Antilock Brake System with Traction Control System & Stability Control System Buick LaCrosse I

Fastener Tightening Specifications

Fastener Tightening Specifications

ABS Schematic Icons

ABS Schematic Icons Icon Icon Definition IMPORTANT: Twisted-pair wires provide an effective shield that helps protect sensitive electronic components from electrical interference. If the wires were covered with shielding, install new shielding. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 9 turns per 31 cm (12 in) as measured anywhere along the length of the wires. The outside diameter of the twisted wires must not exceed 6.0 mm (0.25 in)

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ABS Connector End Views

Brake Fluid Pressure Sensor (JL4/JL9) Connector Part Information OEM: 15324236 (Delphi) 2-967642-1 (Tyco) Service: 15306334 3-Way F Quadlok Micro Series (GY) Pin Wire Color Circuit No. Function 1 GY/BK 1798 Ground 2 OG 1575 Brake Pressure Sensor Signal 3 GY 596 5-Volt Reference

Electronic Brake Control Module (EBCM) Connector Part Information OEM: 15326390 Service: 12167314 30-Way F GT 150, 280 Mixed Series Sealed (BK) Pin Wire Color Circuit No. Function 1 BN/WH 2086 Yaw Rate Sensor Test Control (JL4/JL9) 2 BN 882 Right Rear Wheel Speed Sensor Signal 3 WH 883 Right Rear Wheel Speed Sensor Low Reference 4 D-GN 872 Right Front Wheel Speed Sensor Signal 5 TN 833 Right Front Wheel Speed Sensor Low Reference 6 WH 17 Stop Lamp Switch Signal 7 WH 121 Engine Speed Signal (LY7) 8 PK 1039 Ignition 1 Voltage 9 TN/BK 464 Delivered Torque Signal (NW7) 10 L-BU 715 Lateral Accelerometer Signal (JL4/JL9) 11 WH 121 Engine Speed Signal (L26 w/JL9) TN 2501 High Speed GMLAN Serial Data Bus (-) (LY7 w/JL9) 12 BK/WH 251 Ground 13 RD 1442 Battery Positive Voltage 14 OG 1740 Battery Positive Voltage 15 BK/WH 251 Ground 16 GY 930 5-Volt Reference (JL4/JL9) 17 OG 1575 Brake Pressure Sensor Signal (JL4/JL9) 18 GY/BK 1798 Ground (JL4/JL9) 19 TN/WH 2500 High Speed GMLAN Serial Data Bus (+) (JL4/JL9) 20 L-BU 830 Left Front Wheel Speed Sensor Signal 21 YE 873 Left Front Wheel Speed Sensor Low Reference 22 BK 884 Left Rear Wheel Speed Sensor Signal 23 RD 885 Left Rear Wheel Speed Sensor Low Reference 24 - - Not Used 25 L-BU 1122 ABS/TCS Class 2 Serial Data 26 D-BU 716 Yaw Rate Sensor Signal (JL4/JL9) 27 OG/BK 463 Requested Torque Signal (NW7) 28 GY 596 5-Volt Reference (JL4/JL9) 29 BN 1295 Variable Effort Steering Actuator Control (NV8) 30 WH 1294 Variable Effort Steering Actuator Supply Voltage (NV8)

Steering Angle Sensor (JL4/JL9) Connector Part Information OEM: 15324351 (Delphi) 1 928 404 025 (Bosch) Service: 15324351 7-Way F (BK) Pin Wire Color Circuit No. Function 1 GY/BK 1798 Ground 2 PK 1039 Ignition 1 Voltage 3 TN/WH 2500 High Speed GMLAN Serial Data Bus (+) 4 TN 2501 High Speed GMLAN Serial Data Bus (-) 5-7 - - Not Used

Wheel Speed Sensor (WSS) - LF Connector Part Information OEM: 12052644 Service: See Catalog 2-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A YE 873 Left Front Wheel Speed Sensor Low Reference B L-BU 830 Left Front Wheel Speed Sensor Signal

Wheel Speed Sensor (WSS) - LR Connector Part Information OEM: 12052644 2-Way F Metri-Pack 150 Series Sealed (GY) Service: See Catalog 2-Way F Metri-Pack 150 Series, Sealed (GY) Pin Wire Color Circuit No. Function A BK 884 Left Rear Wheel Speed Sensor Signal B RD 885 Left Rear Wheel Speed Sensor Low Reference

Wheel Speed Sensor (WSS) - RF Connector Part Information OEM: 12052644 Service: See Catalog 2-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A TN 833 Right Front Wheel Speed Sensor Low Reference B D-GN 872 Right Front Wheel Speed Sensor Signal

Wheel Speed Sensor (WSS) - RR Connector Part Information OEM: 12052644 2-Way F Metri-Pack 150 Series Sealed (GY) Service: See Catalog 2-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A BN 882 Right Rear Wheel Speed Sensor Signal B WH 883 Right Rear Wheel Speed Sensor Low Reference

Yaw and Lateral Acceleration Sensor (JL4/JL9) Connector Part Information OEM: 15355474 (Delphi) 1-967616-1 (AMP) Service: 15306420 6-Way F MQ5 Sealed (BK) Pin Wire Color Circuit No. Function 1 GY 930 5-Volt Reference 2 BN/WH 2086 Yaw Rate Sensor Test Control 3 PK 1039 Ignition 1 Voltage 4 D-BU 716 Yaw Rate Sensor Signal 5 L-BU 715 Lateral Accelerometer Signal 6 GY/BK 1798 Ground

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Antilock Brake System

Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check 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 will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Scan Tool Output Controls

Scan Tool Data List

The EBCM Scan Tool Data Lists contain all the antilock brake system related parameters that are available on the scan tool. The parameters on the list are arranged in alphabetical order. The "Column" data list shows the location of the parameter on the scan tool displayed menu selections.

Use the EBCM Scan Tool Data Lists as directed by a diagnostic table or in order to supplement the diagnostic procedures. Begin all the diagnostic procedures with the ABS Diagnostic Starting Point. Use the EBCM Scan Tool Data Lists only after the following is determined

1. There is no published DTC procedure nor published symptom procedure for the customer concern. OR
2. The DTC or symptom diagnostic procedure indicated by the diagnostic system check does not resolve the customer concern.

The Typical Data Values are obtained from a properly operating vehicle under the conditions specified in the first row of the Scan Tool Data List table. Comparison of the parameter values from the suspect vehicle with the Typical Data Values may reveal the source of the customer concern.

EBCM Scan Tool Data List

Data Display/Definitions

The Scan Tool Data Display/Definitions contains a brief description of all the ABS/TCS/VSES data parameters. The menus available depend on the number and type of system on the vehicle and are listed below in alphanumeric order.

1. ABS DATA
2. TCS DATA
3. VSES DATA

Diagnostic Test Drive

When servicing vehicles the vehicle stability enhancement system (VSES), test drives will be necessary to allow all tests to be run and all system functions to be enabled and exercised. A test drive may also be required to duplicate specific DTCs covered in this section. The diagnostic system check including test drive, should be run when vehicle repairs are complete in order to verify the repair.

The diagnostic test drive will vary for ABS/TCS or VSES problems.

The following is a suggested VSES diagnostic test drive.

1. Read the Diagnostic Aids and the Conditions for Setting the DTC.
2. Reconnect any previously disconnected components.
3. Start the engine.
4. Drive the vehicle under the following conditions for at least 10 minutes. At no times should any unlawful or unsafe maneuvers be performed. Highway driving Rough roads Perform turning maneuvers, curved freeway entrance ramp, parking lot maneuvers and high steering angles and yaw rates at low speeds. Verify customers concern and duplicate driving conditions. With the engine still running use the scan tool and check for any DTCs. If any DTCs are set, perform the appropriate DTC table.

History Data

Enhanced diagnostic information is found in the History Data function of the scan tool. Enhanced diagnostic information provides the service technician with specific malfunction occurrence information.

The scan tool will display the last 3 DTCs to occur, one at a time. The DTC with the most recent occurrence will be displayed first. Each DTC will include the following

1. The number of drive cycles since the DTC last occurred.
2. The number of occurrences for the DTC since the scan tool DTC information was last cleared.

The most recent DTC will also display various data parameters with values from the time of the DTC occurrence.

Diagnostic Strategy

In difficult diagnostic situations use the above information to identify malfunction occurrence trends. Ask question such as the following

1. Did the malfunction only occur once over a large number of drive cycles, indicating an unusual condition present when it occurred?
2. Does the malfunction occur infrequently over a large number of drive cycles, indicating that special diagnostic techniques may be required to identify the source of the malfunction?

A malfunction that occurs more frequently increases the odds of finding the cause of the malfunction.

Use the information in order to determine if a DTC is intermittent. Use the information in order to determine if the DTC has not set for long periods of time due to weather changes or a repair prior to this visit.

Circuit Description

As the wheel spins, the wheel speed sensor produces an AC signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC C0035 Left Front Wheel Speed Sensor Circuit
2. DTC C0036 Left Front Wheel Speed Sensor Circuit Range Performance
3. DTC C0040 Right Front Wheel Speed Sensor Circuit
4. DTC C0041 Right Front Wheel Speed Sensor Circuit Range Performance
5. DTC C0045 Left Rear Wheel Speed Sensor Circuit
6. DTC C0046 Left Rear Wheel Speed Sensor Circuit Range Performance
7. DTC C0050 Right Rear Wheel Speed Sensor Circuit
8. DTC C0051 Right Rear Wheel Speed Sensor Circuit Range Performance

C0035 C0040 C0045 C0050

The ignition is ON.

C0036 C0041 C0046 C0051

1. Vehicle speed is over 40 km/h (25 mph).
2. The brake pedal is not pressed.
3. The ABS is not active.

One of the following conditions exists for 0.02 second

1. A short to voltage in the wheel speed sensor signal circuit
2. An open in the wheel speed sensor signal circuit

All of the following conditions exists for 0.01 second

1. The suspect wheel speed equals zero.
2. The other wheel speeds are greater than 40 km/h (25 mph) for 0.01 second.
3. The suspect wheel equals zero during drive off and the other wheels are greater than 18 km/h (11 mph).
4. A short to ground the wheel speed sensor signal circuit is shorted to ground.
5. A deviation of 2 wheel speeds at either side of the vehicle greater than 6 km/h (4 mph) or at the front axle greater than 10 km/h (6 mph) for a time period of 10-20 seconds.

Action Taken When the DTC Sets

If equipped, the following actions occur

1. The EBCM disables the ABS/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A DTC malfunction will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The Red BRAKE Warning indicator could turn ON.

Conditions for Clearing the DTC

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

If the customer comments that the ABS indicator is ON only during moist environmental conditions (rain, snow, vehicle wash, etc.), inspect the wheel speed sensor wiring for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure

1. Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater solution, add 2 teaspoons of salt to 354 ml (12 oz) of water.
2. Test drive the vehicle over various road surfaces (bumps, turns, etc.) above 40 km/h (25 mph) for at least 30 seconds.
3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
4. Rinse the are thoroughly when completed.

Under the following conditions, 2 Wheel Speed Sensor Input is 0 DTCs are set

1. The 2 suspect wheel speeds equal zero for 10-20 seconds.
2. The other wheel speeds are greater than 16 km/h (10 mph).
3. The other wheel speeds are within 11 km/h (7 mph) of each other.

Diagnose each wheel speed sensor individually.

A possible cause of this DTC is electrical noise on the wheel speed sensor harness wiring. Electrical noise could result from the wheel speed sensor wires being routed to close to high energy ignition system components, such as spark plug wires.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the wheel speed sensor for the proper resistance value.
2. 4: This step ensures that the wheel speed sensor generates the proper voltage.

DTC C0035-C0051

The inlet and outlet valve solenoid circuits are supplied with battery power when the ignition is in the ON position. The EBCM controls the valve functions by grounding the circuit when necessary.

This diagnostic procedure supports the following DTCs

1. DTC C0060 Left Front ABS Solenoid 1 Circuit Malfunction
2. DTC C0065 Left Front ABS Solenoid 2 Circuit Malfunction
3. DTC C0070 Right Front ABS Solenoid 1 Circuit Malfunction
4. DTC C0075 Right Front ABS Solenoid 2 Circuit Malfunction
5. DTC C0080 Left Rear ABS Solenoid 1 Circuit Malfunction
6. DTC C0085 Left Rear ABS Solenoid 2 Circuit Malfunction
7. DTC C0090 Right Rear ABS Solenoid 1 Circuit Malfunction
8. DTC C0095 Right Rear ABS Solenoid 2 Circuit Malfunction

Conditions for Running the DTC

1. The DTC can set anytime the ignition switch is in the ON position.
2. The DTC can set when the vehicle speed is greater then 6 km/h (4 mph) and the brake pedal is not applied.
3. The DTC can set when the vehicle speed is greater then 15 km/h (9 mph) and the brake pedal is applied.

Conditions for Setting the DTC

The DTC will set when the EBCM detects one of the following internal to the EBCM only

1. An open in the solenoid coil or circuit.
2. A short to ground in the solenoid coil or circuit.
3. A short to voltage in the solenoid coil or circuit.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the ABS/traction control system (TCS)/vehicle stability enhancement system (VSES)/dynamic rear proportion (DRP) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator could turn ON.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

The solenoid valve circuit and the solenoid coil are internal to the EBCM. No part of the solenoid circuit is diagnosable external to the EBCM. The DTC sets when there is a malfunction in the solenoid circuit internal to the EBCM only.

The number below refers to step number on the diagnostic table.

1. 2: This step determines if the DTC is current.

DTC C0060-C0095

The pump motor is an integral part of the BPMV, while the pump motor relay is integral to the EBCM. The pump motor relay is not engaged during normal system operation. When ABS or TCS operation is required the EBCM activates the pump motor relay and battery power is provided to the pump motor.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC C0110 Pump Motor Circuit Malfunction

1. The ignition switch is in the ON position.
2. Initialization is complete.

1. Pump motor voltage is not present 60 milliseconds after activation of the pump motor relay.
2. Pump motor voltage is present for more than 2.5 seconds with no activation of the pump motor relay.
3. Pump motor voltage is not present for 40 milliseconds after the pump motor relay is commanded off.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the ABS/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator could turn ON.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

1. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
2. Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: Backed out terminals Improper mating Broken locks Improperly formed or damaged terminals Poor terminal-to-wiring connections Physical damage to the wiring harness
3. The following conditions may cause an intermittent malfunction: A poor connection Rubbed-through wire insulation A broken wire inside the insulation
4. If an intermittent malfunction exists refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) in Wiring Systems.

The number below refers to the step number on the diagnostic table.

1. 3: This step tests the pump motor circuits of the brake pressure modulator valve (BPMV) for a short to the housing of the BPMV. The wiring from the BPMV to the EBCM should not be repaired.

DTC C0110

The solenoid valve relay supplies power to the solenoid valve coils in the EBCM. The solenoid valve relay, located in the EBCM, is activated whenever the ignition switch is in the RUN position and no faults are present. The solenoid valve relay remains engaged until the ignition is turned OFF or a failure is detected.

This diagnostic procedure supports the following DTC

DTC C0121 Valve Relay Circuit Malfunction

The ignition switch is in the ON position.

1. DTC C0121 will set anytime the solenoid valve relay is commanded on and the EBCM does not see battery voltage at the solenoid valves.
2. DTC C0121 will set anytime the EBCM commands the solenoid valve relay off and battery voltage is still present at the solenoid valves.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the antilock brake system (ABS)/traction control system (TCS)/vehicle stability enhancement system (VSES)/dynamic rear proportion (DRP) for the duration of the ignition cycle.
2. A malfunction DTC is set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator could turn ON.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

1. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
2. Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: Backed out terminals Improper mating Broken locks Improperly formed or damaged terminals Poor terminal-to-wiring connections Physical damage to the wiring harness
3. The following conditions may cause an intermittent malfunction: A poor connection Rubbed-through wire insulation A broken wire inside the insulation
4. If an intermittent malfunction exists, refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) in Wiring Systems.
5. The solenoid valve relay is an integral part of the EBCM and is not serviced separately.

The number below refers to step number on the diagnostic table.

1. 2: This step determines if the DTC is current.

DTC C0121

The electronic brake control module (EBCM) uses input from the brake pressure sensor for more accurate control during a vehicle stability enhancement system (VSES) event.

This diagnostic procedure supports the following DTC

DTC C0131 Antilock Brake System (ABS)/Traction Control System (TCS) Pressure Circuit

1. DTC C0870 is not set.
2. The ignition is ON.
3. The vehicle speed is greater than 40 km/h (24 mph).

Voltage at the pressure sensor signal output to the EBCM falls outside the 0.25-4.75 volts range for more than 100 milliseconds.

If equipped, the following actions occur

1. The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/VSES for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator could turn ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool, clear DTC function.

1. A thorough inspection of the wiring system and connectors should be performed. Failure to carefully and fully inspect the wiring system and connectors may result in misdiagnosis which may result in replacing good parts and the reappearance of the malfunction.
2. Inspection for poor connections, broken insulation or a wire that is broken inside the insulation.
3. If an intermittent malfunction exists refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for specified voltage on the brake pressure signal circuit.
2. 3: This step checks to see if voltage was below specified voltage.
3. 4: This step checks to see if voltage was below specified voltage.
4. 5: This step checks to see if voltage was above specified voltage of the 5-volt reference.
5. 6: This step tests for a short to ground in the 5-volt reference circuit.
6. 7: This step tests for a short to voltage in the 5-volt reference circuit.
7. 8: This step tests for a short to ground, a high resistance or an open in the 5-volt reference circuit.
8. 9: This step tests for a short to voltage, a high resistance or an open in the brake pressure sensor signal circuit.
9. 10: This step tests for a high resistance or an open in the ground circuit of the brake pressure sensor.
10. 11: This step checks the brake pressure sensor connector for poor connections.
11. 12: This step checks the EBCM connector for poor connections.

DTC C0131

During calibration of the offset of the pressure sensor signal, the pressure sensor signal offset value must be in the range of 1-15 bar (1-434 psi).

The pressure sensor is also monitored for sensitivity via a correlation between estimated vehicle deceleration and the pressure sensor signal. This is monitored over the course of numerous straight line non-ABS braking stops.

This diagnostic procedure supports the following DTC

DTC C0132 Antilock Brake System (ABS)/Traction Control System (TCS) Pressure Circuit Range/Performance

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

1. The sensor signal offset value is out of range for more than 1 second.
2. The brake pedal is not applied.
3. The ABS pump is not ON.
4. The brake pressure sensor sensitivity is outside a predetermined range.
5. The brake pressure sensor indicates low brake fluid pressure and the brake pedal position sensor indicates brakes applied.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the ABS/TCS/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator could turn ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool

1. A malfunctioning pressure sensor
2. A malfunctioning EBCM
3. Test the brake pedal position sensor (BPPS) for proper operation and adjustment. A improperly adjusted BPPS will set the DTC.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for DTCs set in the body control module (BCM) lighting systems for a malfunctioning BPPS.
2. 3: This step tests for specified voltage on the brake pressure signal circuit.
3. 4: This step checks to see if voltage was below specified voltage.
4. 5: This step checks to see if voltage was above specified voltage.
5. 6: This step checks to see if voltage was above specified voltage of 5-volt reference.
6. 7: This step checks to see if 5-volt reference from EBCM is 5 volts.
7. 8: This step checks to see if resistance of ground circuit is less than 5 ohms.
8. 9: This step tests for short to voltage in the 5-volt reference circuit.
9. 10: This step tests for a short to ground, a high resistance or an open in the 5-volt reference circuit.
10. 11: This step tests for a short to voltage in the brake pressure sensor signal circuit.
11. 12: This step tests for a high resistance or an open in the ground circuit.
12. 13: This step checks to brake pressure sensor connector for poor connections.
13. 14: This step checks to EBCM connector for poor connections.

DTC C0132

The isolation and prime valve solenoid circuits are supplied with battery power when the ignition is in the ON position. The EBCM controls the valve functions by grounding the circuit when necessary.

This diagnostic procedure supports the following DTCs

1. DTC C0141 Left Traction Control System (TCS) Solenoid/Motor {single or 1} Circuit
2. DTC C0146 Left Traction Control System (TCS) Solenoid/Motor 2 Circuit
3. DTC C0151 Right Traction Control System (TCS) Solenoid/Motor {single or 1} Circuit
4. DTC C0156 Right Traction Control System (TCS) Solenoid/Motor 2 Circuit

1. The ignition switch is in the ON position.
2. The DTC can be set after system initialization.

The DTC will set when the EBCM detects one of the following internal to the EBCM only

1. An open in the solenoid coil or circuit.
2. A short to ground in the solenoid coil or circuit.
3. A short to voltage in the solenoid coil or circuit.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the antilock brake system (ABS)/traction control system (TCS)/vehicle stability enhancement system (VSES)/dynamic rear proportion (DRP) for the duration of the ignition cycle.
2. A malfunction DTC is set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator could turn ON.

1. Condition for DTC is no longer present and scan tool clear DTC function is used.
2. 100 ignition cycles pass with no DTCs detected.

The solenoid valve circuit and the solenoid coil are internal to the EBCM. No part of the solenoid circuit is diagnosable external to the EBCM. The DTC sets when there is a malfunction in the solenoid circuit internal to the EBCM only.

The number below refers to the step number on the diagnostic table.

1. 2: This step determines if the DTC is current.

DTC C0141-C0156

The brake pedal position sensor (BPPS) is used by the body control module (BCM) to determine the brake pedal angle for various electrical components. The BPPS is a potentiometer type sensor with 3 circuits: a 10-volt reference circuit, a low reference circuit, a brake apply sensor signal circuit. The BCM provides the BPPS with 10 volts on the 10-volt reference circuit and a ground on the low reference circuit. Application of the BPPS rotate from the closed brake pedal position to the full apply position provides the BCM with a signal voltage from less than 1 volt to greater than 9 volts through the BPPS signal circuit. When the conditions for running this DTC are met, the BCM will use the brake fluid pressure sensor to determine if the predicted operating range of the BPPS is correct. If the BCM detects the BPPS voltage is out of the predicted range, the BCM will send a class 2 message to the electronic brake control module (EBCM) to set DTC C0161. The EBCM will set DTC C0131 or C0132 for a brake fluid pressure sensor fault. The BCM will set DTC C0277, C0278 or C0870 if a fault is detected in the BPPS.

This diagnostic procedure supports the following DTCs

1. DTC C0161 ABS/TCS Brake Switch Circuit Malfunction
2. DTC C0277 Brake Pedal Position Sensor Circuit
3. DTC C0278 Brake Pedal Position Sensor Not Calibrated
4. DTC C0870 Device Voltage Reference Output {single or 1} Circuit

1. The ignition switch is ON.
2. The DTC can be set after system initialization.

1. The BCM detects a failure in the BPPS system.
2. The BCM receives a signal from the sensor indicating the brake pedal is applied, the driver commanded throttle and brake fluid pressure sensor is less then 5 bars (73 psi) for 60 seconds.
3. The BCM receives a signal from the sensor indicating the brake is not applied and the brake fluid pressure sensor is greater then 15 bars (218 psi) for 1 second.

If equipped, the following actions occur

1. The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

It is possible to set DTC C0161 if the vehicle is driven with the brake and the accelerator pedal applied at the same time for more than 60 seconds.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step checks if there is other DTCs that can cause the BPPS failure.
2. 7: This step checks to see if the DTC will reset as current.

DTC C0161

The vehicle stability enhancement system (VSES) uses the lateral accelerometer input when calculating the desired yaw rate. The usable output voltage range for the lateral accelerometer is 0.25-4.75 volts.

The lateral accelerometer sensor bias compensates for sensor mounting alignment errors and electronic signal errors.

This diagnostic procedure supports the following DTC

DTC C0186 Lateral Accelerometer Circuit

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

Voltage at the lateral accelerometer signal output to the electronic brake control module (EBCM) falls outside the 0.25-4.75 volt range for more than 100 milliseconds.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/VSES for the duration of the ignition cycle.
2. A malfunction DTC is set.
3. The antilock brake system (ABS) indicator turns ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool

1. A thorough inspection of the wiring system and connectors be performed. Failure to carefully and fully inspect the wiring system and connectors may result in misdiagnosis which may result in replacing good parts and the reappearance of the malfunction.
2. Inspection for poor connections, broken insulation or a wire that is broken inside the insulation.
3. If an intermittent malfunction exists, refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for specified voltage on the lateral accelerometer signal circuit.
2. 3: This step tests for B+ voltage on yaw/lateral accelerometer sensor.
3. 4: This step tests the ignition circuit for a high resistance or open.
4. 5: This step checks to see if the voltage was below or above the specified voltage.
5. 6: This step checks to see if the voltage was above the specified voltage.
6. 7: This step checks to see if the voltage was below the specified voltage.
7. 8: This step checks to see if the voltage was above the specified voltage.
8. 9: This step checks to see if the resistance of the ground circuit is less than 5 ohms.
9. 10: This step tests for a short to voltage on the 5-volt reference circuit.
10. 11: This step tests for a short to ground, a high resistance or an open in the 5-volt reference circuit.
11. 12: This step tests for a short to ground, a high resistance or an open in the lateral accelerometer signal circuit.
12. 13: This step tests for a short to voltage in the lateral accelerometer signal circuit.
13. 14: This step tests for a high resistance or an open in the ground circuit.
14. 15: This step checks the yaw/lateral accelerometer sensor connector for poor connections.
15. 16: This step checks the EBCM connector for poor connections.

DTC C0186

The vehicle stability enhancement system (VSES) uses the lateral accelerometer input when calculating the desired yaw rate. The usable output voltage range for the lateral accelerometer 0.25-4.75 volts. The scan tool will report zero lateral acceleration as 2.5 volts with no sensor bias present.

The lateral accelerometer sensor bias compensates for sensor mounting alignment errors and electronic signal errors.

This diagnostic procedure supports the following DTC

DTC C0187 Lateral Accelerometer Circuit Range/Performance

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

1. A reference lateral acceleration from the data of the yaw rate sensor, wheel speed sensors and steering angle sensor is used to test the lateral accelerometer signal. If during stable driving conditions, the lateral accelerometer signal becomes larger than 0.26 g, the electronic brake control module (EBCM) controller will disregard the signal so that a false EBCM intervention is prevented. A malfunction is detected if this condition continues for more than 2 seconds.
2. Under normal driving conditions, the long time filtered driving direction is straight ahead. The long time filtered lateral accelerometer value is called the offset. If the offset value is higher than 0.23 g, a malfunction is detected. Malfunction time depends on driving distance, vehicle speed and the amount of malfunctioning later accelerometer signal.
3. The lateral accelerometer signal is limited to an electrical stop of 1.8 g. If the lateral accelerometer signal is greater than 1.5 g for more than 500 milliseconds, a malfunction is detected.
4. At a standstill, the range of the lateral accelerometer signal is less than 0.7 g. If the lateral accelerometer signal is greater than 0.7 g at standstill, a malfunction is detected.
5. Lateral accelerometer signal cannot change rapidly under normal driving conditions. If the lateral accelerometer signal is changing faster than 55 g per second, a malfunction is detected.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/VSES for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The antilock brake system (ABS) indicator turns ON.
4. The Stability Off indicator turns ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool

1. Find out from the customer under what condition was the DTC set. This information will help to duplicate the failure.
2. Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
3. During diagnosis, park the vehicle on a level surface.
4. Check for malfunctioning EBCM and lateral accelerometer.
5. The snapshot function on the scan tool can help find an intermittent DTC.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step checks to see if steering angle sensor is centered.
2. 3: This step checks for specified voltage on the lateral accelerometer signal circuit.
3. 4: This step checks for specified voltage on the yaw rate signal circuit.

DTC C0187

The vehicle stability enhancement system (VSES) is activated by the electronic brake control module (EBCM) calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle's yaw motion by applying differential braking to the wheels.

To correct for oversteer, differential braking is used on the left front or right front wheel brake. To correct for understeer, differential braking is used on the left rear or right rear wheel brake.

This diagnostic procedure supports the following DTC

DTC C0196 Yaw Rate Circuit

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

The EBCM performs different tests to detect a DTC condition. A malfunction is detected when the yaw rate sensor signal input voltage is less than 0.225 volt or greater than 4.775 volts for more than 100 milliseconds.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/VSES for the duration of the ignition cycle.
2. A malfunction DTC is set.
3. The antilock brake system (ABS) indicator turns ON.
4. The Stability Off indicator turns ON.

1. Using a scan tool
2. The DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

The following conditions may cause a malfunction

1. An open in the yaw rate signal circuit
2. A short to ground in the yaw rate signal circuit
3. A short to voltage in the yaw rate signal circuit
4. An open in the yaw rate ground circuit
5. An open in ignition voltage circuit
6. A malfunctioning vehicle yaw/lateral accelerometer sensor
7. A malfunctioning EBCM

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for specified voltage on the yaw rate signal circuit.
2. 3: This step checks the voltage between the ignition and ground circuit for a specified value.
3. 4: This step checks the voltage between the ignition and ground circuit for a specified value.
4. 5: This step checks to see if the voltage was above the specified voltage.
5. 6: This step checks to see if the voltage was below the specified voltage.
6. 7: This step checks to see if the EBCM 5-volt reference signal is within the specified limit.
7. 8: This step checks to see if the voltage was above the specified voltage.
8. 9: This step checks to see if the resistance of the ground circuit is less than 5 ohms.
9. 10: This step tests for a short to voltage on the 5-volt reference circuit.
10. 11: This step tests for a short to ground, a high resistance or an open in the 5-volt reference circuit.
11. 12: This step tests for a short to voltage in the yaw rate signal circuit.
12. 13: This step tests for a short to ground, a high resistance or an open in the yaw rate signal circuit.
13. 14: This step tests for a high resistance or an open in the ground circuit.
14. 15: This step checks the EBCM connector for poor connections.
15. 16: This step checks the yaw/lateral accelerometer sensor connector for poor connections.

DTC C0196

The electronic brake control module (EBCM) triggers a yaw rate sensor test every 40 milliseconds and switches the sensor into test mode. The EBCM sends a test signal to the sensor via the test circuit. When the test is run, the measured yaw rate from the sensor to the EBCM must be in the range of 25 degrees per second that is greater or less then 7 degrees per second. At standstill, the vehicle yaw rate is zero. The yaw rate signal at standstill is called the offset. If calibration at standstill is not possible, a quick calibration during driving is done. The measured yaw rate is calibrated to a calculated reference yaw rate signal. Yaw rate sensor sensitivity is estimated by comparison of the reference yaw rate and the measured yaw rate during cornering.

Steering angle centering is the process by which the EBCM calibrates the steering sensor output so that the output reads zero when the steering wheel is centered. The vehicle stability enhancement system (VSES) steering angle sensor centering process is performed manually.

This diagnostic procedure supports the following DTC

DTC C0197 Yaw Rate Circuit Range/Performance

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

A malfunction is detected if one or more of the following conditions exist

1. The yaw rate sensor signal is out of range for 220-420 milliseconds.
2. The yaw rate sensor signal at standstill, which is called the offset, is outside the allowed range that is greater or less then 8 degrees per second.
3. The sensor sensitivity which is estimated by comparing the reference yaw rate and the measured yaw rate during cornering, is outside a predetermined range.
4. The yaw rate is changing at a rate greater than 6-23 degrees per second per 40 milliseconds.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/VSES for the duration of the ignition cycle.
2. A malfunction DTC is set.
3. The antilock brake system (ABS) indicator turns ON.
4. The Stability Off indicator turns ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool, clear the DTC function.

The following conditions may cause a malfunction

1. A malfunctioning lateral accelerometer
2. A malfunctioning EBCM

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step checks to see if the steering angle sensor is centered.
2. 3: This step checks for specified voltage on the lateral accelerometer signal circuit.
3. 4: This step checks for specified voltage on the yaw rate signal circuit.

DTC C0197

The RPM signal circuit provides the EBCM with an indication of engine RPM to help determine TCS control methods and rates when a TCS event takes place.

This diagnostic procedure supports the following DTC

DTC C0236 Traction Control System (TCS) Engine RPM Signal Circuit

1. The ignition switch is ON and the engine running.
2. After 2 seconds starting and if there is a undervoltage condition.

The EBCM does not received an RPM input signal after 1 second, after the engine has been started.

If equipped, the following actions occur

1. A malfunction DTC is stored.
2. The TCS is disabled. The ABS remains functional.

1. The condition for DTC is no longer present and the scan tool Clear DTCs function is used.
2. 100 ignition cycles have passed with no DTC(s) detected.

Perform a thorough inspection of the wiring. Perform a thorough inspection of the connectors. Failure to carefully and fully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis causes part replacement with reappearance of the malfunction.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: If the instrument panel (I/P) tachometer is working properly, the cause of the malfunction is most likely between the powertrain control module (PCM) and the electronic brake control module (EBCM) or the EBCM itself.
2. 9: At this point, the PCM is likely causing the malfunction. Refer to the on-board diagnostic (OBD) system check.

DTC C0236

The PCM monitors various parameters and will not allow traction control operation if any parameter falls below a specified value.

This diagnostic procedure supports the following DTC

DTC C0240 Powertrain Control Module (PCM) Traction Control Not Allowed

The ignition is ON.

The PCM detects a malfunction and then causes TCS shut down until the malfunction has been corrected.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A DTC C0240 is stored.
3. The TCS is disabled.
4. The Stability Off indicator is turned ON.
5. If the TCS is again allowed to function, the indicator will be turned OFF, but the DTC will be stored.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

The number below refers to the step number on the diagnostic table.

1. 4: This step checks if DTC C0240 resets.

DTC C0240

The EBCM and the PCM simultaneously control the traction control. The EBCM sends a Requested Torque message via a pulse width modulated (PWM) signal to the PCM. The duty cycle of the signal is used to determine how much engine torque the EBCM is requesting the PCM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal should be at 90 percent when traction control is not active and at lower values during traction control activations. The PCM supplies the pull up voltage that the EBCM switches to ground to create the signal.

This diagnostic procedure supports the following DTCs

1. DTC C0241 Powertrain Control Module (PCM) Indicated Requested Torque Malfunction
2. DTC P0856 Traction Control Torque Request Circuit

The ignition is ON.

The PCM diagnoses the requested torque PWM signal circuit and sends a class 2 serial data message to the EBCM indicating a fault is present. A fault exists in the circuit if the PCM detects one of the following conditions

1. The requested torque PWM signal is less than 5 percent duty cycle or greater than 95 percent duty cycle.
2. The requested torque PWM signal is not present for 10 seconds.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The Stability Off indicator turns ON.
4. The antilock brake system (ABS) remains functional.

1. The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
2. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: Use the scan tool in order to determine if the requested torque signal has a valid duty cycle.
2. 4: Measure the requested torque signal in order to determine if the signal has a valid duty cycle.
3. 5: Measure the requested torque signal in order to determine if the signal has a valid frequency.
4. 11: This vehicle is equipped with a PCM which uses an electrically erasable programmable read only memory (EEPROM). When replacing the PCM, the replacement PCM must be programmed.

DTC C0241 or P0856

Traction Control is simultaneously controlled by the EBCM and the PCM. The PCM sends a DELIVERED TORQUE message via a Pulse Width Modulated (PWM) signal to the EBCM confirming the delivered torque level for proper Traction Control system operation. The EBCM supplies the pull up voltage.

This diagnostic procedure supports the following DTCs

1. DTC C0244 Pulse Width Modulated (PWM) Delivered Torque
2. DTC P1689 Traction Control Delivered Torque Output Circuit

1. The ignition switch is ON.
2. The DTC can be set after system initialization.

DTC C0244 can be set anytime when ignition voltage is present. A malfunction exists if the PWM signal is out of range or no signal is received for a period of 2 seconds.

If equipped, the following actions occur

1. The electronic brake control module (EBCM) disables the traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The Traction Control Off is turned ON. The ABS remains functional.
4. The Stability Off indicator is turned ON.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

1. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
2. If an intermittent malfunction exists refer to «Checking Aftermarket Accessories»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__checking-aftermarket-accessories) in Wiring Systems.
3. Possible causes for DTC C0244 to set: Open in the Torque Delivered Control circuit. Torque Delivered Control circuit shorted to ground or voltage. Communication frequency problem. Communication duty cycle problem. Torque Delivered Control circuit has a wiring problem, terminal corrosion or poor connections. EBCM not receiving information from the PCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: Use the scan tool in order to determine if the delivered torque signal has a valid duty cycle.
2. 9: This vehicle is equipped with a powertrain control module (PCM) which uses an electrically erasable programmable read only memory (EEPROM). When replacing the PCM, the replacement PCM must be programmed.

DTC C0244 or P1689

The speed sensors used on the front of this vehicle are multiple pole and the rear uses a single pole magnetic pickup. This sensor produces an AC signal that the EBCM uses the frequency from to calculate the wheel speed.

This diagnostic procedure supports the following DTC

DTC C0245 Wheel Speed Sensor Frequency Error

1. The ignition switch is ON.
2. The DTC can be set after system initialization.

1. The electronic brake control module (EBCM) detects a deviation between the left and right rear wheel speeds of greater than 6 km/h (3.75 mph) at a vehicle speed of less than 100 km/h (62 mph) on vehicles equipped with traction control module (TCS).
2. The EBCM detects a deviation between the left and right front wheel speeds of greater than 10 km/h (6.25 mph) at a vehicle speed of less than 100 km/h (62 mph).
3. The EBCM detects a deviation between the left and right rear wheel speeds of greater than 6 percent of the vehicle speed at greater than 100 km/h (62 mph) on vehicles equipped with TCS.
4. The EBCM detects a deviation between the left and right front wheel speeds of greater than 4 km/h plus 6 percent of the vehicle speed at greater than 100 km/h (62 mph).

This DTC will set when the EBCM cannot specifically identify which wheel speed sensor (WSS) is causing the malfunction. If the EBCM can identify the specific WSS causing the malfunction, DTC C0245 will become a history DTC and the DTC associated with the sensor DTC C0036, DTC C0041, DTC C0046, DTC C0051 or DTC C0056 will be set concurrent with DTC C0245.

If equipped, the following actions occur

1. The EBCM disables the ABS/TCS/vehicle stability enhancement system (VSES)/dynamic rear proportion (DRP) and magnetic steering variable assist (MSVA) for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.
5. The red BRAKE warning indicator turns ON.

1. The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
2. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

1. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
2. Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: Backed out terminals Improper mating Broken locks Improperly formed or damaged terminals Poor terminal-to-wiring connections Physical damage to the wiring harness
3. The following conditions may cause an intermittent malfunction: A poor connection Rubbed-through wire insulation A broken wire inside the insulation
4. If the customer's comments reflect that the amber ABS/TCS indicator is on only during moist environmental conditions (rain, snow, vehicle wash), inspect all the wheel speed sensor circuitry for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure: Spray the suspected area with a five percent saltwater solution. Add two teaspoons of salt to twelve ounces of water to make a five percent saltwater solution. Test drive the vehicle over various road surfaces (bumps, turns, etc.) above 40 km/h (25 mph) for at least 30 seconds. If the DTC returns, replace the suspected harness.
5. If an intermittent malfunction exists refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) in Wiring Systems.

The numbers below refer to step numbers on the diagnostic table.

1. 2: If DTC C0245 is a history code, this step checks if a specific wheel speed circuit malfunction DTC is set concurrently with DTC C0245.
2. 7: This step checks if the WSS harness is routed in close proximity to the spark plug wires.
3. 9: In this step, if the scan tool can record any erroneous WSS signals, diagnose that sensors first.

DTC C0245

The vehicle stability enhancement system (VSES) is activated by the electronic brake control module (EBCM) calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle yaw motion by applying differential braking to the left or right wheels.

This diagnostic procedure supports the following DTC

DTC C0252 Vehicle Stability Enhancement System (VSES) Sensors Uncorrelated

1. The steer angle has been centered.
2. The VSES is active.
3. The direction, understeer or oversteer, of the yaw rate error has not changed.
4. The lateral acceleration is less than 0.5 grams.

One of the following conditions occur

1. The VSES is engaged for 10 seconds with the yaw rate error always in either understeer or oversteer. Under this condition, this DTC will set by itself.
2. The yaw rate error is greater than 10 degrees/second for 5 seconds.

If equipped, the following actions occur

1. The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/VSES and for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability Off indicator turns ON.

1. The condition for the DTC is no longer present, the DTC is not current and you used the scan tool Clear DTC function.
2. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

1. During diagnosis, park the vehicle on a level surface.
2. Inspect the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
3. Find out from the customer the conditions under which the DTC was set. This information will help to duplicate the failure.
4. The Snapshot function on the scan tool can help find an intermittent DTC.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This checks to see if DTC C0252 is set.
2. 3: This step checks to see if the DTC C0252 resets.
3. 4: This step checks to see if VSES data list parameters are correct.
4. 5: This step checks the components harness connectors for poor connections.

DTC C0252

Steer angle centering is the process by which the electronic brake control module (EBCM) calibrates the steering sensor output so that the output reads zero when the steering wheel is centered.

This diagnostic procedure supports the following DTC

DTC C0253 Centering Error

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

If the steering angle sensor controller area network (CAN) message or the EBCM indicates an uncentered sensor

If equipped, the following actions occur

1. The EBCM disables the ABS/traction control system (TCS)/vehicle stability enhancement system (VSES) and for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The ABS indicator turns ON.
4. The Stability indicator turns ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool.
4. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Perform the steering angle sensor centering procedure.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step checks to see if other DTC is set.
2. 3: This step checks to see if steering angle sensor is centered.

DTC C0253

Under normal driving conditions, the electronic brake control module (EBCM) monitors the steering angle sensor inputs to see if the steering wheel is moving. If the steering wheel is not moving for a set period of time, the EBCM assumes the vehicle is going in a straight line. At this point, the EBCM looks at the steering angle sensor inputs and considers the degree angle to be zero. This is called the offset value.

Steer angle centering is the process by which the EBCM calibrates the steering sensor output so that the output reads zero when the steering wheel is centered.

This diagnostic procedure supports the following DTC

DTC C0710 Steering Position Signal

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

A malfunction is detected if one or more of the following conditions exist

1. The steering angle sensor detects an internal malfunction and sends a controller area network (CAN) message to the EBCM.
2. If the offset value is higher than 15 degrees, a malfunction is detected. Malfunction time depends on driving distance, vehicle speed and the amount of malfunctioning steering angle signal.
3. Rapid changes of the steering angle sensor signal cannot occur under normal driving conditions. If the signal change is higher than 2,000 degrees per second or steering angle acceleration is higher than 37,500 degrees per second squared, a malfunction is detected.
4. A reference steering angle signal based on a vehicle model is used to check the actual steering angle. If the measured steering angle varies from the reference steering angle by more than a predetermined value, a malfunction is detected.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/vehicle stability enhancement system (VSES) and for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The Stability Off indicator turns ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool
4. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Perform the steering angle sensor centering procedure.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This test checks to see if any other DTC is set.
2. 3: This test checks to see if steering angle sensor is centered.

DTC C0710

The brake pressure sensor reference voltage is monitored for an over or under voltage condition.

This diagnostic procedure supports the following DTC

DTC C0870 Device Voltage Reference Output {single or 1} Circuit

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

A malfunction is detected if the supply voltage is above 5.6 volts or below 4.4 volts for more than 60 milliseconds.

1. A malfunction DTC is set.
2. The ABS, traction control system (TCS) and vehicle stability enhancement system (VSES) are disabled.
3. The ABS, SERVICE VEHICLE SOON and Stability Off lamp indicators are ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool
4. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Possible causes of this DTC are the following conditions

1. An open in the pressure sensor supply voltage circuit
2. A short to ground in the pressure sensor supply voltage circuit
3. A short to B+ in the pressure sensor supply voltage circuit

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for specified voltage on the brake pressure signal circuit.
2. 3: This step checks to see if the brake pressure signal circuit voltage was below specified voltage.
3. 4: This step checks to see if the brake pressure signal circuit voltage was above specified voltage.
4. 5: This step tests for a short to ground in the 5-volt reference circuit of the brake pressure sensor.
5. 6: This step tests for a short to voltage in the 5-volt reference circuit of the brake pressure sensor.
6. 7: This step tests for a high resistance or an open in the ground circuit of the brake pressure sensor.
7. 8: This step checks the brake pressure sensor connector for poor connections.
8. 9: This step checks the EBCM connector for poor connections.

DTC C0870

The yaw rate sensor reference voltage is monitored for an over or under voltage condition.

This diagnostic procedure supports the following DTC

DTC C0875 Device Voltage Reference Input 2 Circuit

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

A malfunction is detected if the supply voltage is above 2.9 volts or below 2.1 volts for more than 200 milliseconds.

1. A malfunction DTC is set.
2. The traction control system (TCS) and vehicle stability enhancement system (VSES) are disabled.
3. Stability Off and SERVICE VEHICLE SOON lamp indicators are ON.

1. The condition for the DTC is no longer present.
2. A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
3. Using a scan tool
4. The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Possible causes of this DTC are the following conditions

1. An open in the yaw rate sensor supply voltage circuit
2. A short to ground in the yaw rate sensor supply voltage circuit
3. A short to B+ in the yaw rate sensor supply voltage circuit

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for specified voltage on the 5-volt reference signal circuit.
2. 3: This step checks to see if voltage was below specified voltage.
3. 4: This step checks to see if voltage was above specified voltage.
4. 5: This step tests for a short to ground in the 5-volt reference circuit of the yaw/lateral accelerometer sensor.
5. 6: This step tests for a short to voltage in the 5-volt reference circuit of the yaw/lateral accelerometer sensor.
6. 7: This step tests for a high resistance or an open in the ground circuit of the yaw/lateral accelerometer sensor.
7. 8: This step checks the yaw/lateral accelerometer sensor connector for poor connections.
8. 9: This step checks the EBCM connector for poor connections.

DTC C0875

The controller area network (CAN) serial data circuit is a high speed serial data bus used to communicate information between the steering angle sensor and the electronic brake control module (EBCM). When the ignition switch is turned to the ON position, the module and the steering angle sensor begin to transmit data between each other.

The CAN bus circuit is monitored continuously after the ignition switch is turned to the ON position.

This diagnostic procedure supports the following DTC

DTC U1650 Steering Wheel Sensor CAN Malfunction

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

Line interruptions are detected by the CAN message monitor.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/vehicle stability enhancement system (VSES) and for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The Stability indicator turns ON.

1. The condition for the DTC is no longer present.
2. Using a scan tool clear, DTC function.
3. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Possible causes of this DTC are as follows

1. CAN HI and CAN LO circuits shorted together
2. CAN HI or CAN LO circuit shorted to ground
3. CAN HI or CAN LO circuit shorted to voltage

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for a short to ground between the CAN HI and CAN LO circuits.
2. 3: This step tests the CAN HI and CAN LO circuits for a short together.
3. 4: This test checks to see if steering angle sensor is centered.

DTC U1650

The electronic brake control module (EBCM) monitors the received messages from the steering angle sensor for corruption or for missing messages.

This diagnostic procedure supports the following DTC

DTC U1651 Steering Wheel Sensor Malfunction

1. The ignition is ON.
2. The vehicle speed is greater than 40 km/h (25 mph).

The EBCM receives a corrupt or a missing message after 100 milliseconds.

If equipped, the following actions occur

1. The EBCM disables the traction control system (TCS)/vehicle stability enhancement system (VSES) and for the duration of the ignition cycle.
2. A malfunction DTC will set.
3. The Stability Off indicator turns ON.

1. The condition for the DTC is no longer present.
2. Using a scan tool.
3. The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Possible causes of this DTC are as follows

1. An open in the CAN HI or CAN LO circuit
2. An open in the ignition circuit
3. An open in the ground circuit
4. A malfunctioning steering angle sensor
5. A malfunctioning EBCM

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests the ignition circuit for an open.
2. 3: This step checks the ground circuit for an open.
3. 4: This step tests the CAN HI circuit for an open.
4. 5: This step tests the CAN LO circuit for an open.
5. 6: This step checks the steering angle sensor connector for poor connections.

DTC U1651

Symptoms - Antilock Brake System

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to «ABS Description and Operation»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the antilock brake system. Refer to «Checking Aftermarket Accessories»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Inspect the master cylinder reservoir for the proper brake fluid level.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. 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. «ABS Indicator Always On»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system)
2. «ABS Indicator Inoperative»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system)
3. «Stability System Disabled Indicator Always On»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system)
4. «Traction Off Indicator Always On»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system)
5. «Traction Off Indicator Inoperative»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system)

The instrument panel cluster (IPC) turns the antilock brake system (ABS) indicator ON during the IPC bulb check for approximately 3 seconds when the ignition switch is turned to the ON position. If the electronic brake control module (EBCM) DTC, the EBCM sends the IPC the command to turn the ABS indicator ON.

The number below refers to step number on the diagnostic table.

1. 2: This step checks if the IPC has the ability to turn the ABS indicator OFF or if the EBCM is sending an incorrect command to turn the ABS indicator ON.

ABS Indicator Always On

The instrument panel cluster (IPC) turns the antilock brake system (ABS) indicator ON during the IPC bulb check for approximately 3 seconds when the ignition switch is turned to the ON position. If the electronic brake control module (EBCM) sets a DTC, the EBCM sends the IPC the command to turn the ABS indicator ON.

The number below refers to step number on the diagnostic table.

1. 2: This step checks if the IPC has the ability to turn the ABS Indicator ON.

ABS Indicator Inoperative

The stability system disable indicator is controlled by the instrument cluster via class 2 serial data messages from the electronic brake control module (EBCM). When the instrument cluster sees a class 2 message from the EBCM that tells the instrument panel cluster (IPC) that the stability system is malfunctioning, the EBCM then disables vehicle stability enhancement system (VSES) and traction control system (TCS) and sends a message to the instrument cluster to turn the stability system disable indicator always on and TCS indicators ON. Each time the ignition is cycled from OFF to ON, the VSES is enabled

The following conditions will cause the VSES/TCS indicators to illuminate

1. The EBCM has disabled the VSES/TCS due to a DTC.
2. The instrument cluster bulb check-When the ignition switch is turned to ON, the VSES/TCS indicators will turn ON for approximately 3 seconds and then turn OFF.

Stability System Disabled Indicator Always On

The TRAC OFF indicator is controlled by the instrument cluster via class 2 serial data messages from the electronic brake control module (EBCM). When the body control module (BCM) sees the traction control switch input grounded through the momentary traction control switch, it sends a class 2 message to the EBCM that tells the EBCM that the traction control switch has been pressed. The EBCM then disables traction control and sends a message to the instrument cluster to turn the TRAC OFF indicator ON. Each time the ignition is cycled from OFF to ON, the traction control system is enabled.

The following conditions will cause the TRAC OFF indicator to illuminate

1. The EBCM has disabled the traction control system (TCS) due to a DTC.
2. The driver manually disabling the TCS via the traction control switch
3. The instrument cluster bulb check-When the ignition switch is turned to ON, the TRAC OFF indicator will turn ON for approximately 3 seconds and then turn OFF.

1. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
2. Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: Backed out terminals Improper mating Broken locks Improperly formed or damaged terminals Poor terminal-to-wiring connections Physical damage to the wiring harness
3. The following conditions may cause an intermittent malfunction: A poor connection Rubbed-through wire insulation A broken wire inside the insulation
4. If an intermittent malfunction exists, refer to «Inducing Intermittent Fault Conditions»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) for further diagnosis.

Traction Off Indicator Always On

The TRAC OFF indicator is controlled by the instrument cluster via class 2 serial data messages from the electronic brake control module (EBCM). When the body control module (BCM) sees the traction control switch input grounded through the momentary traction control switch, it sends a class 2 message to the EBCM that tells the EBCM that the traction control switch has been pressed. The EBCM then disables traction control and sends a message to the instrument cluster to turn the TRAC OFF indicator ON. Each time the ignition is cycled from OFF to ON, the traction control system is enabled.

The following conditions will cause the TRAC OFF indicator to illuminate

1. The EBCM has disabled the traction control system (TCS) due to a DTC.
2. The driver manually disabling the TCS via the traction control switch
3. The instrument cluster bulb check-When the ignition switch is turned to ON, the TRAC OFF indicator will turn ON for approximately 3 seconds and then turn OFF.

1. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
2. Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: Backed out terminals Improper mating Broken locks Improperly formed or damaged terminals Poor terminal-to-wiring connections Physical damage to the wiring harness
3. The following conditions may cause an intermittent malfunction: A poor connection Rubbed-through wire insulation A broken wire inside the insulation
4. If an intermittent malfunction exists, refer to «Inducing Intermittent Fault Conditions»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) for further diagnosis.

Traction Off Indicator Inoperative

Bleeding the ABS System

Note. Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Cautions and Notices.

Perform a manual or pressure bleeding procedure. Refer to Hydraulic Brake System Bleeding (Manual) or Hydraulic Brake System Bleeding (Pressure) in Hydraulic Brakes. If the desired brake pedal height results are not achieved, perform the automated bleed procedure below.

The procedure cycles the system valves and runs the pump in order to purge the air from the secondary circuits normally closed off during normal base brake operation and bleeding. The automated bleed procedure is recommended when air ingestion is suspected in the secondary circuits or when the BPMV has been replaced.

Automated Bleed Procedure

1. Raise the vehicle on a suitable support. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/i-2004-2009/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove all four tire and wheel assemblies. Refer to «Tire and Wheel Removal and Installation»(/buick/lacrosse/i-2004-2009/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
3. Inspect the brake system for leaks and visual damage. Refer to «Brake Fluid Loss»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss) or «Symptoms - Hydraulic Brakes»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system__symptoms-hydraulic-brakes) in Hydraulic Brakes. Repair or replace as needed.
4. Inspect the battery state of charge. Refer to «Battery Inspection/Test»(/buick/lacrosse/i-2004-2009/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
5. Install a scan tool.
6. Turn ON the ignition, with the engine OFF.
7. With the scan tool, establish communications with the EBCM. Select Special Functions. Select Automated Bleed from the Special Functions menu.
8. Bleed the base brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) or «Hydraulic Brake System Bleeding (Pressure)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) in Hydraulic Brakes.
9. Follow the scan tool directions until the desired brake pedal height is achieved.
10. If the bleed procedure is aborted, a malfunction exists. Perform the following steps before resuming the bleed procedure: If a DTC is detected, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) and diagnose the appropriate DTC. If the brake pedal feels spongy, perform the conventional brake bleed procedure again. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) or «Hydraulic Brake System Bleeding (Pressure)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) in Hydraulic Brakes.
11. When the desired pedal height is achieved, press the brake pedal in order to inspect for firmness.
12. Remove the scan tool.
13. Install the tire and wheel assemblies. Refer to «Tire and Wheel Removal and Installation»(/buick/lacrosse/i-2004-2009/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
14. Inspect the brake fluid level. Refer to «Master Cylinder Reservoir Filling»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) in Hydraulic Brakes.
15. Road test the vehicle while inspecting that the pedal remains high and firm.

Steering Angle Sensor Centering Procedure

The steering angle sensor does not require centering often. Centering of the steering angle sensor might be required after certain service procedures are performed. Some of these procedures are as follows

1. Steering gear replacement
2. Steering column replacement
3. Steering angle sensor replacement
4. Intermediate shaft replacement
5. Antilock brake system (ABS) controller replacement
6. Collision or other physical damage
7. Engine cradle replacement

The steering angle sensor centering procedure can be preformed with a scan tool in the automated center procedure by the following

1. Using the steering wheel, align the front wheels forward.
2. Set the transmission in the park position.
3. Install the scan tool to the data link connector (DLC).
4. Turn the ignition switch ON, with the engine OFF.
5. Select ABS/traction control system (TCS)/vehicle stability enhancement system (VSES), special function out put test and automated centering procedure.
6. Follow the scan tool directions to complete the automated centering procedure.
7. Clear any DTCs that may be set. Perform the Diagnostic System Check to verify no current DTCs. Refer to «Diagnostic System Check - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) .
8. Centering of the steering angle sensor is complete.

Removal Procedure

Note. Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Cautions and Notices.

Note. To prevent equipment damage, never connect or disconnect the wiring harness connection from the EBCM with the ignition switch in the ON position.

1. Turn the ignition switch to the OFF position.
2. Remove the fuel injector sight shield, 3.8L engine only. Refer to «Fuel Injector Sight Shield Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
3. Remove the front fender upper diagonal brace. Refer to «Brace Replacement - Front Fender Upper Diagonal»(/buick/lacrosse/i-2004-2009/remont/exterior-body-panels/#body-front-end) in Body Front End.
4. Remove the air cleaner intake duct. Refer to «Air Cleaner Intake Duct Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L or «Air Cleaner Intake Duct Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction-2-of-2) in Engine Controls - 3.6L (LY7).
5. Disengage the locking tab (1) from the electronic brake control module (EBCM) harness connector.
6. Disconnect the EBCM harness connector.
7. Remove any dirt/debris from the assembly.
8. Remove the 6 EBCM to brake pressure modulator valve (BPMV) retaining bolt/screws.
9. Separate the EBCM (1) from the BPMV (4) by gently pulling apart until separated.
10. Disconnect the pump motor connector (3) at the bottom of the EBCM.

Installation Procedure

1. Connect the pump motor connector (3) to the bottom of the EBCM.
2. Install the EBCM (1) to the BPMV (4).
3. Install the 6 EBCM to BPMV retaining bolt/screws (2). Tighten: Tighten the retaining bolt/screws to 2.9 N.m (26 lb in).
4. Connect the EBCM harness connector.
5. Reengage the locking tab (1) to the EBCM harness connector.
6. Install the air cleaner intake duct. Refer to «Air Cleaner Intake Duct Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-38l-introduction-2-of-2) in Engine Controls - 3.8L or «Air Cleaner Intake Duct Replacement»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction-2-of-2) in Engine Controls - 3.6L (LY7).
7. Install the front fender upper diagonal brace. Refer to «Brace Replacement - Front Fender Upper Diagonal»(/buick/lacrosse/i-2004-2009/remont/exterior-body-panels/#body-front-end) in Body Front End.
8. Install the fuel injector sight shield, 3.8L engine only. Refer to «Fuel Injector Sight Shield Replacement»(/buick/lacrosse/i-2004-2009/remont/mechanical/#engine-mechanical-38l) in Engine Mechanical - 3.8L.
9. Turn the ignition switch to the RUN position, do not start engine.
10. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information.

Note. Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Cautions and Notices.

1. Turn the ignition switch to the OFF position.
2. Pull out lock tab (1) from electronic brake control module (EBCM) harness connector.
3. Disconnect the EBCM harness connector.
4. Disconnect the wheel cylinder brake pipes (1) from the BPMV (2).
5. Disconnect the master cylinder brake pipes (1) from the BPMV (2).
6. Remove the 2 nuts (1) that connect the BPMV to the BPMV bracket.
7. Remove the BPMV (2) and EBCM as an assembly from the vehicle.
8. Remove EBCM if replacing the BPMV only. Refer to «Electronic Brake Control Module Replacement»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system) .

1. Install EBCM if replacing the BPMV only. Refer to «Electronic Brake Control Module Replacement»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system) .
2. Install BPMV (2) and EBCM as an assembly into the BPMV bracket. Align the flats of the studs on the BPMV with the BPMV bracket.
3. Install the 2 BPMV to BPMV bracket nuts (1). Tighten: Tighten the 2 BPMV to BPMV bracket nuts to 12 N.m (8 lb ft).
4. Install the master cylinder brake pipes (1) on the BPMV (2).
5. Install the wheel cylinder brake pipes (1) on the BPMV (2). Tighten: Tighten all of the brake pipe fittings to 15 N.m (11 lb ft).
6. Connect the EBCM harness connector. Push in lock tab (1).
7. Fill and bleed the brake hydraulic system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) or «Hydraulic Brake System Bleeding (Pressure)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) in Hydraulic Brakes.
8. Turn the ignition switch to the RUN position, engine off.
9. Perform the «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) .

1. Thoroughly clean all contaminants from around the EBCM.
2. Disconnect the brake fluid pressure sensor electrical connector (3) from the brake fluid pressure sensor (2).
3. Remove the brake fluid pressure sensor (2) from the EBCM (1).

1. Install the brake fluid pressure sensor (2) to the EBCM (1). Tighten: Tighten the brake fluid pressure sensor to 20 N.m (15 lb ft).
2. Connect the brake fluid pressure sensor electrical connector (3) to the brake fluid pressure sensor (2).
3. Fill and bleed the hydraulic brake system. Refer to «Master Cylinder Reservoir Filling»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) and «Hydraulic Brake System Bleeding (Manual)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) or «Hydraulic Brake System Bleeding (Pressure)»(/buick/lacrosse/i-2004-2009/remont/mechanical-hydraulic/#hydraulic-brake-system) in Hydraulic Brakes.
4. Perform the Auto Bleed Procedure. Refer to «ABS Automated Bleed Procedure»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system) .
5. Perform the ABS Diagnostic System Check. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) .

Note. Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Cautions and Notices.

1. Turn the Ignition switch to the OFF position.
2. Remove brake pressure modulator valve (BPMV) and electronic brake control module (EBCM) as an assembly from the BPMV bracket. Refer to «Brake Pressure Modulator Valve (BPMV) Replacement»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system) .
3. Remove the 3 BPMV bracket nuts (1, 2, 3) attaching the BPMV bracket (4) to the wheel housing.
4. Remove the BPMV bracket (4) from the vehicle.

1. Install the BPMV bracket (4) to the wheel house.
2. Install the 3 BPMV bracket nuts (1, 2, 3) to the studs on the BPMV bracket (4). Tighten: Tighten the 3 BPMV bracket nuts to 10 N.m (7 lb ft).
3. Install the BPMV and EBCM as an assembly to the BPMV bracket. Refer to «Brake Pressure Modulator Valve (BPMV) Replacement»(/buick/lacrosse/i-2004-2009/remont/anti-locktraction-control/#antilock-brake-system-with-traction-control-system-stability-control-system) .
4. Turn the ignition switch to the RUN position.
5. Perform the «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information__diagnostic-trouble-code-dtc-list) .

Remove the hub and bearing assembly. Refer to Wheel Bearing/Hub Replacement - Front in Front Suspension.

1. Install the hub and bearing assembly to the vehicle. Refer to «Wheel Bearing/Hub Replacement - Front»(/buick/lacrosse/i-2004-2009/remont/suspension-front/#front-suspension-system) in Front Suspension.
2. Turn the ignition switch to the ON position with the engine off.
3. Perform the diagnostic system check. Refer to «Diagnostic System Check - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information.

Remove the hub and bearing assembly. Refer to Wheel Bearing/Hub Replacement - Rear in Rear Suspension.

1. Install the hub and bearing assembly to the vehicle. Refer to «Wheel Bearing/Hub Replacement - Rear»(/buick/lacrosse/i-2004-2009/remont/suspension-rear/#rear-suspension-system) in Rear Suspension.
2. Turn the ignition switch to the ON position, with the engine off.
3. Perform the diagnostic system check. Refer to «Diagnostic System Check - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information.

Scheme 10

Traction Control Switch Replacement

1. Turn OFF the ignition.
2. Remove the front floor center console. Refer to «Console Replacement - Front Floor»(/buick/lacrosse/i-2004-2009/remont/gauges-instrument-panels/#instrument-panel-gages-and-console) in Instrument Panel, Gages and Console.
3. Remove the 2 yaw rate sensor/lateral accelerometer mounting nuts (2).
4. Disconnect the yaw rate sensor/lateral accelerometer electrical connector (2) from the yaw rate sensor/lateral accelerometer.
5. Remove the yaw rate sensor/lateral accelerometer (1).

1. Install the yaw rate sensor/lateral accelerometer (1).
2. Install the 2 yaw rate sensor/lateral accelerometer nuts (2). Tighten: Tighten the yaw rate sensor/lateral accelerometer mounting nuts to 25 N.m (18 lb ft).
3. Connect the yaw rate sensor/lateral accelerometer electrical connector (2) to the yaw rate sensor/lateral accelerometer (1).
4. Install the front floor center console. Refer to «Console Replacement - Front Floor»(/buick/lacrosse/i-2004-2009/remont/gauges-instrument-panels/#instrument-panel-gages-and-console) in Instrument Panel, Gages and Console.
5. Perform the ABS Diagnostic System Check. Refer to «Diagnostic System Check - Vehicle»(/buick/lacrosse/i-2004-2009/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information.

Scheme 11

Scheme 12

This vehicle is equipped with the BOSCH 5.3 antilock braking system.

The vehicle is equipped with the following braking systems

1. Antilock Brake System (ABS)
2. Dynamic Rear Proportioning (DRP)
3. Traction Control System (ETS) (w/NW7)
4. Traction Control System (TCS) (w/NW9)
5. Vehicle stability enhancement system (VSES)

The following components are involved in the operation of the above systems

1. Electronic brake control module (EBCM)-The EBCM controls the system functions and detects failures. The EBCM contains the following components: System relay-The system relay is energized when the ignition is ON and no ABS DTCs are present. It supplies battery positive voltage to the solenoid valves and pump motor. Vent tube-The vent tube, located in the EBCM, is an opening to the internal cavity of the EBCM. It allows ventilation of the EBCM internals.
2. Brake pressure modulator valve (BPMV)-The BPMV contains the hydraulic valves and pump motor that are controlled electrically by the EBCM. The BPMV uses a 4-circuit configuration with a diagonal split. The BPMV directs fluid from the reservoir of the master cylinder to the left front and right rear wheels and fluid from the other reservoir to the right front and left rear wheels. The diagonal circuits are hydraulically isolated so that a leak or malfunction in one circuit will allow continued braking ability on the other. IMPORTANT: There is a rubber isolator located under the BPMV and on the mounting studs. The rubber isolators protect the BPMV and the EBCM from vehicle vibrations. The BPMV contains the following components: Pump motor Inlet valves, one per wheel Outlet valves, one per wheel Master cylinder isolation valves (w/NW9), one per drive wheel Prime valves (w/NW9), one per drive wheel
3. Wheel speed sensors (WSS)-As the wheel spins, the wheel speed sensor produces an AC signal. The EBCM uses this AC signal to calculate wheel speed. The wheel speed sensors are replaceable only as part of the wheel hub and bearing assemblies.
4. Traction control switch (w/NW9)-The TCS is manually disabled or enabled using the traction control switch.
5. Brake pedal position sensor (BPPS)-The body control module (BCM) uses the BPPS as an indication that the brake pedal is applied and sends a brake apply class 2 signal to the EBCM.
6. Lateral accelerometer sensor (w/JL4)-The EBCM uses the lateral accelerometer sensor as an indication of the lateral acceleration of the vehicle.
7. Yaw rate sensor (w/JL4)-The EBCM uses the yaw rate sensor as an indication of the yaw rate of the vehicle.
8. Steering wheel position sensor (SWPS) (w/JL4)-The EBCM uses the SWPS as an indication of the position and rotation of the steering wheel.
9. Brake pressure sensor (w/JL4)-The EBCM uses the brake pressure sensor for more accurate control during a VSES event.

Initialization Sequence

The electronic brake control module (EBCM) performs one initialization test each ignition cycle. The initialization of the EBCM occurs when one set of the following conditions occur

Both of the following conditions occur

1. The EBCM receives that there is a minimum of 500 RPM from the powertrain control module (PCM) via class 2 serial data message.
2. The brake pedal is not applied.

OR

Both of the following conditions occur

1. The vehicle speed is greater than 16 km/h (10 mph).
2. The brake pedal is applied.

The initialization sequence may also be commanded with a scan tool.

The initialization sequence cycles each solenoid valve and the pump motor, as well as the necessary relays for approximately 1.5 seconds to check component operation. The EBCM sets a DTC if any error is detected. The initialization sequence may be heard and felt while it is taking place and is considered part of normal system operation.

The EBCM defines a drive cycle as the completion of the initialization sequence.

When wheel slip is detected during a brake application, the ABS enters antilock mode. During antilock braking, hydraulic pressure in the individual wheel circuits is controlled to prevent any wheel from slipping. A separate hydraulic line and specific solenoid valves are provided for each wheel. The ABS can decrease, hold or increase hydraulic pressure to each wheel brake. The ABS cannot, however, increase hydraulic pressure above the amount which is transmitted by the master cylinder during braking.

During antilock braking, a series of rapid pulsations is felt in the brake pedal. These pulsations are caused by the rapid changes in position of the individual solenoid valves as the electronic brake control module (EBCM) responds to wheel speed sensor inputs and attempts to prevent wheel slip. These pedal pulsations are present only during antilock braking and stop when normal braking is resumed or when the vehicle comes to a stop. A ticking or popping noise may also be heard as the solenoid valves cycle rapidly. During antilock braking on dry pavement, intermittent chirping noises may be heard as the tires approach slipping. These noises and pedal pulsations are considered normal during antilock operation.

Vehicles equipped with ABS may be stopped by applying normal force to the brake pedal. Brake pedal operation during normal braking is no different than that of previous non-ABS systems. Maintaining a constant force on the brake pedal provides the shortest stopping distance while maintaining vehicle stability.

Pressure Hold

The electronic brake control module (EBCM) closes the inlet valve and keeps the outlet valve closed in order to isolate the system when wheel slip occurs. This holds the pressure steady on the brake so that the hydraulic pressure does not increase or decrease.

Pressure Decrease

The electronic brake control module (EBCM) decreases the pressure to individual wheels during a deceleration when wheel slip occurs. The inlet valve is closed and the outlet valve is opened. The excess fluid is stored in the accumulator until the return pump can return the fluid to the master cylinder.

Pressure Increase

The electronic brake control module (EBCM) increases the pressure to individual wheels during a deceleration in order to reduce the speed of the wheel. The inlet valve is opened and the outlet valve is closed. The increased pressure is delivered from the master cylinder.

Dynamic Rear Proportioning (DRP)

The dynamic rear proportioning (DRP) is a control system that replaces the hydraulic proportioning function of the combination valves in the base brake system. The DRP control system is part of the operation software in the electronic brake control module (EBCM). The DRP uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.

Traction Control System (TCS) (NW7)

The traction control system (TCS) compares front wheel speeds to rear wheel speeds to determine if drive wheels lose traction. The TCS activates when drive wheel speed exceeds speed of non-drive wheels by a calibrated value. This allows the driver to maintain acceleration and directional stability while accelerating on low tractions surfaces.

The TCS limits wheel slip during acceleration when one or more of the drive wheels lose traction. The brake switch must be off for TCS to operate.

During a traction event, the electronic brake control module (EBCM) sends a requested torque value to the powertrain control module (PCM) over the serial data link. The PCM initiates an engine torque reduction routine to slow down the drive wheels. This routine consists of ignition spark timing reduction, fuel injector cut-off and transmission shift control. The PCM also sends a torque delivered value to the EBCM over the serial data link.

If the EBCM detects a malfunction, it will disable TCS and will command the body control module (BCM) to turn the TCS OFF indicator ON. The driver can also disable TCS, if desired by pressing the TCS switch.

Traction Control System (TCS) (NW9)

The traction control system (TCS) is designed to limit wheel slip during acceleration when one or more of the drive wheels are accelerating too rapidly. Traction control will not have any effect on vehicle operation until the electronic brake control module (EBCM) detects one or both of the front wheels rotating faster than the rear wheels. The TCS accomplishes this by 2 methods, engine torque reduction and brake intervention. The 2 methods are used together to control wheel slip during acceleration. Both methods are described below.

Vehicle Stability Enhancement System (VSES)

The vehicle stability enhancement system (VSES) is also known as the Stabilitrak Plus system and the instrument cluster indicator lamp is labeled Stability Off. The VSES consists of a yaw/lateral accelerometer sensor, a steering angle sensor and a brake pressure sensor working in conjunction with the electronic brake control module (EBCM).

The yaw rate sensor and lateral accelerometer sensor are both in the same module and use a reference voltage of 5 volts. The lateral accelerometer sensor's operating range is 1.5 g resulting in an output range of 2.5-4.75 volts. The yaw rate sensor's range is 75 degrees/seconds, resulting in a signal proportional output of 0.25-4.75 volts. Zero yaw rate is 2.5 volts. The yaw/lateral accelerometer sensor is located inside the center console, between the automatic transaxle gear selector and the console storage compartment.

The steering angle sensor sends dual controller area network (CAN) signals to the EBCM. The EBCM determines steering wheel position and rotation using these signals. The steering angle sensor is located in the lower left hand side of the I/P, on the bottom of the steering column.

The brake pressure sensor uses a reference voltage of 5 volts. The sensor's operating range is 0.25-4.75 volts. The EBCM uses input from the brake pressure sensor for more accurate control during a VSES event.

Magnasteer

The variable effort steering system, Magnasteer, incorporates a controller into the electronic brake control module (EBCM). The EBCM receives inputs from wheel speed sensors. The EBCM processes this information and controls the amount of current to the Magnasteer actuator to vary the rate of input torque required at the steering gear. A DTC is stored in the EBCM for a Magnasteer malfunction. A Magnasteer DTC C0450 will not cause the ABS or TRAC OFF indicators to go ON. Refer to Variable Effort Steering System Description and Operation .

ABS Indicator

The instrument panel cluster (IPC) illuminates the ABS indicator when the following occurs

1. The electronic brake control module (EBCM) detects a malfunction with the antilock brake system. The IPC receives a class 2 message from the EBCM requesting illumination.
2. The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
3. The IPC detects a loss of class 2 communications with the EBCM.

Service ABS System

The message center displays the service ABS system message when any one of many ABS-disabling DTCs is set. The electronic brake control module (EBCM) sends a serial data message to the driver information center (DIC) requesting this display.

Stability Off Indicator

The instrument panel cluster (IPC) illuminates the Stability Off indicator when the electronic brake control module (EBCM) detects a malfunction in the vehicle stability enhancement system (VSES). The IPC receives a class 2 message from the EBCM requesting illumination of both the VSES indicator and the TRAC OFF indicator. The EBCM disables both the vehicle dynamic system and the traction control system.

Brake Warning Indicator

The instrument panel cluster (IPC) illuminates the brake indicator when the following occurs

1. The body control module (BCM) detects that the park brake is engaged. The IPC receives a class 2 message from the BCM requesting illumination. If the vehicle is shifted out of park with the park brake engaged, the BCM activates an audible warning.
2. The IPC detects a low brake fluid condition (signal circuit is low).
3. The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

Service Traction System Message

The driver information center (DIC) displays the service traction system message when any one of many ABS-disabling DTCs is set. The electronic brake control module (EBCM) sends a serial data message to the DIC requesting this display.

Traction Control Active Message

The DIC the traction active message when engine torque reduction or brake pressure application is required to maintain traction. The EBCM sends a serial data message to the DIC requesting this display.

Traction Control Off Message

The DIC traction control off indicator when the following occurs

1. The EBCM disables engine torque reduction due to a malfunction and sends a serial data message to the DIC requesting illumination.
2. The driver manually disables the traction control system (TCS) and engine torque reduction by pressing the traction control switch. The EBCM sends a serial data message to the instrument panel cluster (IPC) requesting illumination.

Stability Control Active Message

The message center displays the stability system active message when a traction control system (TCS) or vehicle stability enhancement system (VSES) event occurs. The electronic brake control module (EBCM) sends a serial data message to the instrument panel cluster (IPC) requesting this display.

Stability Control Off Message

The message center displays the service stability system message when any one of many VSES-disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.

Service Stability System Message

The message center displays the service stability system message when any one of many VSES-disabling DTCs is set. The EBCM sends a serial data message to the IPC requesting this display.

Special Tools

Special Tools Illustration Tool Number/Description J 39700 Breakout Box J 39700-25 Breakout Box Adapter J 39700-530 Cable Adapter

Scheme 13

Scheme 14

See also:
• Diagnostic System Check - Vehicle
• Lifting and Jacking the Vehicle
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Wiring Repairs
• Wheel Bearing/Hub Replacement - Front
• Wheel Bearing/Hub Replacement - Rear
• Control Module References
• Circuit Testing
• Diagnostic Trouble Code (DTC) List - Vehicle
• Brake Pedal Position Sensor Calibration
• Computer/Integrating Systems Connector End Views
• Stop Lamps Always On
• Brake Pedal Position Sensor Replacement
• Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement
• Powertrain Control Module (PCM) Replacement
• Checking Aftermarket Accessories
• Testing for Short to Ground
• Instrument Panel Cluster (IPC) Replacement
• Testing for Continuity
• Brake Fluid Irritant Caution
• Brake Fluid Effects on Paint and Electrical Components Notice
• Hydraulic Brake System Bleeding (Manual)
• Tire and Wheel Removal and Installation
• Brake Fluid Loss
• Symptoms - Hydraulic Brakes
• Battery Inspection/Test
• Master Cylinder Reservoir Filling
• Fuel Injector Sight Shield Replacement
• Brace Replacement - Front Fender Upper Diagonal
• Air Cleaner Intake Duct Replacement
• Air Cleaner Intake Duct Replacement
• Fastener Notice
• Fastener Tightening Specifications
• Variable Effort Steering System Description and Operation
• DTC C0035-C0051
• ABS Connector End Views
• Special Tools
• Diagnostic Test Drive
• Steering Angle Sensor Centering Procedure
• Scan Tool Data List