Lighting Systems - DTC b1461 to p0573 Cadillac XLR I

Diagnostic Fault Information

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

Battery positive voltage is applied to the headlamp control module at all times and when the ignition switch is in the RUN and CRANK positions. The headlamp control module has an operational voltage range of about 10.5-16 volts and is only fully functional when the ignition switch is in the RUN position. The voltage input from the ignition switch wakes the headlamp control module microprocessor. The headlamp control module receives serial data messages via GMLAN from the engine control module (ECM), transmission control module (TCM), electronic brake control module (EBCM), and body control module (BCM) with regards to power mode, speed, steering angle, transmission gear selection, and headlamp switch status. The headlamp control module calculates the headlamp angle and sends commands to the left and right headlamp actuators. The headlamp actuators drive the headlamps to the position commanded by the headlamp control module. The headlamp control module monitors the headlamp actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in memory and the driver will be notified with a message displayed over the driver information center (DIC) located on the instrument panel cluster (IPC). For more detailed information concerning exterior lighting operation, refer to Exterior Lighting Systems Description and Operation .

Conditions for Running the DTC

The headlamp control module performs this diagnostic test mode every 250 milliseconds when the following conditions are met

1. Battery voltage must be between 10-16 volts.
2. Ignition is in the RUN position.
3. Headlamp switch is in the AUTO position.
4. High or low beam headlamps must be active.
5. Vehicle speed greater than 2 mph.
6. Transmission is in the DRIVE position.

DTC B1461 00

This DTC will set when the headlamp control module detects an open or short to voltage in the right headlamp actuator control circuits.

DTC B1461 02

This DTC will set when the headlamp control module detects a short to ground in the right headlamp actuator control circuits.

DTC B1461 39

This DTC will set when the headlamp control module detects an internal circuit failure.

DTC B1461 54

This DTC will set when the headlamp control module detects a high temperature condition in the right headlamp actuator control circuits.

Action Taken When the DTC Sets

When DTC B1461 sets, the headlamp control module will disable all requests to both headlamp actuators and headlamp position will be maintained.

Conditions for Clearing the DTC

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 40 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Scan Tool Reference

1. «Scan Tool Data List»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-1-of-2)

Circuit/System Testing

DTC B1461 00

1. Ignition OFF, disconnect the headlamp control module harness connector.
2. Ignition ON, verify that a test lamp does not illuminate between ground and each LH AFS motor control circuit one at a time. If the test lamp illuminates, repair the effected LH AFS motor control circuit for a short to voltage.
3. Ignition OFF, test each LH AFS motor control circuit for good continuity. If good continuity is not detected, repair the affected LH AFS motor control circuit for shorts to each other, or an open/high resistance. If the circuits test normal, test or replace the LH AFS motor.
4. If all circuits test normal, replace the headlamp control module.

DTC B1461 02

1. Ignition OFF, disconnect the headlamp control module harness connector.
2. Verify that a test lamp does not illuminate between battery positive voltage and each LH AFS motor control circuit one at a time. If the test lamp illuminates, repair the effected LH AFS motor control circuit for a short to ground. If the circuits test normal, test or replace the LH AFS motor.
3. If all circuits test normal, replace the headlamp control module.

DTC B1461 39

1. Ignition ON, install a scan tool and clear all DTCs.
2. Operate the vehicle within the conditions for running the DTC.
3. With the scan tool, retrieve DTCs and determine if DTC B1461 39 has reset as current. If DTC B1461 39 resets as a current DTC, replace the headlamp control module.

DTC B1461 54

1. Ignition ON, install a scan tool and clear all DTCs.
2. Operate the vehicle within the conditions for running the DTC.
3. With the scan tool, retrieve DTCs and determine if DTC B1461 54 has reset as current. If DTC B1461 54 resets as a current DTC, replace the headlamp control module.

Repair Procedures

Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(/cadillac/xlr/i-2003-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for headlamp control module replacement, setup, and programming
2. «Headlamp Assembly or Headlamp Bulb and/or Cornering, Sidemarker, Park, Turn Signal Bulb Replacement»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-2-of-2)

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Battery positive voltage is applied to the headlamp control module at all times and when the ignition switch is in the RUN and CRANK positions. The headlamp control module has an operational voltage range of about 10.5-16 volts and is only fully functional when the ignition switch is in the RUN position. The voltage input from the ignition switch wakes the headlamp control module microprocessor. The headlamp control module receives serial data messages via GMLAN from the engine control module (ECM), transmission control module (TCM), electronic brake control module (EBCM), and body control module (BCM) with regards to power mode, speed, steering angle, transmission gear selection, and headlamp switch status. The headlamp control module calculates the headlamp angle and sends commands to the left and right headlamp actuators. The headlamp actuators drive the headlamps to the position commanded by the headlamp control module. The headlamp control module monitors the headlamp actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in memory and the driver will be notified with a message displayed over the driver information center (DIC) located on the instrument panel cluster (IPC). For more detailed information concerning exterior lighting operation, refer to Exterior Lighting Systems Description and Operation .

The headlamp control module performs this diagnostic test mode every 250 milliseconds when the following conditions are met

1. Battery voltage must be between 10-16 volts.
2. Ignition is in the RUN position.
3. Headlamp switch is in the AUTO position.
4. High or low beam headlamps must be active.
5. Vehicle speed greater than 2 mph.
6. Transmission is in the DRIVE position.

DTC B1462 00

This DTC will set when the headlamp control module detects an open or short to voltage in the right headlamp actuator control circuits.

DTC B1462 02

This DTC will set when the headlamp control module detects a short to ground in the right headlamp actuator control circuits.

DTC B1462 39

This DTC will set when the headlamp control module detects an internal circuit failure.

DTC B1462 54

This DTC will set when the headlamp control module detects a high temperature condition in the right headlamp actuator control circuits.

When DTC B1462 sets, the headlamp control module will disable all requests to both headlamp actuators and headlamp position will be maintained.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 40 consecutive malfunction-free ignition cycles have occurred.

Headlights/Daytime Running Lights (DRL) Schematics

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Scan Tool Reference

1. «Scan Tool Data List»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-1-of-2)

DTC B1462 00

1. Ignition OFF, disconnect the headlamp control module harness connector.
2. Ignition ON, verify that a test lamp does not illuminate between ground and each RH AFS motor control circuit one at a time. If the test lamp illuminates, repair the effected RH AFS motor control circuit for a short to voltage.
3. Ignition OFF, test each RH AFS motor control circuit for good continuity. If good continuity is not detected, repair the affected RH AFS motor control circuit for shorts to each other, or an open/high resistance. If the circuits test normal, test or replace the RH AFS motor.
4. If all circuits test normal, replace the headlamp control module.

DTC B1462 02

1. Ignition OFF, disconnect the headlamp control module harness connector.
2. Verify that a test lamp does not illuminate between battery positive voltage and each RH AFS motor control circuit one at a time. If the test lamp illuminates, repair the effected RH AFS motor control circuit for a short to ground. If the circuits test normal, test or replace the RH AFS motor.
3. If all circuits test normal, replace the headlamp control module.

DTC B1462 39

1. Ignition ON, install a scan tool and clear all DTCs.
2. Operate the vehicle within the conditions for running the DTC.
3. With the scan tool, retrieve DTCs and determine if DTC B1461 39 has reset as current. If DTC B1461 39 resets as a current DTC, replace the headlamp control module.

DTC B1462 54

1. Ignition ON, install a scan tool and clear all DTCs.
2. Operate the vehicle within the conditions for running the DTC.
3. With the scan tool, retrieve DTCs and determine if DTC B1461 54 has reset as current. If DTC B1461 54 resets as a current DTC, replace the headlamp control module.

Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(/cadillac/xlr/i-2003-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for headlamp control module replacement, setup, and programming
2. «Headlamp Assembly or Headlamp Bulb and/or Cornering, Sidemarker, Park, Turn Signal Bulb Replacement»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-2-of-2)

Circuit Description

The body control module (BCM) supplies battery voltage to the courtesy lamps, underhood lamp, instrument panel (I/P) compartment lamp, console lamp, and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the courtesy lamp supply voltage circuit to prevent a total battery discharge condition.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1480 Battery Rundown Protection Circuit

DTC B1480

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

DTC B1480 will set when the courtesy lamp supply voltage circuit that feeds the courtesy lamps, underhood lamp, IP compartment lamp, console lamp and both visor vanity mirror lamps is shorted to ground for longer than 1 second.

The courtesy lamps, underhood lamp, I/P compartment lamp, console lamp, and both visor vanity mirror lamps will not operate.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

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 .

DTC B1480

The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying battery voltage to the front fog lamp relay control circuit. When the front fog lamp relay is energized, battery voltage is applied via the FOG LAMP fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps.

This diagnostic procedure supports the following DTC

DTC B2530 Front Fog Lamps Control Circuit

DTC B2530

Battery voltage must be between 9-16 volts.

1. DTC B2530 02 will set when the BCM detects a short to ground in the front fog lamp relay control circuit.
2. DTC B2530 05 will set when the BCM detects an open or short to voltage in the front fog lamp relay control circuit.

1. When DTC B2530 02 is present, the front fog lamps will not operate when the park lamps are ON and the front fog lamp switch is active.
2. When DTC B2530 05 is present, the front fog lamps and/or the front fog lamp indicator will be ON at all times or will not operate.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

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 .

DTC B2530

The rear fog lamp switch signal circuit is grounded momentarily by pressing the rear fog lamp switch. The body control module (BCM) energizes the rear fog lamp relay by applying battery voltage to the rear fog lamp relay control circuit. When the rear fog lamp relay is energized, battery voltage is applied via the REAR FOG/ALDL TOP SW fuse to the rear fog lamp supply voltage circuit which illuminates the rear fog lamps.

This diagnostic procedure supports the following DTC

DTC B2540 Rear Fog Lamps Control Circuit

DTC B2540

Battery voltage must be between 9-16 volts.

1. DTC B2540 02 will set when the BCM detects a short to ground in the rear fog lamp relay control circuit.
2. DTC B2540 05 will set when the BCM detects an open or short to voltage in the rear fog lamp relay control circuit.

1. When DTC B2540 02 is present, the rear fog lamps will not operate when the park lamps are ON and the rear fog lamp switch is active.
2. When DTC B2540 05 is present, the rear fog lamps and/or the rear fog lamp indicator will be ON at all times or will not operate.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

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 .

DTC B2540

When the turn signal/multifunction switch is placed in the headlamps high or flash to pass (FTP) position, ground is applied to the body control module (BCM) through the headlamp high beam signal circuit or the flash to pass switch signal circuit. The BCM then applies ground to the headlamp high beam relay control circuit which energizes the high beam relay, applying battery voltage to the high beam headlamps.

This diagnostic procedure supports the following DTC

DTC B2580 Headlamp High Beam Control Circuit

DTC B2580

Battery voltage must be between 9-16 volts.

1. DTC B2580 01 will set when the BCM detects a short to battery voltage in the headlamp high beam relay control circuit.
2. DTC B2580 06 will set when the BCM detects an open or short to ground in the headlamp high beam relay control circuit.

1. When DTC B2580 01 is present, the high beam headlamps will not operate.
2. When DTC B2580 06 is present, the high beam headlamps will remain ON.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

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 .

DTC B2580

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

DTC B2585

Battery positive voltage is applied at all times from the PARK LAMPS fuse to both the coil and switched sides of the PARK LAMP Relay in the underhood electrical center. Ground is applied from G201 to the multifunction switch at all times. When the headlamp switch is place in either the HEAD or PARK position, ground is applied to the park lamp relay control circuit. This energizes the PARK LAMP Relay and applies battery positive voltage to all of the park, tail, license, and marker lamps. For more detailed information concerning park lamp operation refer to Exterior Lighting Systems Description and Operation .

Battery voltage must be between 9-16 volts.

1. DTC B2585 01 will set when the BCM detects a short to battery voltage in the park lamp relay control circuit.
2. DTC B2585 06 will set when the BCM detects an open or short to ground in the park lamp relay control circuit.

Actions Taken When the DTC Sets

1. When DTC B2585 01 is present, the park lamps will not operate.
2. When DTC B2585 06 is present, the park lamps will remain ON.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Exterior Lights Schematics

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__circuit-testing)
2. «Connector Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__wiring-repairs)

Scan Tool Reference

1. «Scan Tool Data List»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-1-of-2__scan-tool-data-list)
2. «Scan Tool Data Definitions»(/cadillac/xlr/i-2003-2009/remont/exterior-lights/#lighting-systems-introduction-1-of-2)

1. Ignition OFF, disconnect the park lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal C8 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal A9 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 control circuit terminal C9 for a short to ground. If the circuit tests normal, test or replace the park lamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal A8 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 A9 and the control circuit terminal C8.
6. Command the parks lamps ON and OFF with the park lamp switch. 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. If all circuits test normal, test or replace the park lamp relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) or «Relay Replacement (Attached to Wire Harness)»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) .
2. «Control Module References»(/cadillac/xlr/i-2003-2009/remont/communication-devices/#computerintegrating-systems__control-module-references) for BCM replacement, setup, and programming.

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2 and 4.9 volts depending on outside lighting conditions. The HVAC control module provides a low reference ground and a 5-volt reference signals to the ambient light sensor. The HVAC control module monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. The HVAC control module sends a signal to the body control module (BCM) via class 2 serial data commanding the BCM to turn the front turn signal lamps on steady (non-flashing). Any function or condition that turns on the headlamps will cancel the DRL operation. With the turn signal/multifunction switch in the OFF position, the turn signal lamps will either be turned ON or OFF after a 30-second delay, depending on whether daylight or low light conditions are sensed by the ambient light sensor.

This diagnostic procedure supports the following DTC

DTC B2646 Ambient Light Sensor Circuit Performance

Battery voltage must be between 9-16 volts.

The HVAC control module detects the ambient light sensor signal circuit is less than 5 counts (0.2 volts) or greater than 250 counts (4.75 volts) for 3 consecutive tests.

The HVAC control module defaults to low light status.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

DTC B2646

When the turn signal/multifunction switch is placed in the left turn position, ground is applied to the body control module (BCM) through the left turn signal switch circuit. The BCM then applies a pulsating voltage to the LF and LR turn signal lamps through the LF and LR turn signal voltage supply circuits.

This diagnostic procedure supports the following DTC

DTC B3948 Left Front Turn Signal Circuit

DTC B3948

Battery voltage must be between 9-16 volts.

1. DTC B3948 02 will set when the BCM detects a short to ground in the LF turn signal voltage supply circuit.
2. DTC B3948 05 will set when the BCM detects an open or short to voltage in the LF turn signal voltage supply circuit.

1. When DTC B3948 02 is present, the LF turn signal lamp will not operate.
2. When DTC B3948 05 is present, the LF turn signal lamp will be ON at all times for a short to voltage condition. For an open condition, the LF turn signal lamp will be inoperative.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Check the LF turn signal bulb. If the bulb is open, DTC B3948 05 will set as current only.

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 .

DTC B3948

When the turn signal/multifunction switch is placed in the right turn position, ground is applied to the body control module (BCM) through the right turn signal switch circuit. The BCM then applies a pulsating voltage to the RF and RR turn signal lamps through the RF and RR turn signal voltage supply circuits.

This diagnostic procedure supports the following DTC

DTC B3949 Right Front Turn Signal Circuit

DTC B3949

Battery voltage must be between 9-16 volts.

1. DTC B3949 02 will set when the BCM detects a short to ground in the RF turn signal voltage supply circuit.
2. DTC B3949 05 will set when the BCM detects an open or short to voltage in the RF turn signal voltage supply circuit.

1. When DTC B3949 02 is present, the RF turn signal lamp will not operate.
2. When DTC B3949 05 is present, the RF turn signal lamp will be ON at all times for a short to voltage condition. For an open condition, the RF turn signal lamp will be inoperative.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Check the RF turn signal bulb. If the bulb is open, DTC B3949 05 will set as current only.

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 .

DTC B3949

When the turn signal/multifunction switch is placed in the left turn position, ground is applied to the body control module (BCM) through the left turn signal switch circuit. The BCM then applies a pulsating voltage to the LF and LR turn signal lamps through the LF and LR turn signal voltage supply circuits.

This diagnostic procedure supports the following DTC

DTC B3950 Left Rear Turn Signal Circuit

DTC B3950

Battery voltage must be between 9-16 volts.

1. DTC B3950 02 will set when the BCM detects a short to ground in the LR turn signal voltage supply circuit.
2. DTC B3950 05 will set when the BCM detects an open or short to voltage in the LR turn signal voltage supply circuit.

1. When DTC B3950 02 is present, the LR turn signal lamp will not operate.
2. When DTC B3950 05 is present, the LR turn signal lamp will be on at all times for a short to voltage condition. For an open condition, the LR turn signal lamp will be inoperative.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Check the LR turn signal bulb. If the bulb is open, DTC B3950 05 will set as current only.

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 .

DTC B3950

When the turn signal/multifunction switch is placed in the right turn position, ground is applied to the body control module (BCM) through the right turn signal switch circuit. The BCM then applies a pulsating voltage to the RF and RR turn signal lamps through the RF and RR turn signal voltage supply circuits.

This diagnostic procedure supports the following DTC

DTC B3951 Right Rear Turn Signal Circuit

DTC B3951

Battery voltage must be between 9-16 volts.

1. DTC B3951 02 will set when the BCM detects a short to ground in the RR turn signal voltage supply circuit.
2. DTC B3951 05 will set when the BCM detects an open or short to voltage in the RR turn signal voltage supply circuit.

1. When DTC B3951 02 is present, the RR turn signal lamp will not operate.
2. When DTC B3951 05 is present, the RR turn signal lamp will be on at all times for a short to voltage condition. For an open condition, the RR turn signal lamp will be inoperative.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 100 consecutive malfunction free ignition cycles have occurred.

Check the RR turn signal bulb. If the bulb is open, DTC B3951 05 will set as current only.

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 .

DTC B3951

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, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).

This diagnostic procedure supports the following DTC

DTC C0277 Brake Pedal Position Sensor Circuit

DTC C0277

Ignition voltage is within the normal operating voltage range.

DTC C0277 06

The BCM detects an open or short to ground in the brake pedal position sensor signal circuit for 0.5 seconds or greater.

DTC C0277 07

The BCM detects a short to battery voltage in the brake pedal position sensor signal or low reference circuits for 0.5 seconds or greater.

DTC C0277 09

The BCM detects the brake pedal position sensor signal is changing faster than possible under normal operating conditions.

1. The Service Vehicle Soon indicator is commanded ON.
2. When DTC C0277 is set as current, the vehicle will not start.
3. 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.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 50 malfunction-free ignition cycles have occurred.
4. A DTC will not clear the current status until the next ignition cycle.

1. If DTC C0277 09 is set, replace the brake pedal position sensor. If the DTC resets, replace the BCM.
2. 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»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor) .

DTC C0277

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, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).

This diagnostic procedure supports the following DTC

DTC C0278 Brake Pedal Position Sensor Not Calibrated

DTC C0278

Ignition voltage is within the normal operating voltage range.

DTC C0278 00 will set when the brake pedal position sensor home position is not learned.

1. The Service Vehicle Soon indicator is commanded ON.
2. When DTC C0278 is set as current, the vehicle will not start.
3. Stop lamps may not activate at the expected brake pedal positions.

1. A successful brake pedal position sensor calibration has been performed.
2. The condition responsible for setting the DTC no longer exists.
3. You issue a scan tool CLEAR DTCs command.
4. A history DTC will clear once 50 malfunction-free ignition cycles have occurred.

1. If DTC C0278 00 is set, recalibrate the brake pedal position sensor.
2. 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»(/cadillac/xlr/i-2003-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__testing-for-intermittent-conditions-and-poor) .

DTC C0278

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, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).

This diagnostic procedure supports the following DTC

DTC C0870 Device Voltage Reference Output 1 Circuit

DTC C0870

Ignition voltage is within the normal operating voltage range.

DTC C0870 03

The BCM detects a short to ground in the brake pedal position sensor voltage reference circuit for 0.5 seconds or greater.

DTC C0870 07

The BCM detects a short to battery voltage in the brake pedal position sensor voltage reference circuits for 0.5 seconds or greater.

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.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 50 malfunction-free ignition cycles have occurred.
4. A DTC will not clear the current status until the next ignition cycle.

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 .

DTC C0870

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 brake pedal position sensor receives a low reference signal and a 5-volt reference voltage from the body control module (BCM) when the driver applies the brakes. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop/turn signal voltage supply circuit to illuminate the stop lamps and the center high mounted stop lamp (CHMSL). The BCM also sends a brake pedal position sensor signal to the engine control module (ECM) as well as a serial data message to indicate the application of the brake pedal.

This diagnostic procedure supports the following DTC

DTC P0572 Brake Switch Circuit 1 Low Voltage

1. The ignition is in the ON position.
2. Battery voltage greater than 11.5 volts.

The ECM detects a short to ground on the signal circuit when the serial data message from the BCM indicates the brakes are applied.

1. The ECM stores the DTC to memory.
2. The ECM will record the operating conditions at the time the diagnostic failed. The ECM stores this information in Failure Records.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 40 malfunction free ignition cycles have occurred.

DTC P0572

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 brake pedal position sensor receives a low reference signal and a 5-volt reference voltage from the body control module (BCM) when the driver applies the brakes. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop/turn signal voltage supply circuit to illuminate the stop lamps and the center high mounted stop lamp (CHMSL). The BCM also sends a brake pedal position sensor signal to the engine control module (ECM) as well as a serial data message to indicate the application of the brake pedal.

This diagnostic procedure supports the following DTC

DTC P0573 Brake Switch Circuit 1 High Voltage

1. The ignition is in the ON position.
2. Battery voltage greater than 11.5 volts.

The ECM detects an open or short to voltage on the signal circuit when the serial data message from the BCM indicates the brake are applied.

1. The ECM stores the DTC to memory.
2. The ECM will record the operating conditions at the time the diagnostic failed. The ECM stores this information in Failure Records.

1. The condition responsible for setting the DTC no longer exists.
2. You issue a scan tool CLEAR DTCs command.
3. A history DTC will clear once 40 malfunction-free ignition cycles have occurred.

DTC P0573

See also:
• Diagnostic System Check - Vehicle
• Exterior Lighting Systems Description and Operation
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Scan Tool Data List
• Scan Tool Data Definitions
• Diagnostic Repair Verification
• Control Module References
• Master Electrical Component List
• Relay Replacement (Within an Electrical Center)
• Sun Load Sensor Replacement