Park, License, and/or Tail Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
10. «Stop Lamps Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
11. «Turn Signal Lamps and/or Indicators Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When the PRNDL is placed in the REVERSE position, a GMLAN signal is sent from the transmission control module (TCM) to the body control module (BCM). The BCM then applies voltage through the backup lamps voltage supply circuit to the tail lamp assemblies illuminating the backup lamps.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, place the PRNDL in the REVERSE position. The backup lamps should illuminate.

1. Ignition OFF, disconnect the harness connector at the appropriate tail lamp assembly.
2. Test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal listed below and ground: Domestic - terminal C Export - terminal H If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal E and ground.
4. Ignition ON, cycle the PRNDL between the PARK and REVERSE positions. The test lamp should turn ON and OFF when changing between park and reverse. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the body control module. If 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 body control module.
5. If all circuits test normal, test or replace the appropriate component.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Tail Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Inside Rearview Mirror Replacement»(/cadillac/dts/i-2005-2011/remont/mirrors/#mirror-systems)
3. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Battery voltage is applied at all times to both front cornering lamp PCB relays which are an internal part of the underhood fuse block. When the turn signal switch is activated, ground is applied through the turn signal switch signal circuit to the body control module (BCM) The BCM then applies a ground to the appropriate cornering lamp relay control circuit energizing the relay. With the relay energized, battery voltage is applied through the switch side of the relay, the LT or RT CRN LAMP Fuse, and the cornering lamp supply voltage circuit to the cornering lamp.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, operate the left and right turn signal and observe the related cornering lamp. The cornering lamp should illuminate as long as the turn signal is ON.

1. Ignition ON, park or headlamps ON, place the turn signal switch in the direction of the inoperative cornering lamp.
2. With a test lamp connected to ground, probe each of the test points on the appropriate CRN LAMP Fuse. The test lamp should illuminate at one or both of the fuse test points. If the test lamp does not illuminate at either test point or remains illuminated at all times with turn signal OFF, refer to the «Corner Lamp PCB Relay Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the test lamp illuminates, refer to the «Cornering Lamp Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .

Corner Lamp PCB Relay Circuit Test

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between battery voltage and the appropriate control circuit listed below. Left cornering lamp relay control terminal 3 Right cornering lamp relay control terminal 2
3. Ignition ON, park or headlamps ON, operate the turn signal switch ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If the circuit tests normal, replace the underhood fuse block.

Cornering Lamp Circuit Test

1. Ignition OFF, disconnect the harness connector at the inoperative fog/cornering lamp.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for and open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal B and ground.
4. Ignition ON, park or headlamps ON, operate the turn signal switch ON and OFF, The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the underhood fuse block.
5. If all circuits test normal, test or replace the cornering lamp bulb.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Cornering Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Cornering Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
4. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) receives battery voltage from the CTSY/RF TRN fuse in order to supply power to the courtesy lamps. The BCM applies this voltage to the courtesy lamps through the courtesy lamp supply voltage circuits. When any door is opened, the door open switch contacts close and the BCM receives a door-open signal. If the BCM receives a door lock or unlock signal, the BCM will activate the courtesy lamp supply voltage circuit, providing battery voltage to the dome lamps. The BCM also sends a serial data message to the front door control modules to illuminate the door courtesy lamps. The courtesy lamps can be manually activated by placing the interior lamp switch in the DOME position. For more detailed information concerning courtesy lamp operation refer to Interior Lighting Systems Description and Operation .

The BCM receives battery voltage from the INT LAMPS fuse in order to supply power to the inadvertent courtesy lamps. Inadvertent power courtesy lamp feature provides a similar function for the interior lamps as a retained accessory power feature. The BCM will energize the courtesy lamps supply voltage circuit when the BCM is in the active state (awake). When the inadvertent power courtesy lamps supply voltage circuit is energized, it supplies voltage to all the interior lights listed below. The BCM will continue to supply voltage to the interior lamps after the ignition is turned OFF so that the interior lamps may be operated.

1. Overhead Console Courtesy/Reading Lamps
2. Courtesy Lamp Module
3. Roof Rail Courtesy/Reading Lamps
4. Vanity Mirror Lamps
5. I/P Compartment Lamp
6. Rear Compartment Courtesy Lamp

In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position and no BCM input activity, the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition.

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Observe the scan tool Driver Door Switch, Driver Door Open Sw. parameter while opening and closing the driver door. The reading should change between Open and Closed. If the Driver Door Open Sw. parameter does not change between Open and Closed, refer to «Door Open Switch Test-Front»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Observe the scan tool Passenger Door Switch, Passenger Door Open Sw. parameter while opening and closing the front passenger door. The reading should change between Open and Closed. If the Passenger Door Open Sw. parameter does not change between Open and Closed, refer to «Door Open Switch Test-Front»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
3. Observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while opening and closing each rear door one at a time. The reading should change between Door Open and Door Closed. If the Ctsy. Lamp Actv. Reason parameter does not change between Door Open and Door Closed, refer to «Door Open Switch Test-Rear»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
4. Ignition ON and all doors closed, observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while turning the dome lamp switch ON and OFF. The reading should change between OFF and MANUAL. If the Ctsy. Lamp Actv. Reason parameter does not change between OFF and MANUAL, refer to «Dome Lamp Switch Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
5. If all scan tool parameters test normal, refer to the appropriate diagnostic procedure listed below. Courtesy/Reading Lamps Circuit Test - with Courtesy Lamp Module Front Door Courtesy Lamp Circuit Test Courtesy Lamp Circuit Test - w/o Courtesy Lamp Module Inadvertent Power Courtesy Lamps Circuit Test Overhead Console Courtesy/Reading Lamp Circuit Test - Limo/Hearse Roof Rail Courtesy/Reading Lamp Circuit Test - Limo/Hearse

Door Open Switch Test - Front

1. Ignition OFF, disconnect the harness connector at the inoperative door latch assembly.
2. Ignition OFF and the appropriate door control module fuse removed, test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal listed below and ground. Driver Front Door Latch Assembly terminal 4 Passenger Front Door Latch Assembly terminal 1 If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the door control module
3. Ignition ON, verify the appropriate scan tool Door Switch Door Open Sw. parameter is Inactive. If not the specified value, test the appropriate signal circuit listed below for a short to ground. If the circuit tests normal, replace the appropriate door control module. Driver Front Door Latch Assembly terminal 1 Passenger Front Door Latch Assembly terminal 4
4. Install a 3A fused jumper wire between the appropriate signal circuit terminal and ground. Verify the related scan tool Door Switch Door Open Sw. parameter is Open. Driver Front Door Latch Assembly terminal 1 Passenger Front Door Latch Assembly terminal 4 If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door control module.
5. If all circuits test normal, test or replace the inoperative door lock assembly.

Door Open Switch Test - Rear or Middle

1. Ignition OFF, disconnect the harness connector at the appropriate rear door lock assembly.
2. Test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal and ground. Left Rear Door Lock terminal 4 Left Middle Door Lock terminal 4 Right Rear Door Lock terminal 1 Right Middle Door Lock terminal 1 If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, all doors closed, verify the scan tool BCM Ctsy. Lamp Actv. Reason. parameter is Door Closed. If not the specified value, test the appropriate signal circuit for a short to ground. If the circuit tests normal, replace the BCM. Left Rear Door Lock terminal 1 Left Middle Door Lock terminal 1 Right Rear Door Lock terminal 4 Right Middle Door Lock terminal 4
4. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the scan tool BCM Ctsy. Lamp Actv. Reason parameter is Door Open. Left Rear Door Lock terminal 1 Left Middle Door Lock terminal 1 Right Rear Door Lock terminal 4 Right Middle Door Lock terminal 4 If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the door lock assembly.

Dome Lamp Switch Test

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, all doors closed, verify the scan tool Ctsy. Lamp Actv. Reason parameter is OFF or Door Closed. If not the specified value, test the signal circuit terminal 12 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal 12 and ground. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is MANUAL. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the headlamp switch.

Courtesy/Reading Lamps Circuit Test - with Courtesy Lamp Module

1. Ignition OFF, disconnect the X3, X4 harness connectors at the BCM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminals listed below and ground. B+ terminal 2 X3 B+ terminal 2 X4 If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the related courtesy lamp supply voltage circuits for a short to ground.
3. Ignition OFF, connect the harness connectors at the BCM.
4. Disconnect the harness connector at the courtesy lamp module.
5. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal 7 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
6. Ignition ON, verify that a test lamp illuminates between the inadvertent power courtesy lamp circuit terminal 8 and ground. If the test lamp does not illuminate, test the inadvertent power circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Door OPEN, verify that a test lamp illuminates between the courtesy lamp supply voltage circuit terminal 6 and ground. If the test lamp does not illuminate, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
8. Disconnect the harness connector at the inoperative courtesy lamp.
9. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit test normal, replace the courtesy lamp module.
10. Verify that a test lamp illuminates between the inadvertent power courtesy lamp circuit terminal A and ground. If the test lamp does not illuminate, test the inadvertent power circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the courtesy lamp module.
11. Door OPEN, verify that a test lamp illuminates between the courtesy lamp supply voltage circuit terminal C and ground. If the test lamp does not illuminate, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the courtesy lamp module.
12. If all circuits test normal, test or replace the courtesy lamp.

Front Door Courtesy Lamp Circuit Test

1. Ignition OFF, disconnect the harness connector at the appropriate door courtesy lamp.
2. Ignition OFF and the appropriate door control module fuse removed, test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the appropriate door control module.
3. Connect a test lamp between the supply voltage circuit terminal A and the ground circuit terminal B.
4. Ignition ON, command the appropriate Door Switch Puddle/Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the appropriate door control module. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate door control module.
5. If all circuits test normal, test or replace the door courtesy lamp.

Courtesy Lamp Circuit Test - w/o Courtesy Lamp Module

1. Ignition OFF, disconnect the harness connector at the inoperative courtesy lamp.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal A and ground.
4. Ignition ON, command the Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the supply voltage 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, test or replace the inoperative courtesy lamp.

Inadvertent Power Courtesy Lamps Circuit Test

1. Ignition OFF, disconnect the X3 harness connector at the BCM.
2. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the inadvertent power courtesy lamp circuits for a short to ground.
3. Ignition OFF, connect the harness connector at the BCM.
4. Disconnect the harness connector at the inoperative lamp.
5. Test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
6. Ignition ON, verify that a test lamp illuminates between the inadvertent power courtesy lamp circuit terminal A and ground. If the test lamp does not illuminate, test the inadvertent power courtesy lamp circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the inoperative lamp.

Overhead Console Courtesy/Reading Lamp Circuit Test - Limo/Hearse

1. Ignition OFF, disconnect the X3, X4 harness connectors at the BCM.
2. Verify that a test lamp illuminates between the B+ circuit terminals listed below and ground. B+ terminal 2 X3 B+ terminal 2 X4 If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the related courtesy lamp supply voltage circuits for a short to ground.
3. Ignition OFF, connect the harness connectors at the BCM.
4. Disconnect the harness connector at the overhead console lamp.
5. Test for less than 5.0 ohms of resistance between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
6. Verify that a test lamp illuminates between the inadvertent power courtesy lamp circuit terminal C and ground. If the test lamp does not illuminate, test the inadvertent power circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Remove the OVRHD LAMPS LIMO Relay from the rear fuse block.
8. Ignition ON, verify that a test lamp does not illuminate between the supply voltage circuit terminal 1 and ground. If the test lamp illuminates, test the supply voltage circuit for a short to voltage.
9. Test for less than 5.0 ohms of resistance between the ground circuit terminal 3 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
10. Verify that a test lamp illuminates between the inadvertent power courtesy lamp circuit terminal 5 and ground. If the test lamp does not illuminate, test the inadvertent power circuit for an open/high resistance.
11. Connect the harness connector at the overhead console lamp.
12. Connect a 3A fused jumper wire between the relay inadvertent power circuit terminal 5 and the supply voltage circuit terminal 1. Verify the overhead lamp courtesy lamp is illuminated. If the courtesy lamp does not illuminate, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the overhead courtesy lamp.
13. Connect a test lamp between the relay control circuit terminal 4 and ground.
14. Ignition ON, command the Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
15. If all circuits test normal, test or replace the overhead lamp relay.

Roof Rail Courtesy/Reading Lamp Circuit Test - Limo/Hearse

1. Ignition OFF, disconnect the X3, X4 harness connectors at the BCM.
2. Verify that a test lamp illuminates between the B+ circuit terminals listed below and ground. B+ terminal 2 X3 B+ terminal 2 X4 If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the related courtesy lamp supply voltage circuits for a short to ground.
3. Ignition OFF, connect the harness connectors at the BCM.
4. Disconnect the harness connector at the inoperative roof rail courtesy/reading lamp.
5. Test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
6. Door open, verify that a test lamp illuminates between the supply voltage circuit terminal A and ground. If the test lamp does not illuminate, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Verify that a test lamp illuminates between the inadvertent power circuit terminal C and ground. If the test lamp does not illuminate, test the inadvertent power circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
8. If all circuits test normal, test or replace the inoperative roof rail reading lamp.

Relay Test

1. Ignition OFF, disconnect the relay.
2. Test for 70-100 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 85 30 and 86 30 and 87 85 and 87 If not the specified value, replace the relay.
4. Install a 10A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87. If greater than the specified range, replace the relay.

Door Open Switch Test

1. Ignition OFF, remove the appropriate door lock actuator.
2. Test for infinite resistance between the appropriate signal and low reference terminals listed below with the switch in the open position. Driver door - signal terminal 1 and low reference terminal 4 Passenger door - signal terminal 4 and low reference terminal 1 Left rear door - signal terminal 1 and ground terminal 4 Right rear door - signal terminal 4 and ground terminal 1 If not the specified value, replace the appropriate door lock actuator.
3. Test for less than 2 ohms between the appropriate signal and ground terminals listed below with the switch in the closed position. Driver door - signal terminal 1 and low reference terminal 4 Passenger door - signal terminal 4 and lo reference terminal 1 Left rear door - signal terminal 1 and ground terminal 4 Right rear door - signal terminal 4 and ground terminal 1 If greater than the specified range, replace the appropriate door lock actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Interior Lamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems__interior-lamp-switch-replacement)
3. «Door Courtesy Lamp and Reflector Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Instrument Panel Compartment Lamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
5. «Instrument Panel Storage Compartment Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
6. «Roof Rail Rear Courtesy Lamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
7. «Roof Rail Rear Courtesy Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
8. «Vanity Mirror Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
9. «Rear Compartment Courtesy Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
10. «Relay Replacement (Attached to Wire Harness)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
11. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM and front door module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The ambient light sensor is a light sensitive transistor that varies the voltage signal to the body control module (BCM) based on outside lighting conditions. When the ambient light sensor indicates daytime conditions with engine running, the BCM, will then apply battery voltage through the front turn signal lamp supply voltage circuits illuminating the left and right front turn lamps. Any function or condition that turns the headlamps ON will cancel DRL operation.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition ON, verify that the left and right front turn signals operate. If not refer to «Turn Signal Lamps and/or Indicators Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Ignition ON, observe the scan tool Ambient Light Status parameter while carefully supplying sufficient light to simulate daylight conditions to the ambient light sensor for more than 30 seconds. The reading should be Day.
3. Engine running in daylight conditions with the headlamp switch in the Auto position, the front turn signal lamps should illuminate as daytime running lamps.

1. Carefully supplying sufficient light to simulate daylight conditions to the ambient light sensor for more than 30 seconds.
2. Ignition ON, observe the scan tool Ambient Light Status parameter. The reading should be Day. If not the specified value, replace the ambient light sensor. If the specified value, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ambient Light Sensor Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) controls the fog lamps based on inputs from the fog lamp switch. When the fog lamp switch is pressed, a ground path is provided on the front fog lamp switch signal circuit to the BCM, indicating the front fog lamps ON command. In response to this signal, the BCM grounds the fog lamp relay control circuit energizing the FOG LAMP PCB Relay. With the fog lamp relay energized, battery voltage is applied through the FOG Fuse and the fog lamp supply voltage circuits illuminating the front fog lamps.

When a fog lamp request is seen by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the fog lamp indicator be illuminated.

Schematic Reference

Fog Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Observe the scan tool Front Fog Lamps Switch parameter while pressing and releasing the fog lamp switch. The parameter should cycle between Active and Inactive. If the parameter does cycle between the specified values, refer to «Fog Lamp Switch Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Ignition ON, with a test lamp connected to ground, probe each of the test points on the FOG Fuse while commanding the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF at one or both of the fuse test points when changing between commanded states. If the test lamp is always OFF, or remains always ON, refer to «Fog Lamp PCB Relay Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the test lamp turns ON and OFF, refer to «Fog Lamps Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. With the fog lamps ON, verify the fog lamp indicator is illuminated on the IPC. If the indicator does not illuminate, refer to «Front Fog Lamp Indicator Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .

Fog Lamp Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Front Fog Lamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal 6 and the ground circuit terminal 8. Verify the scan tool Front Fog Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the headlamp switch.

Fog Lamp PCB Relay Circuit Test

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 23 and B+.
3. Ignition ON, command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, replace the underhood fuse block.

Fog Lamps Circuit Test

1. Ignition OFF, disconnect the harness connector at the inoperative fog lamp.
2. Test for less than 5.0 ohms of resistance between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal C and the ground circuit terminal A.
4. Ignition ON, command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
5. If all circuits test normal, test or replace the inoperative fog lamp bulb.

Front Fog Lamp Indicator Test

1. Ignition ON, with a scan tool perform the display test for the instrument panel cluster (IPC) and observe the front fog lamp indicator. If the front fog lamp indicator illuminates during the test, replace the BCM. If the front fog lamp indicator does not illuminate during the test or remains illuminated at all times, replace the IPC.

Headlamp Switch

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for infinite resistance between the signal circuit terminal 6 and the ground circuit terminal 8 with the switch in the open position. If not the specified value, replace the headlamp switch.
3. Test for less than 2.0 ohms of resistance between the signal circuit terminal 6 and the ground circuit terminal 8 with the switch in the closed position. If greater than the specified range, replace the headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Front Fog Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
4. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) controls the hazard lamps based on inputs from the hazard switch. With the hazard switch closed, a ground path is provided on the hazards switch signal circuit, indicating a hazard lamp request. When this request is seen, the BCM will pulse the turn signal lamp supply voltage circuits, illuminating the turn signal lamps.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition ON, individually operate both the left and right turn signals. All applicable lamps should flash when in each turn signal position. If any of the lamps do not flash, refer to «Turn Signal Lamps and/or Indicators Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Observe the scan tool Hazard Lamp Switch parameter while cycling the hazard switch. The parameter should change between Active and Inactive. If the parameter does not cycle between the specified values, refer to «Circuit/System Testing»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
3. Press the hazard switch. All applicable lamps should flash. If one or more lamps do not flash, replace the BCM.

1. Ignition OFF, disconnect the harness connector at the hazard switch.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Hazard Lamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal C and the ground circuit terminal B. Verify the scan tool Hazard Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the hazard switch.

Hazard Switch

1. Ignition OFF, disconnect the harness connector at the hazard switch.
2. Test for infinite resistance between the signal circuit terminal C and the ground circuit terminal B with the switch in the open position. If not the specified value, replace the hazard switch.
3. Test for less than 2.0 ohms of resistance between the signal circuit terminal C and the ground circuit terminal B with the switch in the closed position. If greater than the specified range, replace the hazard switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Hazard Warning Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category

The vehicle headlamps are controlled by the body control module (BCM) based on inputs from the headlamp switch and the turn signal/multifunction switch. The headlamp switch has four positions: Off, Auto, Park, and Headlamps. The default headlamp switch position is Auto, in which the BCM uses the ambient light sensor to determine when headlamps are needed. The Off portion of the headlamp switch is a momentary switch which overrides the automatic headlamps and will turn off the vehicle headlamps. When in the Off position, the headlamp switch grounds the headlamp switch headlamps off signal circuit, prompting the BCM to turn off all exterior lamps. The Park position of the headlamp switch will only illuminate the vehicle parking lamps. The Headlamp position of the headlamp switch will illuminate both the parking lamps, as well has the headlamps. With the headlamp switch in the Headlamp position, the headlamp switch headlamps on signal circuit is grounded, prompting the BCM to turn on the headlamps, regardless of other factors such as ambient light.

The headlamp high beams are controlled through the flash to pass switch and the headlamp dimmer switch, both located in the turn signal/multifunction switch. The flash to pass switch is a momentary type switch, designed to illuminate the high beams as long as the switch is held. With the switch closed, the flash to pass switch signal circuit is grounded, prompting the BCM to turn on the high beam lamps. The headlamp dimmer switch allows the operator to select between full time high or low beam operation. Unlike the flash to pass switch, it is not a momentary switch. When the headlamp dimmer switch is in the high beam position, the headlamp dimmer switch high beam signal circuit is grounded. This prompts the BCM to turn on the high beam lamps.

The BCM controls the headlamps based on the inputs explained above. When a low beam request is received, the BCM grounds the headlamp low beam relay control circuit. This energizes the coil in the LO BEAM PCB Relay, causing the relay switch to close. This then applies B+ through the LT LO BEAM and RT LO BEAM fuses, the headlamp supply voltage circuits to the headlamp ballasts, illuminating the headlamps. When a high beam request is received, the BCM grounds the headlamp high beam relay control circuit. This energizes the coil in the HIGH BEAM PCB Relay, causing the relay switch to close. Battery voltage is then applied through both HI BEAM fuses and the high beam headlamp supply voltage circuits to the headlamp high beam solenoids. The solenoids then open the low beam shields to fully expose the headlamp bulbs for high beam operation.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition ON, observe the scan tool Auto Hdlp. Disable Sw. parameter while cycling the headlamp switch between the Auto and Off positions. The parameter should cycle between Active and Inactive. If the parameter does not cycle between the specified values, refer to «Headlamp Switch Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Observe the scan tool Headlamp Switch parameter while cycling the headlamp switch between the Auto and Head position. The parameter should cycle between Active and Inactive. If the parameter does not cycle between the specified values, refer to «Headlamp Switch Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
3. With the headlamps ON, observe the scan tool Flash to Pass Switch parameter while pulling and releasing the flash to pass switch. The parameter should cycle between Active and Inactive. If the parameter does not cycle between the specified values, refer to «Turn Signal/Multifunction Switch Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
4. With the headlamps ON, observe the scan tool High Beam Select Switch parameter while switching the headlamp dimmer switch between the low and high beam positions. The parameter should cycle between Active and Inactive. If the parameter does not cycle between the specified values, refer to «Turn Signal/Multifunction Switch Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
5. Ignition ON, with a test lamp connected to ground, probe each of the test points on either LO BEAM Fuse while commanding the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF at one or both of the fuse test points when changing between commanded states. If the test lamp is always OFF, or remains always ON, refer to «Low Beam PCB Relay Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the test lamp turns ON and OFF, refer to «Headlamps Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
6. Ignition ON, with a test lamp connected to ground, probe each of the test points on either HI BEAM Fuse while commanding the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF at one or both of the fuse test points when changing between commanded states. If the test lamp is always OFF, or remains always ON, refer to «High Beam PCB Relay Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the test lamp turns ON and OFF, refer to «High Beam Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
7. Ignition ON, headlamps ON, observe the high beam indicator on the IPC while cycling the high beam dimmer switch ON and OFF. The indicator should turn ON and OFF when changing between commanded states. If the indicator is always OFF or remains always ON, replace the IPC.

Headlamp Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Headlamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Inactive. If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Headlamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the headlamp switch.

Turn Signal/Multifunction Switch Circuit Test

1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal D and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Flash to Pass Switch parameter is Inactive. If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool High Beam Select Switch parameter is Inactive. If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Flash to Pass Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool High Beam Select Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Low Beam PCB Relay Circuit Test

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 10 and B+.
3. Ignition ON, command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, replace the underhood fuse block.

Headlamps Circuit Test

1. Disconnect the harness connector at the inoperative headlamp assembly.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal F and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal E and ground.
4. Ignition ON, command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
5. If all circuits test normal, test or replace the inoperative headlamp bulb.

High Beam PCB Relay Circuit Test

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between B+ and the control circuit terminal 19.
3. Ignition ON, command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, replace the underhood fuse block.

High Beam Circuit Test

1. Disconnect the harness connector at the inoperative headlamp assembly.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal F and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the supply voltage circuit terminal D and ground.
4. Ignition ON, command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
5. If all circuits test normal, test or replace the inoperative headlamp assembly.

Headlamp Switch

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for infinite resistance between the signal terminal 3 and the ground terminal 8 with the switch in the Auto position. If not the specified value, replace the headlamp switch.
3. Test for infinite resistance between the signal terminal 1 and the ground terminal 8 with the switch in the Auto position. If not the specified value, replace the headlamp switch.
4. Test for less than 2.0 ohms of resistance between the signal terminal 3 and the ground terminal 8 with the switch in the Off position. If not the specified value, replace the headlamp switch.
5. Test for less than 2.0 ohms of resistance between the signal terminal 1 and the ground terminal 8 with the switch in the Headlamp position. If not the specified value, replace the headlamp switch.

Turn Signal/Multifunction Switch

1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
2. Test for infinite resistance between the signal terminal A and the ground terminal D with the flash to pass switch in the open position. If not the specified value, replace the turn signal/multifunction switch.
3. Test for infinite resistance between the signal terminal E and the ground terminal D with the headlamp dimmer switch in the low beam position. If not the specified value, replace the turn signal/multifunction switch.
4. Test for less than 2.0 ohms of resistance between the signal terminal A and the ground terminal D with the flash to pass switch in the closed position. If not the specified value, replace the turn signal/multifunction switch.
5. Test for less than 2.0 ohms of resistance between the signal terminal E and the ground terminal D with the headlamp dimmer switch in the high beam position. If not the specified value, replace the turn signal/multifunction switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Headlamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Turn Signal Multifunction Switch Replacement»(/cadillac/dts/i-2005-2011/remont/steering-column-switches/#steering-wheel-steering-column)
4. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
5. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the instrument panel lamp supply voltage circuit and the backlight lamp control circuit illuminating the lamps on these dimming circuits. At the same time the BCM sends a serial data message requesting the front door modules to illuminate the door switches. For more detailed information concerning interior lamp operation refer to Interior Lighting Systems Description and Operation .

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition ON, observe the driver door switch while commanding the Driver Door Switch Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states. If the backlighting does not turn On and OFF or remains always ON, replace the driver door switch.
2. Ignition ON, observe the driver heated and cooled seat switch while commanding the Driver Door Switch Non-Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states. If the backlighting does not turn On and OFF or remains always ON, refer to «Front Door Switch Backlighting Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
3. Ignition ON, observe the passenger door switch while commanding the Passenger Door Switch Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states. If the backlighting does not turn On and OFF or always remains ON, replace the passenger door switch.
4. Ignition ON, observe the passenger heated and cooled seat switch while commanding the Passenger Door Switch Non-Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states. If the backlighting does not turn On and OFF or remains always ON, refer to «Front Door Switch Backlighting Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
5. Ignition ON, observe the scan tool BCM Dimming Control Signal parameter while operating the dimmer switch from high to low. The reading should change from a high percent to a low percent as the switch is rotated. If the reading does not change, refer to «Dimmer Switch Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the scan tool dimmer control operates normal, refer to «Interior Backlighting Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .

Dimmer Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 volts. If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
4. Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 15 and ground. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 volts. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp switch.

Interior Backlighting Circuit Test

1. Ignition OFF, disconnect the harness connector at the component with the inoperative backlighting.
2. Test for less than 5.0 ohms between the appropriate ground circuit terminal listed below and ground. Headlamp Switch terminal 8 Hazard Switch terminal B Ashtray Lamp terminal B HVAC Control Module terminal 11 X1 Driver Information Display Switch terminal 6 Clock terminal 2 Radio terminal 8 X1 Left Middle Door Window Switch terminal 1 - Limo Right Middle Door Window Switch terminal 1 - Limo Traction Control Switch terminal A Floor Shifter Assembly terminal D X2 Garage Door Opener Transmitter terminal 3 Sunshade Switch terminal A Sunroof Switch terminal 5 Left Rear Door Window Switch terminal 1 Left Rear Heated Seat Switch terminal J Left Rear Seat Lumbar Switch terminal E Right Rear Door Window Switch terminal 1 Right Rear Heated Seat Switch terminal J Right Rear Seat Lumbar Switch terminal E Auxiliary HVAC Control Module terminal 8 Right Steering Wheel Control Switch terminal 1 Left Steering Wheel Control Switch terminal 8 If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the appropriate supply voltage circuit terminal listed below and ground. Incandescent Dimming Hazard Switch terminal A Ashtray Lamp terminal A Traction Control Switch terminal D Floor Shifter Assembly terminal C X2 Garage Door Opener Transmitter terminal 2 Sunshade Switch terminal D Sunroof Switch terminal 3 Left Rear Door Window Switch terminal 2 Left Rear Heated Seat Switch terminal F Left Rear Seat Lumbar Switch terminal D Right Rear Door Window Switch terminal 2 Right Rear Heated Seat Switch terminal F Right Rear Seat Lumbar Switch terminal D Left Middle Door Window Switch terminal 2 - Limo Right Middle Door Window Switch terminal 2 - Limo LED Dimming Headlamp Switch terminal 7 HVAC Control Module terminal 2 X3 Driver Information Display Switch terminal 5 Clock terminal 3 Radio terminal 7 X1 Auxiliary HVAC Control Module terminal 10 Right Steering Wheel Control Switch terminal 2 Left Steering Wheel Control Switch terminal 6
4. Ignition ON, command the appropriate Incandescent Dimming or LED Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM If the test lamp is always ON, test the supply voltage 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.

Front Door Switch Backlighting Circuit Test

1. Ignition OFF, disconnect the X4 harness connector at the appropriate driver or front passenger door control module.
2. Connect a 3A fused jumper wire between the low reference circuit terminal 4 and ground.
3. Connect a test lamp between the indicator supply voltage circuit terminal 13 and B+. The heated and cooled seat switch backlighting should illuminate. If the switch backlighting does not illuminate, replace the heated and cooled seat switch.
4. If the switch backlighting tests normal, replace the door control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Hazard Warning Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Ashtray Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Transmission Floor Shift Control Indicator Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
5. «Driver Information Display Switch Replacement»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
6. «Electronic Traction Control Switch Replacement»(/cadillac/dts/i-2005-2011/remont/anti-locktraction-control/#anti-lock-brake-system-traction-control-system-stability-control-system)
7. «Sunroof Switch Replacement»(/cadillac/dts/i-2005-2011/remont/sun-rooft-topconvertible-top/#sunroof-system)
8. «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)
9. «Door Lock and Side Window Switch Replacement - Driver Side»(/cadillac/dts/i-2005-2011/remont/door-locks-anti-theft-systems/#door-lock-systems-door-handles)
10. «Driver Seat Adjuster Memory Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#power-seat-system)
11. «Rear Side Door Window Switch Replacement»(/cadillac/dts/i-2005-2011/remont/heated-glassdefoggers/#fixed-moveable-window-systems)
12. «Rear Seat Lumbar Control Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#power-seat-system)
13. «Heated and Cooled Seat Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#seat-heating-system-seat-cooling-system)
14. «Rear Seat Heater Switch Replacement»(/cadillac/dts/i-2005-2011/remont/seats/#seat-heating-system-seat-cooling-system)
15. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM, HVAC control module, Auxiliary HVAC control module, IPC, or Radio replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Ground is provided to the headlamp switch through the switch ground circuit and G304. With the headlamp switch in the ON position, the headlamps ON signal circuit from the body control module (BCM) is pulled low indicating the headlamps ON request. In response to this signal, the BCM will energize either the high or low beam relay illuminating the headlamps. At the same time when the high beam headlamps are ON, the BCM sends a message via GMLAN serial data to the instrument panel cluster (IPC) requesting the IPC to illuminate the high beam indicator. Anytime the headlamps are ON and the ignition is OFF or the driver door is opened, the BCM will also request the IPC to turn on the LIGHTS ON INDICATOR located in the driver information center (DIC).

This diagnostic procedure assumes that the headlamps operate as described in Exterior Lighting Systems Description and Operation .

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, with a scan tool perform the display test for the IPC and observe the lights on indicator.

1. If the lights on indicator does not illuminate during the test or remains illuminated at all times, replace the IPC.
2. If the lights on indicator illuminates during the test, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM or IPC replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The vehicle park, license, and tail lamps are controlled by the body control module (BCM) based on an input from the headlamp switch. The headlamp switch has 4 positions: Off, Auto, Park, and Headlamps. The default headlamp switch position is Auto, in which the BCM uses the ambient light sensor to determine when exterior lamps are needed. The Off portion of the headlamp switch is a momentary switch which overrides the automatic lamps and will turn off the vehicle lamps. The Park position of the headlamp switch will only illuminate the vehicle parking lamps. The Headlamp position of the headlamp switch will illuminate both the parking lamps, as well has the headlamps. With the headlamp switch in the Park position, the park lamp switch on signal circuit is grounded, prompting the BCM to turn on the exterior lamps, regardless of other factors such as ambient light.

When a park lamp request is received, the BCM grounds the park lamp relay control circuit. This energizes the coil in the PARK LP PCB relay, causing the relay switch to close. Battery voltage is then applied through the LT PARK and RT PARK LAMP fuses and the park lamp supply voltage circuits illuminating the exterior lamps.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Parklamp Switch parameter while cycling the headlamp switch between the Park and Off positions. The parameter should cycle between Active and Inactive. If the parameter does not cycle between the specified values, refer to «Headlamp Switch Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Ignition ON, command the Parking Lamps ON and OFF with a scan tool. Verify the park, license, and tail lamps turn ON and OFF between commanded states. If any of the parking lamps are always OFF or remain always ON, refer to the appropriate «Park, License, and/or Tail Lamps Circuit Test - All Countries Except Japan, Korea, Taiwan or Japan, Korea, Taiwan Only»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If just the license lamps on an Japan, Korean, Taiwan vehicle are always OFF, refer to «License Lamps Circuit Test - Japan, Korea, Taiwan Only»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .

Headlamp Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Parklamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Parklamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the headlamp switch.

Park, License, and/or Tail Lamps Circuit Test - All Countries Except Japan, Korea, Taiwan

1. Ignition OFF, disconnect the PRK LAMP relay from the rear fuse block.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 104 and ground. If the test lamp illuminates, test the control circuits for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 102 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 100 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Connect a test lamp between the B+ circuit terminal 102 and the control circuit terminal 101.
6. Command the parking lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Disconnect the harness connector at the inoperative lamp.
8. Ignition OFF, test for less than 5.0 ohms between the appropriate ground circuit terminal listed below and ground: Front park and marker lamp terminal A Tail lamp terminal C License lamp terminal B Middle park lamp terminal B (V4U) Rear park lamp terminal B (V4U or B9Q) If greater than the specified range, test the ground circuit for an open/high resistance.
9. Connect a test lamp between the inoperative lamp control circuit terminal listed below and ground: Front park and marker lamp terminal B Tail lamp terminal F License lamp terminal A Middle park lamp terminal A (V4U) Rear park lamp terminal A (V4U or B9Q)
10. Connect a 3A fused jumper wire between the B+ circuit terminal 100 and the control circuit terminal 104. Verify the test lamp is illuminated. If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the bulb or lamp assembly.
11. If all circuits test normal, test or replace the park lamp relay.

Park, and/or Tail Lamps Circuit Test - Japan, Korea, Taiwan Only

1. Ignition OFF, disconnect the appropriate PRK LAMP relay or the RT PRK LAMP relay from the rear fuse block.
2. Ignition ON, verify that a test lamp does not illuminate between the appropriate control circuit terminal listed below and ground: PRK LAMP relay terminal 104 RT PRK LAMP relay terminal 94 If the test lamp illuminates, test the control circuits for a short to voltage.
3. Verify that a test lamp illuminates between the appropriate B+ circuit terminal listed below and ground: PRK LAMP relay terminal 102 RT PRK LAMP relay terminal 90 If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the appropriate B+ circuit terminal listed below and ground: PRK LAMP relay terminal 100 RT PRK LAMP relay terminal 93 If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Connect a test lamp between the appropriate B+ circuit terminal and the control circuit terminal listed below: PRK LAMP relay terminal 102 and terminal 101 RT PRK LAMP relay terminal 93 and terminal 92
6. Command the parking lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Disconnect the harness connector at the inoperative lamp.
8. Ignition OFF, test for less than 5.0 ohms between the appropriate ground circuit listed below and ground: Front park and marker lamp terminal A Tail lamp terminal H License lamp terminal B Middle park lamp terminal B (V4U) Rear park lamp terminal B (V4U or B9Q) Position lamp terminal A (T72) Position lamp terminal H (T84) If greater than the specified range, test the ground circuit for an open/high resistance.
9. Connect a test lamp between the inoperative lamp control circuit listed below and ground: Front park and marker lamp terminal B Tail lamp terminal F License lamp terminal A Middle park lamp terminal A (V4U) Rear park lamp terminal A (V4U or B9Q) Position lamp terminal G
10. Connect a 3A fused jumper wire between the appropriate relay B+ circuit terminal and the control circuit terminal listed below. Verify the test lamp is illuminated. PRK LAMP relay terminal 100 and terminal 104 RT PRK LAMP relay terminal 90 and terminal 94 If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the bulb or the lamp assembly.
11. If all circuits test normal, test or replace the park lamp relay.

License Lamp Circuit Test - Japan, Korea, Taiwan Only

1. Ignition OFF, disconnect the EXP LIC LAMP relay from the rear fuse block.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal 9 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 10 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
4. Park lamps ON, verify that a test lamp illuminates between the control circuit terminal 6 and ground. If the test lamp does not illuminate, test the control circuit for an open/high resistance.
5. Park lamps ON, verify that a test lamp illuminates between the control circuit terminal 8 and ground. If the test lamp does not illuminate, test the control circuit for an open/high resistance.
6. Ignition OFF, disconnect the harness connector at the inoperative license lamp.
7. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
8. Connect a test lamp between the control circuit terminal A and ground.
9. Connect a 3A fused jumper wire between the relay control circuit terminal 10 and B+. The test lamp should illuminate. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the bulb or the lamp assembly.
10. If all circuits test normal, test or replace the EXP LIC LAMP relay.

Headlamp Switch

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for less than 2.0 ohms between the signal terminal 2 and the ground terminal 8 with the switch in the Park position. If not the specified value, replace the headlamp switch.
3. Test for less than 2.0 ohms between the signal terminal 2 and the ground terminal 8 with the switch in the Headlamp position. If not the specified value, replace the headlamp switch.

Relay Test

1. Ignition OFF, disconnect the relay.
2. Test for 70-100 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 85 30 and 86 30 and 87 85 and 87 If not the specified value, replace the relay.
4. Install a 10A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «High Intensity Discharge Headlamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Headlamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Front Side Marker Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
5. «Park/Turn Signal Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
6. «Rear License Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
7. «Tail Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
8. «Relay Replacement (Attached to Wire Harness)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
9. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, center high mounted stop lamp (CHMSL), transmission control module (TCM), and engine control module (ECM). Ground for the left tail lamp assembly and CHMSL is provided by G402 and ground for the right tail lamp assembly is provided by G403.

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to stop lamp relay coil control circuit, transmission control module (TCM), engine control module (ECM), and center high mounted stop lamp (CHMSL). When the stop lamp relay receives battery voltage from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage from the STOP LAMPS EXP fuse to illuminate the rear stop lamps and trailer stop lamps. Ground for the left tail lamp assembly and CHMSL is provided by G402 and ground for the right tail lamp assembly is provided by G403.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Stop Lamps Circuit Test - All Countries Except Japan, Korea, Taiwan

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify a test lamp illuminates between the terminals listed below and ground: B+ terminal 1 B+ terminal 3 B+ terminal 4 If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the B+ circuit and the respective stop lamp circuits for a short to ground.
3. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.
4. Verify that a test lamp illuminates between the low reference circuit terminal C and B+. If the test lamp does not illuminate, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
5. Ignition OFF, disconnect harness connector at the inoperative stop/turn lamp.
6. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal C and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect a test lamp between the control circuit terminal B and ground.
8. Ignition ON, command the appropriate LR or RR Turn Signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If 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.
9. If all circuits test normal, replace the inoperative stop/turn signal bulb or lamp assembly.

Stop Lamps Circuit Test - Japan, Korea, Taiwan Only

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify a test lamp illuminates between the B+ terminals listed below and ground. B+ terminal 1 B+ terminal 3 B+ terminal 4 If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the B+ circuit and the respective stop lamp circuits for a short to ground.
3. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.
4. Verify that a test lamp illuminates between the low reference circuit terminal C and B+. If the test lamp does not illuminate, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
5. Ignition OFF, disconnect the STOP LAMP EXP relay from the rear fuse block.
6. Test for less than 5 ohms between the ground circuit terminal 9 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Ignition ON, verify a test lamp does not illuminate between the control circuit terminal 6 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
8. Verify that a test lamp illuminates between the B+ circuit terminal 10 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
9. Connect a test lamp between the control circuit terminal 8 and the ground circuit terminal 9.
10. Ignition ON, apply and release the brake pedal. The test lamp should turn ON and OFF as the brake pedal is applied and released. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If 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.
11. Disconnect the harness connector at the inoperative stop lamp.
12. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal H and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
13. Connect a test lamp between the control circuit terminal B and ground.
14. Connect a 3A fused jumper wire between the stop lamp relay B+ circuit terminal 10 and the control circuit terminal 6. The test lamp should illuminate. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the bulb.
15. If all circuits test normal, test or replace the stop lamp relay.

High Mounted Stop Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the CHMSL.
2. Ignition OFF, test for less than 5.0 ohm between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal A and the ground circuit terminal B.
4. Ignition ON, apply and release the brake pedal. The test lamp should turn ON and OFF as the brake pedal is applied and released. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If 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.
5. If all circuits test normal, replace the CHMSL.

Relay Test

1. Ignition OFF, disconnect the relay.
2. Test for 70-100 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 85 30 and 86 30 and 87 85 and 87 If not the specified value, replace the relay.
4. Install a 10A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Brake Pedal Position Sensor Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «High Mount Stop Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Tail Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Relay Replacement (Attached to Wire Harness)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
5. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Ground is applied at all times to the turn signal/multifunction switch from G300. The turn signal lamps may only be activated with the ignition switch in the ON position. The body control module (BCM) controls the vehicle turn signals based on inputs from the turn signal/multifunction switch. With the turn signal/multifunction switch in either the left or right turn position, a ground is applied through the turn signal switch signal circuit to the BCM indicating a turn signal request. When the specific request is seen, the BCM then applies a pulsating voltage through the front and rear turn signal supply voltage circuits illuminating the turn signal lamps. At the same time, the BCM sends a GMLAN serial date message requesting the door module to illuminate the outside rearview mirror turn signal by applying a low reference to the ground side of the mirror turn signal lamp.

When a turn signal request is seen by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Left and Right Turn Signal Switch parameters while cycling the turn signal switch between the left and right positions. The readings should toggle between Active and Inactive. If the readings do not change between the commanded states, refer to «Turn Signal/Multifunction Switch Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
2. Observe the left and right turn signal lamps while activating the turn signals. The front and rear turn signal lamps and the outside rearview mirror indicators should illuminate and flash when turned ON. If the front or rear turn signal lamps are inoperative, refer to the «Turn Signal Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the front turn signals operate, but the outside rearview mirror turn signal is inoperative, refer to the «Outside Rearview Mirror Turn Signal Circuit Test»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
3. Ignition ON, observe the left turn signal lamps and turn signal indicator on the IPC while activating the left turn signals. The left turn signal lamps and indicators should illuminate and flash when turned ON. If the turn signal indicator is inoperative, refer to «Turn Signal Indicators Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the left turn signal lamps and indictors illuminate but flash in a rapid manner, refer to «Tail Lamp Outage Detection Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
4. Ignition ON, observe the right turn signal lamps and turn signal indicator on the IPC while activating the right turn signals. The right turn signal lamps and indicator should illuminate and flash when turned ON. If the turn signal indicator is inoperative, refer to «Turn Signal Indicators Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) . If the right turn signal lamps and indictor illuminate but flash in a rapid manner, refer to «Tail Lamp Outage Detection Malfunction»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .

Turn Signal/Multifunction Switch Circuit Test.

1. Ignition OFF, disconnect the X3 harness connector at the turn signal/multifunction switch.
2. Test for less than 5.0 ohms between the ground circuit terminal G and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive. If not the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Right Turn Signal Switch parameter is Inactive. If not the specified value, test the signal circuit terminal H for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal F and the ground circuit terminal G. Verify the scan tool Left Turn Signal Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3A fused jumper wire between the signal circuit terminal H and the ground circuit terminal G. Verify the scan tool Right Turn Signal Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Turn Signal Circuit Test.

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify a test lamp illuminates between the following B+ terminals and ground: B+ terminal 1 B+ terminal 2 B+ terminal 3 If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the B+ circuit and the respective turn signal circuits for a short to ground.
3. Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
4. Test for less than 5.0 ohms between the appropriate ground circuit terminal listed below and ground: Front headlamp assembly terminal A (and T72) Front headlamp assembly terminal H (T84) Tail lamp assembly terminal C - All Countries Except Japan, Korea, Taiwan Tail lamp assembly terminal H - Japan, Korea, Taiwan Only Repeater lamp terminal B - Japan, Korea, Taiwan Only If greater than the specified range, test the ground circuit for an open/high resistance.
5. Connect a test lamp between the appropriate control circuit terminal listed below and the ground: Front headlamp assembly terminal C Rear tail lamp assembly terminal B - All Countries Except Japan, Korea, Taiwan Rear tail lamp assembly terminal G - Japan, Korea, Taiwan Only Repeater lamp terminal A - Japan, Korea, Taiwan Only
6. Ignition ON, command the inoperative turn signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If 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.
7. If all circuits test normal, test or replace the appropriate turn signal bulb.

Outside Rearview Mirror Turn Signal Circuit Test

1. Ignition OFF, disconnect the X1 harness connector at the inoperative outside rearview mirror.
2. Connect a test lamp between the low reference circuit terminal 2 and B+.
3. Ignition ON, command the appropriate LF or RF Turn Signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the low reference circuit for a short to ground. If the circuit tests normal, replace the door module. If the test lamp is always OFF, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door module.
4. Connect a test lamp between the control circuit terminal 1 and ground.
5. Ignition ON, command the appropriate LF or RF Turn Signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the test lamp is always OFF, test the control circuit for an open/high resistance.
6. If all circuits test normal, test or replace the outside rearview mirror lamp bulb.

Tail Lamp Outage Detection Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate rear tail lamp assembly.
2. Ignition ON, test for B+ between the signal circuit terminal D and ground. If less than B+, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
3. Ignition ON, connect a test lamp between the signal circuit terminal D and ground. The test lamp should not illuminate. If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, test or replace the tail lamp assembly.

Turn Signal Indicators Malfunction

Ignition ON, with a scan tool perform the display test for the instrument panel cluster (IPC) and observe the turn signal lamp indicators.

1. If the turn signal lamp indicators illuminate during the test, replace the BCM.
2. If the turn signal lamp indicators do not illuminate during the test or remain illuminated at all times, replace the IPC.

Turn Signal/Multifunction Switch

1. Ignition OFF, disconnect the X3 harness connector at the turn signal/multifunction switch.
2. Test for infinite resistance between the following signal circuit terminals and the ground circuit terminal E with the switch in the neutral position: Signal terminal F Signal terminal H If not the specified value, replace the turn signal/multifunction switch.
3. Test for less than 2.0 ohms between the signal circuit terminal D and the ground circuit terminal E with the switch in the left turn position. If greater than the specified range, replace the turn signal/multifunction switch.
4. Test for less than 2.0 ohms between the signal circuit terminal F and the ground circuit terminal E with the switch in the left turn position. If greater than the specified range, replace the turn signal/multifunction switch.

Tail Lamp Assembly

1. Ignition OFF, disconnect the harness connector at the appropriate rear tail lamp assembly.
2. Test for infinite resistance between the appropriate outage detection signal terminal and the ground terminal listed below: Signal terminal D and ground terminal C - All Countries Except Japan, Korea, Taiwan Signal terminal D and ground terminal H - Japan, Korea, Taiwan Only

1. If not the specified value, replace the tail lamp assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Turn Signal Multifunction Switch Replacement»(/cadillac/dts/i-2005-2011/remont/steering-column-switches/#steering-wheel-steering-column)
2. «Park/Turn Signal Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
3. «Tail Lamp Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
4. «Park/Turn Signal Lamp Bulb Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
5. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or IPC replacement, setup, and programming

Repair Instructions

Note. System does not use a Brake/stop lamp switch. System uses a brake pedal position sensor. This sensor input is used to determine brake application and to turn on brake/stop lamps.

Calibration Criteria

The brake pedal position sensor (BPPS) receives a low reference signal and a 10-volt reference signal from the body control module (BCM). Whenever the brake pedal is applied, the BPPS applies a variable voltage signal to the BCM through the stop lamp switch signal circuit. BPPS calibration must be performed after the BPPS or BCM have been serviced. The calibration procedure will set the BPPS home value. This value is used by the BCM to determine the action of the driver applying the brake system and to provide this information to the vehicle subsystems via the class 2 communication bus.

Calibration Procedure

1. Turn ON the ignition, with the engine OFF.
2. Install a scan tool. Select the proper vehicle and options.
3. Navigate to the BCM menu.
4. Select Module Setup menu item.
5. Select the BPPS calibration procedure and follow the directions displayed on the screen.

Scheme 21

Scheme 22

Interior Lamp Switch Replacement

Scheme 23

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Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

Scheme 30

Scheme 31

Scheme 32

Scheme 33

Removal Procedure

1. Open the vanity cover.
2. Using a thin-bladed tool, insert the edge of the tool under the lamp lens.
3. Carefully snap the lamp lens out of its retaining slots.
4. Remove the bulb.

Installation Procedure

1. Insert the bulb.
2. Install the lens into the retaining slots.
3. Close the vanity cover.

1. Remove the console center trim plate. Refer to «Front Floor Console Trim Plate Replacement»(/cadillac/dts/i-2005-2011/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
2. Rotate the shift indicator lamp socket (1) counterclockwise in order to release the lamp and socket (1) from the shifter assembly.
3. Remove the lamp and socket (1) from the shifter assembly.
4. Remove then shift indicator lamp (1) from the lamp socket.

1. Install the shift indicator lamp (1) to the lamp socket.
2. Install the lamp and socket to the shifter assembly.
3. Rotate the shift indicator lamp socket clockwise.
4. Install the console center trim plate. Refer to «Front Floor Console Trim Plate Replacement»(/cadillac/dts/i-2005-2011/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .

Scheme 34

Scheme 35

Scheme 36

Headlamp Aiming

1. The vehicle has a visual optical headlamp aiming system. The aim has been preset at the factory and should need no further adjustment. If the vehicle is damaged in an accident, the headlamp aim may be affected and adjustment may be necessary. Re-aim the headlamps as described in the following procedure.
2. The vehicle should be properly prepared as follows: The vehicle should be placed so the headlamps are 7.6 m (25 ft) from a light colored wall or other flat surface. The vehicle must have all 4 tires on a level surface which is level all the way to the wall or other flat surface. The vehicle should be placed so it is perpendicular to the wall or other flat surface. The vehicle should not have any snow, ice, or mud on it. The vehicle should be fully assembled and all other work stopped while headlamp aiming is being performed. The vehicle should be normally loaded with a full tank of fuel and one person or 75 kg (160 lb) sitting on the drivers seat. The tires should be properly inflated. The spare tire is in its original location in the vehicle.

Headlamp aiming is done with the vehicles low-beam headlamps. The high-beam headlamps will be correctly aimed if the low-beam headlamps are aimed properly. To adjust the vertical aim, do the following

1. Open the hood.
2. Find the center line running through the lens of the headlamp.
3. Measure the distance from the ground to the center line running through the lens of the headlamp. Record the distance.
4. At the wall or other flat surface, measure from the ground upward the recorded distance from step 5 and mark it.
5. Draw or tape a horizontal line the width of the vehicle at the wall or other flat surface where it was marked.
6. Turn ON the low-beam headlamps and place a piece of cardboard or equivalent in front of the headlamp not being aimed. This should allow only the beam of light from the headlamp being aimed to be seen on the flat surface.
7. Locate the vertical headlamp aiming screws, which are under the hood near each headlamp assembly. The adjustment screw can be turned with a phillips screwdriver.
8. Turn the vertical aiming screw until the headlamp beam is aimed to the horizontal tape line. If you turn it clockwise, it will raise the beam and if you turn it counterclockwise, it will lower the beam. The top edge of the cut-off should be positioned at the bottom edge of the horizontal tape line.
9. Repeat for the opposite headlamp.

Scheme 37

Fog Lamp Aiming

Proper road illumination and safety require the fog lamps to be aimed. The front fog lamp aim should be checked when a new front fog lamp assembly is installed, or if any service repairs have been performed to the vehicle which disturb the front fog lamp mounting or the vehicle ride height.

There are no horizontal adjustments for aiming the front fog lamp assemblies on this vehicle.

1. To ensure accurate vertical front fog lamp aiming, first perform the following steps to prepare the vehicle. Make sure that all the components are in place on the vehicle, the tires are properly inflated, and there is not any mud or snow clinging to the vehicle. Stop all other operations of work on the vehicle. Make sure the fuel level is 1/2 full or more. Jounce the vehicle to settle the suspension, (without Electronic Level Control). Place the vehicle on a level surface 7.6 m (25 ft) from the target screen. Measure the distance from the floor to the center of the fog lamp (5). Using this measurement, mark the horizontal centerline of the fog lamp (1) on the target screen directly in front of the vehicle. Start the vehicle in order to level the suspension.
2. Turn the front fog lamps ON.
3. Through the small circular opening in the front corner of the wheel liner below the fog lamp, access the fog lamp vertical adjuster screw.
4. Turn the fog lamp screw in order to adjust the lamp up or down until the top edge of the high intensity zone on the screen is 102 mm (4 in) below the horizontal centerline (1).
5. Turn OFF the front fog lamps.

Scheme 38

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Scheme 45

Scheme 46

Description & Operation

Note. System does not use a Brake/stop lamp switch. System uses a brake pedal position sensor. This sensor input is used to determine brake application and to turn on brake/stop lamps.

The exterior lighting system consists of the following lamps

1. The headlamps
2. The daytime running lamps (DRL)
3. The front fog lamps
4. The park, tail and marker lamps
5. The exterior courtesy lamps
6. The turn signal/hazard lamps
7. The side repeater lamps (w/ T72 or T84)
8. The stop lamps
9. The backup lamps
10. The cargo lamps
11. The clearance lamps

Headlamp Operation

The low beam headlamps may be turned ON in 3 different ways

1. When the headlamp switch in the HEAD position for normal operations
2. When the headlamp switch is in the AUTO position, for automatic lamp control (ALC)
3. When the headlamp switch is placed in the AUTO position, with the windshield wipers ON in daylight conditions, after a 6 second delay

Headlamps ON/OFF operation is determined by the position of the headlamp switch and controlled by the body control module (BCM). When the headlamp switch is in the AUTO position, the BCM determines headlamps ON/OFF by the voltage signal from the ambient light sensor.

High Intensity Discharge (HID) Low Beam Headlamps

High intensity discharge (HID) headlamps do not have filaments like the traditional headlamp bulbs. Instead a ballast and an arc tube is used.

When the headlamp switch is placed in the HEAD position, ground from G304 is applied through the headlamps ON signal circuit to the body control module (BCM). In response to this signal, the BCM applies ground to the headlamp low beam relay control circuit energizing the LO BEAM PCB Relay. With the relay energized, battery voltage is applied through the switched side of the relay, the LT and RT LO BEAM fuses, and the supply voltage circuits to a ballast located in each headlamp assembly. The ballast is used to increase the input voltage into a higher voltage in order to create an arc between the electrodes in the arc tube illuminating the headlamp. Ground for the left and right headlamps is provided at G104.

High Beam Headlamps

The high beam headlamps for this vehicle does not use separate high beam bulbs. Instead it uses a high beam solenoid with a shutter to re-direct the low beam headlamps for high beam use

When the headlamp dimmer switch is placed in the high beam position, ground from G300 is applied through the dimmer switch and the headlamp dimmer switch signal circuit to the BCM signaling the headlamp high beam request. In response to this signal, the BCM applies ground through the high beam relay control circuit energizing the HIGH BEAM PCB Relay. With the high beam relay energized, battery voltage is applied through the switch side of the relay, the left and right high beam fuses, and the high beam supply voltage circuits to the headlamp high beam solenoids re-directing the low beams for high beam operation. At the same time the BCM sends a GMLAN serial data message to the instrument panel cluster (IPC) requesting the IPC to illuminate the high beam indicator. Ground for the left and right headlamps is provided at G104.

Run Up of the HID Lamp

Each ballast requires higher amperage in order to ensure normal startup and run up of the lamp. Run up is the term used to describe the extra power level given to the bulb (arc tube). The input current during the steady state operation is lower than the start up amperage. After the lamp receives the strike from the starter and the arc is established, the ballast uses its operating voltage in order to provide the run up power needed to keep the lamp on. The lamp rapidly increases in intensity from a dim glow to a very high-intensity, bright light called a steady state. A high watt power level is necessary in order to bring the lamp to a steady state. Within 2 seconds of the arc being established in the bulb, 70 percent of steady state is complete. Within 30 seconds, 100 percent of the steady state is complete.

When to Change the HID Bulb (arc tube)

Bulb failure, end of life occurs when the bulb gets older and becomes unstable. The bulb may begin shutting itself OFF sporadically and unpredictably at first, perhaps only once during a 24 hour period. When the bulb begins shutting itself off occasionally, the ballast will automatically turn the bulb back on again within 0.5 seconds. The ballast will re-strike the bulb so quickly that the bulb may not appear to have shut OFF. As the bulb ages, the bulb may begin to shut OFF more frequently, eventually over 30 times per minute. When the bulb begins to shut off more frequently, the ballast receives excessive, repetitive current input. Repetitive and excessive restarts or re-strikes, without time for the ballast to cool down, will permanently damage the ballast. As a safeguard, when repetitive re-strikes are detected, the ballast will not attempt to re-strike the lamp. The ballast then shuts down and the bulb goes out.

The following symptoms are noticeable signs of bulb failure

1. Flickering light caused in the early stages of bulb failure
2. Lights go out caused when the ballast detects excessive, repetitive bulb re-strike
3. Color change-The lamp may change to a dim pink glow.

Input power to the ballast must be terminated in order to reset the ballasts fault circuitry. In order to terminate the input power to the ballast, turn the lights OFF and back ON again. Turning the lights OFF and back ON again resets all of the fault circuitry within the ballast until the next occurrence of excessive, repetitive bulb re-strikes. When excessive, repetitive bulb re-strikes occur, replace the starter/arc tube assembly. The ballast will begin the start-up process when the starter/arc tube assembly is replaced. Repeatedly resetting the input power can overheat the internal components and cause permanent damage to the ballast. Allow a few minutes of cool-down time in between reset attempts.

Bulb failures are often sporadic at first, and difficult to repeat. Bulb failure can be determined if the problem progressively gets worse over the next 100 hours of operation.

Light Color

HID headlamps have a different color rating than regular headlamps. The range of white light that is acceptable is broad when compared to halogens. Therefore, some variation in headlight coloring between the right and left headlamp will be normal. One HID at the end of the normal range may appear considerably different in color from one at the other end of the range. A difference in color is normal. Replace the arc tube only if the arc tube is determined to be at the bulb failure stage.

Daytime Running Lamps (DRL)

The front turn signal lamps are used for DRL operation. The DRLs will operate only when the engine is running and the headlamp switch is in the AUTO position. When the DRLs are ON, no other exterior lamps such as the parking lamps, tail lamps, etc. will be ON. Also, the instrument panel will not be illuminated.

DRL operation is determined by the ambient light sensor and the controlled by the body control module (BCM). The ambient light sensor is a light-sensitive transistor used to monitor outside lighting conditions. The BCM provides a 5-volt reference signal to the sensor while ground is provided at G300. The sensor will vary this voltage signal between 0.2 and 4.9 volts depending on outside lighting conditions. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either DRL or headlamp operation. When the BCM determines the conditions are met for DRL operation, it turns ON the front turn signal lamps in a steady non-flashing mode. Any function or condition that turns on the headlamps will cancel DRL operation.

When the BCM detects low light conditions, it will turn OFF the daytime running lamps and turn ON the low beam headlamps as described above in Low Beam Headlamp Operation. The BCM will also turn ON the low beam headlamps in daylight conditions when the windshield wipers are turned ON.

Flash to Pass (FTP)

When the low beam headlamps are ON and turn signal/multifunction switch handle is pulled toward the driver, ground from G300 is applied through the FTP switch and the flash to pass switch signal circuit to the BCM signaling the flash to pass request. The BCM then turns ON the high beam headlamps as described above, until the turn signal/multifunction switch handle is released. If the low beam headlamps were ON during FTP operation, they will remain ON.

IntelliBeam Intelligent High-Beam Headlamp Control System

IntelliBeam is an enhancement to your vehicles headlamp system. Using a digital light sensor on the rearview mirror, the system will turn the vehicles high beam headlamps ON and OFF according to surrounding traffic conditions. The IntelliBeam system will turn ON the high-beam headlamps when it is dark enough, there is no other traffic present, and the IntelliBeam system is enabled. When the conditions are met, the inside rearview mirror will send a GMLAN serial data message to the BCM requesting high beam headlamp operation.

Driving with IntelliBeam

IntelliBeam will only activate the high-beams when driving over 32 km/h (20 mph). The high beam headlamps will remain ON, under the automatic control of IntelliBeam, until any of the following situations occur

1. The system detects an approaching vehicles headlamps.
2. The system detects a preceding vehicles tail lamps.
3. The outside light is bright enough that the high-beam headlamps are not required.
4. The vehicles speed drops below 24 km/h (15 mph).
5. The headlamp stalk is moved forward to the high-beam position or the flash-to-pass feature issued. See when either of these conditions occur, the IntelliBeam feature will be disabled and the IntelliBeam light in the mirror will turn OFF until the high-beam stalk is returned to the neutral position.
6. If IntelliBeam was using low-beams prior to this action, the IntelliBeam feature will be temporarily disabled until the stalk is returned to the neutral position.
7. The exterior lamp control is turned to any setting except AUTO. When this occurs, IntelliBeam will be disabled until the control is turned back to the AUTO position.
8. The IntelliBeam system is turned OFF at the inside rearview mirror.

The high beam headlamps may need to manually disabled or canceled by turning the low beam headlamps ON, if any of the above conditions exist.

Disabling & Resetting IntelliBeam at the Rearview Mirror

IntelliBeam can be disabled by using the controls on the inside rearview mirror.

AUTO (On/Off)

To disable the system, press this button on the inside rearview mirror. The IntelliBeam indicator will turn OFF and then will not come back ON until the IntelliBeam button is pressed again.

Stalk Disable

When IntelliBeam has turned ON the high-beams, pull or push the high-beam stalk. This will disable IntelliBeam. The IntelliBeam indicator on the mirror will turn OFF. To re-enable IntelliBeam, press the IntelliBeam button on the mirror. A different sensitivity setting is available for dealer diagnostics. This is done by pushing and holding this button for 20 seconds until the IntelliBeam indicator light flashes 3 times.

Front Fog Lamps

When the fog lamp switch is turned ON, ground from G304 is applied through the fog lamp switch signal circuit to the body control module (BCM) indicating the fog lamps ON request. In response to this signal, the BCM applies ground to the fog lamp relay control circuit energizing the FOG LAMP PCB Relay. With the relay energized, battery voltage is applied through the switch side of the relay, the FOG fuse, and the fog lamp supply voltage circuits illuminating the fog lamps. At the same time the BCM sends a GMLAN serial data message to the instrument panel cluster (IPC) requesting that the fog lamp indicator be illuminated. Ground for the left and right fog lamps is provided at G104.

Park, Tail, Marker & License Lamps (All countries except Japan, Taiwan, Korea)

The park, tail, license, and marker lamps are turned ON when the headlamp switch is placed in either the HEAD or PARK lamp positions, or anytime the automatic light control (ALC) turns the headlamps ON. When the headlamp switch is placed in the park lamp or headlamp positions, ground from G304 is applied through the signal circuit to the BCM indicating the park lamp request. In response to this signal, the BCM applies ground through the park lamp relay control circuit energizing the PRK LAMP Relay. With the relay energized, battery voltage is applied through the switch side of the relay, both park lamp fuses, and the supply voltage circuits illuminating the park, tail, marker, and license lamps.

Park, Position, Tail & License Lamps (Japan, Taiwan, Korea only)

The park, position, tail, and license lamps are turned ON when the headlamp switch is placed in either the HEAD or PARK lamp positions, or anytime the automatic light control (ALC) turns the headlamps ON. When the headlamp switch is placed in the park lamp or headlamp positions, ground from G304 is applied through the switch signal circuit to the BCM indicating the park lamp request. In response to this signal, the BCM applies ground through both park lamp relay control circuits energizing the PRK LAMP Relay and the RT PRK LAMP (EXP) relay. With the PRK LAMP Relay energized, battery voltage is applied through the switch side of the relay, the LT PRK LAMP fuse, and the supply voltage circuit to the left front position lamp, the left tail lamp, and to the switch side of the EXP LIC LAMP (EXP) Relay. With the RT PRK LAMP (EXP) relay energized, battery voltage is applied through the switch side of the relay, the RT PRK LAMP fuse, and the supply voltage circuits to the right front position lamp, the right tail lamp, and to the coil side of the EXP LIC LAMP (EXP) Relay energizing the relay. With the EXP LIC LAMP (EXP) Relay energized, battery voltage from the LT PRK LAMP fuse is applied through the switch side of the relay and the supply voltage circuits illuminating the license lamps.

Ground for the park lamps is supplied as follows

1. G104 provides ground for the left and right front position lamps
2. G402 provides ground for the left tail lamp
3. G403 provides ground for the right tail lamp and license lamps

Turn Signal Lamps

Battery voltage supplied to the body control module (BCM) from the fuses listed below is used for turn signal and hazard lamp operation.

1. LT TRN/SIG fuse for the left turn signals
2. CTSY/RF TRN fuse for the right front turn signal
3. RR TRN/SIG fuse for the right rear turn signal

When the turn signal switch is place in either the LEFT or RIGHT position, ground from G300 is applied through the turn signal switch signal circuit to the BCM indicating the turn signal request. In response to this signal, the BCM applies a pulsating voltage to the front and rear turn signal lamps supply voltage circuits cycling the lamps ON and OFF. At the same time the BCM sends a GMLAN serial data message to the instrument panel cluster (IPC) to cycle the appropriate turn signal indicator ON and OFF.

Ground for the turn signal lamps is supplied as follows

1. G104 provides ground for the left and right front turn signal lamps
2. G402 provides ground for the left rear stop/tail/turn signal lamps
3. G403 provides ground for the right rear stop/tail/turn signal lamps
4. The driver door module (DDM) provides a low reference for the left outside rearview mirror turn signal
5. The front passenger door module (FPDM) provides a low reference for the right outside rearview mirror turn signal

Hazard Lamps

The hazard flashers may be activated in any power mode. When the hazard switch is placed in the ON position, ground from G300 is applied through the hazard switch and the hazard switch signal circuit to the body control module (BCM) indicating the hazard lamps ON request. In response to this signal, the BCM applies a pulsating voltage to all front and rear turn signal lamps supply voltage circuits cycling the lamps ON and OFF. The BCM also sends a GMLAN serial data message to the instrument panel cluster (IPC) to cycle both turn signal indicators ON and OFF.

Cornering Lamps

The left and right cornering lamps are located within the headlamp assemblies. The BCM will illuminate the cornering lamp only during turn signal operation. When the left or right turn signal is turned ON, the BCM grounds the appropriate cornering lamp relay control circuit energizing the LF or RF CRN LAMP PCB RELAY. With the relay energized, battery voltage is applied through the switch side of the relay, the CRN LAMP fuse, and the cornering lamp supply voltage circuit illuminating the cornering lamp until the turn signal is turned OFF.

Stop Lamps (All countries except Japan, Taiwan, Korea)

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The body control module (BCM) provides a 5-volt reference voltage and low reference to the brake pedal position sensor. The position sensor provides an analog voltage signal back to the BCM that will increase as the brake pedal is applied. When the brake pedal is applied, the BCM will then apply battery voltage to the left and right stop/turn signal lamp supply voltage circuits and the center high mounted stop lamp (CHMSL) supply voltage circuit illuminating the stop lamps. At the same time the BCM applies battery voltage through the signal circuit to the transmission control module (TCM) and the engine control module (ECM) indicating that the brakes are applied.

Stop Lamps (Japan, Taiwan, Korea only)

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The body control module (BCM) provides a 5-volt reference voltage and low reference to the brake pedal position sensor. The position sensor provides an analog voltage signal back to the BCM that will increase as the brake pedal is applied. When the brake pedal is applied, the BCM will then apply battery voltage to the stop lamp relay control circuit illuminating the center high mounted stop lamp (CHMSL) and energizing the STOP LAMPS (EXP) Relay. With the relay energized, battery voltage from the STOP LAMP (EXP) fuse is applied through the switch side of the relay and the supply voltage circuit illuminating the stop lamps. At the same time the BCM applies battery voltage through the signal circuit to the transmission control module (TCM) and the engine control module (ECM) indicating that the brakes are applied.

Ground for the stop lamps is supplied as follows

1. G402 provides ground for the left rear stop/tail/turn signal lamps and for the CHMSL
2. G403 provides ground for the right rear stop/tail/turn signal lamps

The stop lamps on this vehicle will not illuminate unless the ignition is in the accessory, run, or crank positions. When the ignition is in the OFF position the stop lamps will not illuminate when the brake pedal is applied.

Battery voltage from the LT TRN/SIG and RT TRN/SIG fuses located in the rear fuse block is also used by the body control module (BCM) for stop lamp operation.

Backup Lamps

Battery voltage from the CHMSL/BCK-UP fuse located in the rear fuse block is supplied to the body control module (BCM) for backup lamp operation. When the gear selector is placed in to the REVERSE position, the powertrain control module (PCM) sends a GMLAN serial data message to the BCM indicating that the gear selector is in the reverse position. The BCM then applies battery voltage to the backup lamp supply voltage circuit illuminating the left and right backup lamps. Ground for the left backup lamp is provided at G402 and ground for the right backup lamp is provided at G403.

Battery Rundown Protection/Inadvertent Power

The BCM controls the lighting system through circuits that enable the exterior lamp functions of the park lamps, the head lamps, the fog lamps, and the interior lamps. The BCM opens these enabling circuits 10 minutes after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated during this time period, the timer resets for another 10 minutes.

The interior lighting consist of two groups; lamps that may not be manually dimmed (Interior Lamps) and lamps that may be dimmed (Interior Lamps Dimming).

The first group listed below includes lamps that may not be dimmed

1. Overhead Console Courtesy/Reading Lamps
2. Courtesy Lamp Module
3. Door Courtesy Lamps
4. Roof Rail Courtesy/Reading Lamps
5. Vanity Mirror Lamps
6. I/P Compartment Lamp
7. Rear Compartment Courtesy Lamp

Interior Lamps Features

The interior lamps system features the following functions

1. An illuminated entry feature that illuminates the courtesy lamps when entering the vehicle or activating the remote keyless entry system.
2. An illuminated exit feature that illuminates the courtesy lamps when the ignition key has been removed from the ignition.
3. An inadvertent power feature that supplies voltage to all interior lamps after the ignition is turned OFF. The inadvertent power feature will deactivate all interior lamps after 10 minutes to prevent battery rundown.
4. A theater dimming feature that will slowly dim the interior lamps from full brightness to OFF.
5. An lamp switch assembly that illuminates the courtesy lamps.
6. Individual switches for control of each interior lamp that is not illuminate with the interior lamp switch.

Courtesy Lamps

When either one of the front doors is opened, ground is applied through the door latch door open switch and the door open switch signal circuit to the door module indicating the door open position. In response to this signal, the door module sends a GMLAN serial data message to the BCM of the door open position. Or, when either one of the rear doors is opened, ground is applied through the rear door latch door open switch and the rear door open switch signal circuit to the BCM indicating the door open position. Once a door open message or signal is received, the BCM will then apply battery voltage from the CTSY/RF TRN fuse through the courtesy lamp supply voltage circuit illuminating the lamps listed below. At the same time the BCM sends a GMLAN serial data message to the driver door module (DDM) and the front passenger door module (FPDM) indicating the courtesy lamps ON request. In response to this message, the door modules apply battery voltage to the courtesy lamp supply voltage circuits illuminating the front door courtesy lamps. The front door modules also provide a ground through the low reference circuits to the courtesy lamps.

1. Courtesy lamp module (w/o V4U or BQ9)
2. Rear door courtesy lamps
3. Overhead console lamp (w/ V4U or BQ9)
4. Roof rail courtesy/reading lamps (w/ V4U or BQ9)
5. Dome lamp (w/ V4U or BQ9)
6. Middle door courtesy lamps (w/ V4U)

Courtesy Lamps Manual Operation

The courtesy lamps may be manually turned ON by the I/P dimmer switch. When the dimmer switch is placed in the DOME position, ground is applied through the dimmer switch and the courtesy lamp switch ON signal to the BCM indicating the courtesy lamps ON request. In response to this signal, the BCM then applies battery positive voltage from the CTSY/RF TRN fuse through the courtesy lamp supply voltage circuit illuminating the courtesy lamps listed above. The courtesy lamp ON operation of the dimmer switch will override any BCM operation of the interior lamps already in progress.

Keyless Entry Interior Illumination

When the driver uses the remote function actuator transmitter to unlock the doors, BCM receives a door-unlock signal. The BCM must have inputs that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF, and all the doors are closed. The BCM will then illuminate the courtesy lamps for approximately 25 seconds after the door is closed. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the RUN or START position the courtesy lamps will turn OFF immediately.

Courtesy/Illuminated Exit

The illuminated exit feature will activate the courtesy lamps when the key IN input of the BCM transitions from an active state to an inactive state (removing the ignition key). When the key is removed from the ignition, the key IN input to the BCM becomes inactive. The BCM will illuminate the courtesy lamps for approximately 25 seconds.

Theater Dimming

The theater dimming feature that will slowly dim the interior lamps from full brightness to OFF. The following actions will over ride the theater dimming feature causing the courtesy lamps to deactivate immediately if no other BCM function commands the courtesy lamps ON

1. A transition from active to inactive of the interior lamps switch, turning OFF the interior lamps switch
2. A LOCK command from the remote keyless entry system
3. A last door closed locking function, locking and closing all the doors

I/P Compartment Lamp

The BCM supplies battery positive voltage from the INT LAMPS fuse through the inadvertent power courtesy lamps circuit to the IP compartment lamp. When the IP compartment is opened, the IP compartment lamp switch closes to ground and the lamp illuminates.

Rear Compartment Lamp

The BCM supplies battery positive voltage from the INT LAMPS fuse through the inadvertent power courtesy lamps circuit to the rear compartment lamp. When the rear compartment is opened, the rear compartment lamp switch closes to ground and the lamp illuminates.

Courtesy Lamp Module or Roof Rail Courtesy/Reading Lamps

The courtesy/reading lamp is a duel purpose lamp that can be illuminated two different ways. First, the lamp can be turned ON during courtesy lamp operation as described above. Second, the lamps can be turned ON individually for reading lamp operation by the lamp switch. The BCM supplies battery voltage from the INT LAMPS fuse through the inadvertent power courtesy lamp circuit to the courtesy lamp module, overhead console lamp, or the roof rail courtesy/reading lamps for reading lamp operation only. Ground for these lamps is provided at G402.

Sunshade Vanity Mirror Lamps

The BCM supplies battery voltage from the INT LAMPS fuse through the inadvertent power courtesy lamps circuit to the front and rear vanity mirror lamps. When the vanity mirror cover on the sunshade is opened, the vanity mirror lamp switch is closed to ground and the lamp illuminates. Ground for the vanity mirror lamps is provided at G402.

Interior Lamps Dimming

The second interior lighting group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination, LED illumination and incandescent lamps.

1. Headlamp switch
2. Hazard switch
3. Ashtray lamp
4. HVAC control module
5. Driver information center (DIC)
6. Clock
7. Radio
8. Rear door window switches
9. Traction control switch
10. Floor shifter assembly
11. Garage door opener transmitter
12. Sunroof switch
13. Sunshade switch
14. Rear seat heated seat switches
15. Rear seat lumbar switches
16. Middle door window switches (w/ V4U)
17. Auxiliary HVAC control module (w/ CJ4)
18. Steering wheel controls

When the ignition switch is turned to the RUN position, the instrument panel cluster (IPC), radio VF display, and the HVAC control assembly turns ON at maximum brightness. When the headlamp switch is in the PARK or HEADLAMP ON position, all incandescent and LED back lighting turn ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. The dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The BCM supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the I/P lamps supply voltage circuit and the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness. At the same time the BCM also sends a GMLAN serial data message to the driver door module (DDM) and the front passenger door module (FPDM) indicating the back lighting request with the desired level of brightness. The door modules then illuminate the door switches and the heated/cooled seat switch back lighting to the requested intensity.

Battery Rundown Protection / Inadvertent Power

The BCM controls the lighting system through circuits that enable the exterior lamp functions of the park lamps, the head lamps, the fog lamps, and the interior lamps. The BCM opens these enabling circuits 10 minutes after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated during this time period, the timer resets for another 10 minutes.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Relay Replacement (Attached to Wire Harness)
• Inside Rearview Mirror Replacement
• Driver Information Display Switch Replacement
• Auxiliary Heater and Air Conditioning Control Replacement
• Radio Replacement
• Steering Wheel Control Switch Assembly Replacement
• Roof Console Replacement
• Information Center Telltale Assembly Replacement
• Rear Seat Heater Switch Replacement
• Electronic Traction Control Switch Replacement
• Sunroof Switch Replacement
• Garage Door Opener Replacement
• Rear Side Door Window Switch Replacement
• Rear Seat Lumbar Control Switch Replacement
• Checking Aftermarket Accessories
• Turn Signal Multifunction Switch Replacement
• Door Lock and Side Window Switch Replacement - Driver Side
• Accelerator Pedal Position Sensor Replacement
• Fastener Notice
• Instrument Panel Outer Air Outlet Replacement - Left Side
• Front Side Door Trim Panel Replacement
• Headlining Trim Panel Replacement
• Front Bumper Fascia Replacement
• Halogen Bulb Caution
• Front Wheelhouse Liner Replacement
• DTC B1395
• Interior Lamp Switch Replacement
• Fastener Tightening Specifications