Anti-Lock Brake System — Buick LeSabre VIII (2000-2005)

FASTENER TIGHTENING SPECIFICATIONS

Application	Specification
Application	Metric	English
BPMV Brake Pipes	15 N.m	11 lb ft
BPMV to Frame Mounting Bolts	9 N.m	80 lb in
BPMV to Bracket Mounting Nuts	10 N.m	89 lb in
Brake Pressure Modulator Valve (BPMV) Bracket Mounting Bolts	12 N.m	106 lb in
Electronic Brake Control Module (EBCM) to BPMV Mounting Screws	3.2 N.m	28 lb in
Lateral Accelerometer Mounting Screws	2.4 N.m	21 lb in
Traction Control Mounting Screw	2 N.m	18 lb in
Yaw Rate Sensor Mounting Nuts	6 N.m	53 lb in

Fastener Tightening Specifications

Scheme 1

Scheme 1: ABS SCHEMATIC ICONS

Scheme 2

Scheme 2: ABS SCHEMATICS

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Scheme 7

Scheme 7: ABS COMPONENT VIEWS

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Scheme 14

Scheme 14: ABS CONNECTOR END VIEWS

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Begin the system diagnosis with DIAGNOSTIC SYSTEM CHECK - ABS . The Diagnostic System Check will provide the following information

The identification of the control modules which command the system.
The ability of the control modules to communicate through the serial data circuit.
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.

Circuit Description

The ABS Diagnostic System Check is an organized approach to identify problems associated with the EBCM. This check must be the starting point for any EBCM complaint, and will direct you to the next logical step in diagnosing the complaint. The EBCM is a very reliable component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring, connectors, and occasionally to components. Understanding the ABS system and using the tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.

Test Description

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

2 Lack of communication may be due to a partial malfunction of the serial data circuit or due to a total malfunction of the serial data circuit. The specified procedure will determine the particular condition.
4 The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Scheme 24

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DIAGNOSTIC SYSTEM CHECK - TIRE PRESSURE MONITORING

Install a scan tool. Does the scan tool power up? If so, proceed to next step. If not, go to «SCAN TOOL DOES NOT POWER UP»(/buick/lesabre/viii-2000-2005/remont/communication-devices/#data-link-communication-system) in Data Link Communications.
Turn ON the ignition, with the engine OFF. Attempt to establish communications with the Electronic Brake Control Module (EBCM). Does the scan tool communicate with the EBCM? If so, proceed to next step. If not, go to «SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE»(/buick/lesabre/viii-2000-2005/remont/communication-devices/#data-link-communication-system) in Data Link Communications.
With the scan tool, Select the ABS Diagnostic Trouble Code (DTCs) function on the scan tool. Does the scan tool display any ABS DTCs? If so, go to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) . If not, proceed to next step.
Does the scan tool display DTC C1245? If so, go to «DTC C1245»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) . If not, system is okay.

Scheme 26

Scheme 26: SCAN TOOL OUTPUT CONTROLS

Scheme 27

Scheme 27: SCAN TOOL DATA LIST

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SCAN TOOL DATA DEFINITIONS

8-Digit GM Part Number The scan tool displays the part number of the control module.
ABS Active The scan tool displays Yes or No. The active status of the ABS. Indicates if ABS is currently active.
ABS Active Indicator The scan tool displays Off or On. Indicates if the EBCM is commanding the ABS active indicator ON.
ABS Failed The scan tool displays Yes or No. The failed status of the ABS. Indicates if the EBCM disabled ABS due to a malfunction.
ABS Failed Lamp Command The scan tool displays Off or On. Indicates if the EBCM is commanding the ABS indicator ON.
ABS Reference Speed The scan tool displays 0 to 255 km/h (0 to 159 mph). The vehicle speed from the average of all four wheel speeds.
ABS Warning Indicator The scan tool displays Off or On. Indicates if the EBCM is commanding the ABS indicator.
Battery Voltage The scan tool displays 0-30 Volts. The voltage measured between the module's battery positive voltage circuit and ground circuit.
Brake Temp Status The scan tool displays Normal or Over Temp. The status of the brake temperature. Indicates if the brake temperature is above the traction control thermal cutoff point. If brake temperatures are above the thermal cutoff point, Over Temp is displayed and traction control is temporarily suspended until the brake temperature cools below the cutoff. This feature is used to maintain braking effectiveness if the base braking system is required. Overly heated brakes could result in brake fade.
Calibration ID The scan tool displays the 4-digit calibration ID of the control module.
DE Base Part Number The scan tool displays the base part number of the EBCM.
DE Build Sequence Number The scan tool displays the number in order that the EBCM was built.
DE Calibration Part Number The scan tool displays the calibration part number of the EBCM.
DE End Model Part Number The scan tool displays the end model part number of the EBCM.
DE ROM Part Number The scan tool displays the ROM part number of the EBCM.
Delivered Torque PWM Duty Cycle The scan tool displays 0 to 100%. The duty cycle of the delivered torque signal. The duty cycle of the signal is used to transmit how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The signal is at low values (approximately 10 percent) at idle and at higher values under driving conditions.
DRP Active The scan tool displays Yes or No. The active status of the DRP. Indicates if DRP is currently active.
DRP Disabled The scan tool displays Yes or No. The failed status of the DRP. Indicates if the EBCM disabled DRP due to a malfunction.
Dual Analog SWPS Input A The scan tool displays 0 to 5 volts. The steering wheel position signal A input.
Dual Analog SWPS Input B The scan tool displays 0 to 5 volts. The steering wheel position signal B input.
Engine RPM The scan tool displays 0 to 9999 RPM. The crankshaft rotation speed.
Engine Type The scan tool displays the type of the engine in the vehicle.
Estimated Trans. Gear The scan tool displays Park, Reverse, Neutral, First, Second, Third, or Fourth. The estimated state of the transmission gear.
Extended Travel Brake Switch The scan tool displays Applied or Released. The state of the extended travel brake switch.
Ignition Voltage The scan tool displays 0 to 17 volts. The level of ignition voltage at the EBCM.
Intake Air Temperature The scan tool displays -40 to +151°C (-40 to +304°F). The temperature of the intake manifold air.
Julian Date Code The scan tool displays year and day. The first digit indicates the last digit of the year that the EBCM was built. The remaining 3-digits indicate the day of the year that the EBCM was built.
Lateral Acceleration The scan tool displays -1.2 to +1.2 g. The lateral acceleration from the lateral accelerometer signal.
Lateral Accelerometer Input The scan tool displays 0 to 5 volts. The lateral accelerometer signal from the lateral accelerometer sensor, roughly 2.5 volts equals 0 g lateral acceleration.
Lateral Accelerometer - Engineering Units The scan tool displays -1.2 to +1.2 g. The lateral acceleration of the lateral accelerometer signal.
LF Rotor Temperature The scan tool displays -40 to +650°C (-40 to +1202°F). The estimated temperature of the left front brake rotor.
LF Wheel Speed The scan tool displays 0 to 255 km/h (0 to 159 mph). The actual speed of the left front wheel.
Low Tire Pressure The scan tool displays Yes or No. Indicates if the EBCM has determined that a tire has low pressure.
Low Tire Pressure Reset Switch The scan tool displays Was Pressed. Indicates if the tire pressure reset switch was pressed.
LR Wheel Speed The scan tool displays 0 to 255 km/h (0 to 159 mph). The actual speed of the left rear wheel.
Manufacturing Shift Info. The scan tool displays the shift when the EBCM was built.
Manufacturing Site The scan tool displays the location where the EBCM was built.
Powertrain TCS Failure The scan tool displays Yes or No. Indicates if the PCM has suspended TCS due to a malfunction related to TCS.
PROM ID The scan tool displays the 4-digit PROM ID of the EBCM.
Pump Motor Feedback Voltage The scan tool displays 0 to 17 volts. The voltage available to the pump motor when the pump motor control relay is energized.
Pump Motor Relay Commanded State The scan tool displays Off or On. Indicates the commanded state of the pump motor control.
Pump Motor Relay Feedback State The scan tool displays Off or On. Indicate the actual state of the pump motor control.
Red Brake Warning Indicator The scan tool displays Off or On. Indicates if the red Brake warning indicator is currently ON.
Requested Torque PWM Duty Cycle The scan tool displays 0 to 100%. The duty cycle of the requested torque signal. The duty cycle of the signal is used to transmit how much 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 duty cycle when traction control is not active and at lower values (approximately 10 percent) when traction control is active.
RF Rotor Temperature The scan tool displays -40 to +650°C (-40 to +1202°F). The estimated temperature of the right front brake rotor.
RF Wheel Speed The scan tool displays 0 to 255 km/h (0 to 159 mph). The actual speed of the right front wheel.
Rough Road Parameter The scan tool displays 0 to 1 g. The EBCM calculation of the road surface, this information is sent to the PCM via serial data messages. The PCM uses this information for misfire detection.
RR Wheel Speed The scan tool displays 0 to 255 km/h (0 to 159 mph). The actual speed of the right rear wheel.
Service Stability System The scan tool displays Off or On. Indicates if the EBCM is commanding the Service Stability System message to be displayed on the DIC.
Solenoid Relay Commanded State The scan tool displays Off or On. Indicates the commanded state of the system relay.
Solenoid Relay Feedback State The scan tool displays Off or On. Indicates the actual state of the system relay.
Stability System Active The scan tool displays Off or On. The active status of the VSES. Indicates if VSES is currently active.
State of Health Present The scan tool displays Yes or No. Indicates if the EBCM is sending the proper state of health messages.
Steering Wheel Angle The scan tool displays -720 to +720 degrees. The angle that the steering wheel is turned in degrees.
Stop Lamp Switch The scan tool displays Applied or Released. The state of the brake switch.
Switched System Battery Voltage The scan tool displays 0 to 17 volts. The level of the internal EBCM switched battery voltage available to the solenoid valves and pump motor.
System Power Mode The scan tool displays Run, Crank, Accessory, Unlock, Off Awake, RAP Unlock, or RAP. The state of the ignition as reported by the Dash Integration Module (DIM).
TCC/Brake Switch Active The scan tool displays Yes or No. The state of the brake switch.
TCS Active The scan tool displays Yes or No. The active status of the TCS. Indicates if TCS is currently active.
TCS Active Indicator/Message The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Active indicator ON.
TCS Active Message Command The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Active indicator ON.
TCS Circuit Status The scan tool displays OK or Fault. The status of the delivered torque signal circuit.
TCS Circuit History The scan tool displays history status of the requested torque signal circuit.
TCS Equipped The scan tool displays Yes or No. Indicates if the vehicle is equipped with TCS.
TCS Failed The scan tool displays Yes or No. The failed status of the TCS. Indicates if the EBCM disabled TCS due to a malfunction.
TCS Failed Lamp Command The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Off indicator ON.
TCS Off Lamp Command The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Off indicator ON.
TCS On/Off Switch The scan tool displays Was Pressed. Indicates if the traction control switch was pressed.
TCS Switch Display Off or On. Indicates the status of the traction control switch.
TCS Warning Indicator/Message The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Off indicator ON.
Temporary Inhibit of TCS The scan tool displays Yes or No. Indicates if the EBCM has suspended TCS due to a malfunction or the driver using the traction control switch.
Torque Delivered Signal The scan tool displays 0 to 100%. The duty cycle of the delivered torque signal. The duty cycle of the signal is used to transmit how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The signal is at low values (approximately 10 percent) at idle and at higher values under driving conditions.
Torque Request Signal The scan tool displays 0 to 100%. The duty cycle of the requested torque signal. The duty cycle of the signal is used to transmit how much engine torque the EBCM is requesting the PCM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal is at 90 percent duty cycle when traction control is not active and at lower values (approximately 10 percent) when traction control is active.
TPS - Pedal Position The scan tool displays 0 to 100%. The throttle angle. The display should read 0% at idle and 100% at wide open throttle.
Traction Control The scan tool displays Active or Inactive. The active status of the TCS. Indicates if TCS is currently active.
Traction Control Status The scan tool displays Active or Inactive. The active status of the TCS. Indicates if TCS is currently active.
Traction Ready Message Command The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Ready message to be displayed by the DIC.
Traction Suspended Message Comm. The scan tool displays Off or On. Indicates if the EBCM is commanding the Traction Suspended message to be displayed by the DIC.
Transmission Type The scan tool displays the type of the transmission in the vehicle.
Vehicle Yaw Rate - Engineering Units The scan tool displays -75 to +75 degree/second. The yaw rate of the yaw rate signal.
VIN Packet #2 The scan tool displays the VIN packet #2.
VSES Active The scan tool displays Yes or No. The active status of the VSES. Indicates if VSES is currently active.
VSES Active Indicator/Message The scan tool displays Off or On. Indicates if the EBCM is commanding the Stability System Active message to be displayed by the DIC.
VSES Equipped The scan tool displays Yes or No. Indicates if the vehicle is equipped with VSES.
VSES Failed The scan tool displays Yes or No. The failed status of the VSES. Indicates if the EBCM disabled VSES due to a malfunction.
VSES Failed Indicator/Message The scan tool displays Yes or No. Indicates if the EBCM is commanding the Service Stability System message to be displayed by the DIC.
VSES Is Centered The scan tool displays Yes or No. Indicates if the steering wheel is centered.
Yaw Rate Sensor Input The scan tool displays 0 to 5 volts. The yaw rate signal from the yaw rate sensor, roughly 2.5 volts equals 0 degree/second yaw rate.

Scheme 35

Scheme 35: DIAGNOSTIC TROUBLE CODE (DTC) LIST

Scheme 36

DTC	Description
DTC C1211	ABS Indicator Lamp Circuit Malfunction
DTC C1214	System Relay Contact or Coil Circuit Open
DTC C1217	Pump Motor Shorted to Ground
DTC C1218	Pump Motor Circuit Shorted to Voltage or Motor Ground Open
DTC C1221	Left Front Wheel Speed Sensor Input Signal is 0
DTC C1236	Low System Supply Voltage
DTC C1237	High System Supply Voltage
DTC C1238 (W/NW9)	Brake Thermal Model Exceeded
DTC C1242	Pump Motor Circuit Open
DTC C1243	BPMV Pump Motor Stalled
DTC C1245	Brake Sensor Pressure Always High
DTC C1248	EBCM Turned the Red Brake Warning Indicator On
DTC C1254	Abnormal Shutdown Detected
DTC C1255	EBCM Internal Malfunction
DTC C1256	EBCM Internal Malfunction
DTC C1261	Left Front Inlet Valve Solenoid Malfunction
DTC C1276, P1644, OR P1689 (W/NW9)	Delivered Torque Signal Circuit Malfunction
DTC C1277 OR P1571 (W/NW9)	Requested Torque Signal Circuit Malfunction
DTC C1278	TCS Temporarily Inhibited By PCM
DTC C1282 (W/JL4)	Yaw Rate Sensor Bias Circuit Malfunction
DTC C1284 OR C1285 (W/JL4)	Lateral Accelerometer Sensor Circuit Malfunction
DTC C1287 OR C1288 (W/JL4)	Steering Sensor Circuit Malfunction
DTC C1291 OR C1293 (W/NW9)	Open Brake Lamp Switch Contacts During Deceleration
DTC C1294 (W/NW9)	Brake Lamp Switch Circuit Always Active
DTC C1295	Brake Lamp Switch Circuit Open

DIAGNOSTIC TROUBLE CODE (DTC) LIST

DIAGNOSTIC TEST DRIVE

When servicing vehicles with 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 concerns.

The following is a suggested VSES diagnostic test drive.

Read the Diagnostic Aids and the Conditions for Setting the DTC.
Turn OFF the ignition.
Reconnect any previously disconnected components.
Start the engine.
Install a scan tool.
With the scan tool, observe the VSES Is Centered parameter in the VSES data list. The scan tool will indicate Yes with the steering wheel centered. Drive the vehicle in a straight line for 45 seconds at 24 km/h (15 mph) while monitoring the scan tool.
Remove the scan tool. NOTE: Do not perform any unlawful or unsafe maneuvers.
Drive the vehicle under the following conditions for at least 10 minutes. 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 the customers concern and duplicate driving conditions.
With the engine still running, use the scan tool in order to check for DTCs. If any DTCs are set, refer to «DIAGNOSTIC TROUBLE CODE (DTC) LIST»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

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

The number of drive cycles since the DTC last occurred.
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

Did the malfunction only occur once over a large number of drive cycles, indicating an unusual condition present when it occurred?
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.

The instrument cluster controls the operation of the ABS indicator. The EBCM reports the desired status of the ABS indicator via serial data messages. The ABS indicator signal circuit is a back-up reporting circuit to the serial data messages. The EBCM supplies ground through the circuit when the ABS is operating properly. When there is a problem with ABS that should turn on the ABS indicator, the EBCM opens the ABS indicator signal circuit. If there is a problem with the ABS serial data messages, the instrument cluster uses the ABS indicator signal to determine if the ABS indicator should be illuminated. Using the serial data messages and back-up circuit, the instrument cluster decides whether to turn on the ABS indicator.

Conditions For Running DTC

The EBCM commands the indicator OFF.

Conditions For Setting DTC

The ABS indicator signal circuit voltage is greater than 4.5 volts for 2 seconds.

Action Taken When DTC Sets

The ABS remains functional.
The ABS indicator remains OFF.

Conditions For Clearing DTC

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

Diagnostic Aids

A possible cause of this DTC is a short to battery in the ABS indicator signal circuit.

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

2 Use the scan tool to verify the normal state of the ABS indicator signal circuit.
3 Ensure that the instrument cluster can operate the ABS indicator.

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Scheme 38

The system relay is energized when the ignition is ON. The system relay supplies voltage to the solenoid valves and the pump motor. This voltage is referred to as the system voltage.

The EBCM controls each solenoid valve by grounding the solenoid.

The EBCM controls the pump motor by grounding the control circuit. The pump serves 2 purposes

Transfers brake fluid from the brake calipers to the master cylinder reservoir during pressure decrease events.
Transfers brake fluid from the master cylinder reservoir to the brake calipers during pressure increase events.

The ignition voltage is greater than 10.5 volts.
The system relay is commanded ON.

The system voltage is less than 8 volts for 0.23 seconds.

If equipped, the following actions occur

The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.
The EBCM will also set DTC C1248.
The red Brake warning indicator turns ON.

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

The system relay is integral to the EBCM. The relay is not serviceable.

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

2 Determines whether the DTC is current.

Scheme 39

The system relay is energized when the ignition is ON. The system relay supplies voltage to the solenoid valves and the pump motor. This voltage is referred to as the system voltage.

The EBCM controls each solenoid valve by grounding the solenoid.

The EBCM controls the pump motor by grounding the control circuit. The pump serves 2 purposes

Transfers brake fluid from the brake calipers to the master cylinder reservoir during pressure decrease events.
Transfers brake fluid from the master cylinder reservoir to the brake calipers during pressure increase events.

The pump motor has been commanded OFF for 1 second.
The system voltage is greater than 9 volts.

One of the following conditions exists for 0.2 seconds

The voltage across the pump motor is greater than 10.2 volts.
The pump motor low side voltage is less than 2.7 volts.

If equipped, the following actions occur

The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.
The EBCM will also set DTC C1248.
The red Brake warning indicator turns ON.

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

This DTC determines if there is a short in the pump motor control circuit.
The pump motor is integral to the BPMV. The pump motor is not serviceable.

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

3 Tests the pump motor circuits of the BPMV for a short to the housing of the BPMV. The wiring from the BPMV to the EBCM should not be repaired.

Scheme 40

The system relay is energized when the ignition is ON. The system relay supplies voltage to the solenoid valves and the pump motor. This voltage is referred to as the system voltage.

The EBCM controls each solenoid valve by grounding the solenoid.

The EBCM controls the pump motor by grounding the control circuit. The pump serves 2 purposes

Transfers brake fluid from the brake calipers to the master cylinder reservoir during pressure decrease events.
Transfers brake fluid from the master cylinder reservoir to the brake calipers during pressure increase events.

The pump motor is commanded ON.
The system voltage is greater than 8 volts.

One of the following conditions exists for 0.5 seconds

With the commanded pump motor voltage less than the system voltage, the actual pump motor voltage is 3 volts less than the commanded voltage.
With the commanded pump motor voltage greater than the system voltage, the actual pump motor voltage is less than 8 volts.

If equipped, the following actions occur

The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
The DRP does not function optimally.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.

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

The pump motor is integral to the BPMV. The pump motor is not serviceable.

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

3 Tests the ability of the EBCM to control the pump motor. If the test lamp illuminates, the pump motor circuit within the EBCM is good.

Scheme 41

Scheme 42

As the wheel spins, the wheel speed sensor produces an AC signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed.

C1221 Through C1228

DTCs C1232 through C1235 are not set.
The brake pedal is not pressed.
The ABS is not active.

C1232 Through C1235

The ignition is ON.

C1221 Through C1224

All of the following conditions exists for 2.5 seconds

The suspect wheel speed equals zero.
The other wheel speeds are greater than 8 km/h (5 mph).
The other wheel speeds are within 11 km/h (7 mph) of each other.

C1225 Through C1228

The EBCM detects a rapid variation in the wheel speed. The wheel speed changes by 16 km/h (10 mph) or more in 0.01 second. The change must occur 3 times with no more than 0.2 seconds between occurrences.

One of the following conditions exists for 0.02 seconds

A short to voltage - the wheel speed sensor signal circuit and wheel speed sensor return circuit voltages are both greater than 4.25 volts.
A short to ground - the wheel speed sensor signal circuit and wheel speed sensor return circuit voltages are both less than 0.75 volts.
An open - the wheel speed sensor signal circuit voltage is greater than 4.25 volts and wheel speed sensor return circuit voltage is less than 0.75 volts.

If equipped, the following actions occur

The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
The EBCM temporarily suspends the TIM monitoring function while the DTC is set.
The DRP does not function optimally.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.

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

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

The 2 suspect wheel speeds equal zero for 60 seconds.
The other wheel speeds are greater than 16 km/h (10 mph).
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.

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

Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater solution, add 2 teaspoons (9.9 ml) of salt to 354 ml (12 oz) of water.
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 wheel speed sensor or repair the wheel speed sensor wiring.
Rinse the area thoroughly when completed.

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

3 Measure the resistance of the wheel speed sensor in order to determine if the sensor has a valid resistance value.
4 Ensures that the wheel speed sensor is generating a valid AC voltage output.

Scheme 43

Scheme 44

The EBCM monitors the voltage level available for system operation. A low voltage condition prevents the system from operating properly.

The vehicle speed is greater than 8 km/h (5 mph).
The ignition voltage is less than 10.5 volts.
The system relay is commanded ON.

One of the following conditions exists for 0.72 seconds

During initialization or when the system is inactive, the system voltage is less than 10.5 volts.
During the system operation, the system voltage is less than 9.0 volts.

If equipped, the following actions occur

The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.
The DRP does not function optimally, or with system voltage less than 8.5 volts, the EBCM disables the DRP for the duration of the ignition cycle.
When the EBCM disables the DRP, the following actions also occur: The EBCM will also set DTC C1248. The red Brake warning indicator turns ON.

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

Test the charging system. Refer to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/charging-system/#charging-system) in Generators & Regulators.
Possible causes of this DTC are the following conditions: A charging system malfunction. An excessive battery draw. A weak battery. A faulty system ground.

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

2 Use the scan tool in order to inspect the voltage to the EBCM.
3 Use the scan tool in order to inspect the voltage to the Dash Integration Module (DIM). A low voltage value in multiple modules indicates a concern in the charging system.
4 Verifies that the condition is still present.

Scheme 45

The EBCM monitors the voltage level available for system operation. If the voltage level is too high, damage may result in the system. When the EBCM detects a high voltage condition, the EBCM turns OFF the system relay which removes battery voltage from the solenoid valves and pump motor.

The vehicle speed is greater than 8 km/h (5 mph).

The system voltage is greater than 16.4 volts for 0.72 seconds.

If equipped, the following actions occur

The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.
The EBCM will also set DTC C1248.
The red Brake warning indicator turns ON.

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

A possible cause of this DTC is overcharging.

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

2 Use the scan tool in order to inspect the voltage to the EBCM.
3 Use the scan tool in order to inspect the voltage to the Dash Integration Module (DIM). A high voltage value in multiple modules indicates a concern in the charging system.
4 Verifies that the condition is still present.

Scheme 46

The EBCM monitors vehicle speed deceleration, system activation, and stoplamp switch active times in order to calculate an estimate of the brake rotor temperatures. If the EBCM calculates that the brake rotor temperatures have exceeded the thermal cutoff point, the EBCM will temporarily suspend the TCS function until the brake rotors cool. This feature is used to maintain braking effectiveness if normal base braking is required. An overly heated brake system could result in brake fade.

The EBCM continues calculating the brake rotor temperatures after the ignition is turned OFF. The EBCM remains awake until the EBCM calculates that the brake rotors cooled sufficiently. The cooling period may take up to 30 minutes.

The ABS conditions and the braking conditions are normal.

This DTC sets when the estimated brake rotor temperature of either of the drive wheels exceeds 375°C (700°F). When the estimated brake rotor temperature of either of the drive wheels exceeds 375°C (700°F) during normal braking or normal ABS operations, the DTC does not set until the next TCS activation. The brake rotor temperature can exceed 375°C (700°F) without setting the DTC if a TCS activation has not occurred. When the estimated brake rotor temperature of either of the drive wheels exceeds 375°C (700°F) during a TCS activation, the DTC sets immediately, but the EBCM does not disable TCS until the end of the TCS event.

The EBCM disables the TCS until the DTC becomes a history DTC.
The Traction Off indicator turns ON.
The ABS remains functional.

The current DTC becomes history when the estimated brake rotor temperatures of both drive wheels decreases below 275°C (530°F). The EBCM also enables TCS.
The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

With TCS temporarily disabled, the EBCM continues calculating the brake rotor temperatures after the ignition is turned OFF. Turning ON the ignition again while TCS is temporarily disabled will not re-enable TCS.
The temperature is an estimate calculated by the EBCM.
Possible causes of this DTC are the following conditions: The brake usage is excessive. The TCS usage is excessive. The stoplamp switch is misaligned or damaged.

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

4 Use the scan tool in order to verify that the Brake Thermal Model is exceeded.

Scheme 47

The system relay is energized when the ignition is ON. The system relay supplies voltage to the solenoid valves and the pump motor. This voltage is referred to as the system voltage.

The EBCM controls each solenoid valve by grounding the solenoid.

The EBCM controls the pump motor by grounding the control circuit. The pump serves 2 purposes

Transfers brake fluid from the brake calipers to the master cylinder reservoir during pressure decrease events.
Transfers brake fluid from the master cylinder reservoir to the brake calipers during pressure increase events.

C1242

The system voltage is greater than 8.0 volts.
The system relay is ON.
The pump motor is commanded OFF.

C1243

The pump motor is ON for at least 0.3 seconds.
The system relay is ON.

The voltage across the pump motor is between 1.7 - 10.2 volts for 2 seconds.

The pump motor is stalled or turning slowly.

If equipped, the following actions occur

The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
The DRP does not function optimally.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.

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

The pump motor is integral to the BPMV. The pump motor is not serviceable.

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

3 Tests the ability of the EBCM to control the pump motor. If the test lamp illuminates, the pump motor circuit within the EBCM is good.

Scheme 48

The Tire Pressure Monitor (TPM) system uses the Electronic Brake Control Module (EBCM), and the ABS wheel speed sensor inputs to monitor tire pressure. The EBCM contains software to calculate relative tire pressure differences. The EBCM monitors the ABS wheel speed sensor inputs, which will all be the same as the learned calibration if the tire pressures stay the same. If the pressure increases or decreases in one tire so too will that tire's circumference and radius, which causes that wheel speed sensor input to change. The EBCM recognizes this change in wheel speed as a tire pressure condition.

No ABS or TCS malfunctions present.
The calibration process is at least partially complete.
The vehicle speed is between 24-145 km/h (15-90 mph).

The EBCM detects a tire pressure difference in one tire of 69 kPa (10 psi) higher or lower than the other three.
Loss of, or low system battery voltage.

Actions Taken When DTC Sets

A DTC C1245 is stored in memory.
The DIC displays the CHECK TIRE PRESSURE warning message.
The TPM system is disabled.

A current DTC will clear when the TPM system has been reset.
A history DTC will clear after 100 consecutive malfunction free ignition cycle and the TPM system has been reset.
Using the scan tool.

Any of the following conditions can cause this DTC.

The tire pressures have been adjusted without resetting the TPM system.
The tires have been rotated, or replaced without resetting the TPM system.
Rough or slippery road conditions such as dirt, gravel, wet, snow, or ice.
The tires are out of balance.
A suspension out of alignment.

Did you perform the Tire Pressure Monitor Diagnostic System Check? If so, proceed to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK - TIRE PRESSURE MONITORING»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system__diagnostic-system-check-tire-pressure) .
Inspect the tire pressures and adjust to the recommended kPa/psi if needed. Did incorrect tire pressure cause the DTC to set? If so, proceed to next step. If not, go to «Diagnostic Aids»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .
Reset the TPM system. See «TIRE PRESSURE MONITOR RESET PROCEDURE»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system__tire-pressure-monitor-reset-procedure) . When complete, proceed to next step.
Use the scan tool in order to clear the TPM DTC. Operate the vehicle within the conditions for running the DTC. Does the DTC reset? If so, go to step 2 . If not, system is okay.

The Dynamic Rear Proportioning (DRP) is a control system that replaces the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The DRP control system is part of the operating software in the EBCM. The DRP uses active control with the existing ABS in order to regulate the vehicle's rear brake pressure.

One or more faults have been detected by the EBCM in the ABS/TCS systems.

One of the following conditions exists

DTC C1214, C1217, C1237, C1254, C1255, C1261 - 1268, or C1271 - 1274 sets.
DTC C1236 sets and the system voltage is less than 8.5 volts.
Two wheel speed sensor DTCs on the same axle set.

The EBCM disables the DRP for the duration of the ignition cycle.
The red Brake warning indicator turns ON.

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

Use this DTC in order to differentiate which of the following conditions is present: The EBCM turned ON the red Brake warning indicator. The instrument cluster turned ON the red Brake warning indicator due to low brake fluid in the master cylinder reservoir. The instrument cluster turned ON the red Brake warning indicator due to the application of the park brake.
Diagnose any other ABS DTCs that set along with this DTC.

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

2 Verifies whether other ABS/TCS/VSES DTCs are set.

Scheme 49

The microprocessor contains a data storage area, keep alive memory, which can save pertinent data when the ignition is turned OFF. The Keep Alive Memory (KAM) data is lost if battery power or module ground is removed from the module. The KAM area is an integral part of the microprocessor and cannot be serviced separately.

The ABS conditions and the braking conditions are normal.

The microprocessor calculates a check sum on those areas of memory that hold critical operation data. This is done at a regular interval and is called the periodic check sum. The microprocessor also calculates a check sum on these memory locations when ever new data is written to them. This is called the running check sum.

To check the Keep Alive Memory (KAM), the microprocessor compares the periodic check sum to the running check sum. If they do not match, the microprocessor sets the DTC.

If equipped, the following actions occur

The EBCM disables the DRP/ABS/TCS/VSES/TIM for the duration of the ignition cycle.
The EBCM disables the Variable Effort Steering (VES) for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.
The red Brake warning indicator turns ON.
The EBCM will also set DTC C1245 and DTC C1248.
The EBCM will not send serial data messages.
The EBCM will not send the requested torque output to the PCM.

The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
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 the following conditions

A loss of battery ground.
A disconnected battery.
A running reset. A running reset is detected when the keep alive memory check sum is not updated properly.
A sudden drop in the system voltage to less than 5 volts.
Long extended engine cranks that cause the battery voltage to drop.
Poor power or ground connections.
An internal EBCM malfunction.

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

2 Tests for an open in the ground circuits of the EBCM.
4 Verifies the proper operation of the charging system.
6 Determines whether the DTC resets.

Scheme 50

This DTC identifies a malfunction within the EBCM.

The ABS conditions and the braking conditions are normal.

An internal EBCM malfunction exists.

C1255

If equipped, the following actions occur

The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The red Brake warning indicator turns ON.
The DIC displays the Service Stability System message.
The EBCM will also set DTC C1248.
For some DTC C1255xx, the EBCM disables the Variable Effort Steering (VES) for the duration of the ignition cycle.
For some DTC C1255xx, the EBCM temporarily suspends the TIM monitoring function while the DTC is set.

C1256

The ABS remains functional.
The ABS indicator remains OFF.

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

The scan tool displays 2 additional characters after the DTC. Take note of the 2 character code and any other DTCs that are set. The 2 character code is an engineering aid used in order to determine the cause of the internal malfunction.
When the scan tool displays DTC C1255m3, the EBCM has not been programmed. Perform the setup procedure for the EBCM.

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

2 Determines whether the DTC is current.

Scheme 51

The system relay is energized when the ignition is ON. The system relay supplies voltage to the valve solenoids and the pump motor. This voltage is referred to as the system voltage. The EBCM microprocessor activates the valve solenoids by grounding the control circuit.

The system voltage is greater than 8 volts.
The ignition voltage is greater than 9 volts.

The commanded state of the driver and the actual state of the control circuit do not match for 0.03 seconds.

If equipped, the following actions occur

The EBCM disables the DRP/ABS/TCS/VSES for the duration of the ignition cycle.
The ABS indicator turns ON.
The Traction Off indicator turns ON.
The DIC displays the Service Stability System message.
The EBCM will also set DTC C1248.
The red Brake warning indicator turns ON.

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

The solenoid valve circuit is internal to the EBCM. The solenoid valve circuit is not diagnosable external to the EBCM. The DTC sets when there is a malfunction in the solenoid circuit internal to the EBCM.

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

2 Determines whether the DTC is current.

Scheme 52

The EBCM and the PCM simultaneously control the traction control. The PCM reduces the amount of torque supplied to the drive wheels by retarding spark timing and selectively turning off fuel injectors. The EBCM actively applies the brakes to the front wheels in order to reduce torque.

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 a pull up voltage of 5 volts that the EBCM switches to ground to create the signal.

The PCM sends a delivered torque message via a Pulse Width Modulated (PWM) signal to the EBCM. The duty cycle of the signal is used to determine how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The signal should be at low values (around 10 percent) at idle and higher values under driving conditions. The EBCM supplies a pull up voltage of 12 volts that the PCM switches to ground to create the signal.

When certain PCM DTCs are set, the PCM will not be able to perform the torque reduction portion of traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.

The engine is running.

C1276

One of the following conditions exists

The EBCM detects that delivered torque signal is out of the valid range.
The EBCM does not receive the delivered torque signal.

P1644 Or P1689

The PCM detects that the delivered torque signal voltage is invalid.

The EBCM disables the TCS for the duration of the ignition cycle.
The PCM will store conditions which were present when the DTC set as Fail Records data only.
The Traction Off indicator turns ON.
The ABS remains functional.

The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
The PCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles.

The following conditions can cause this concern

An open in the delivered torque circuit.
An short to ground or voltage in the delivered torque circuit.
A wiring problem, terminal corrosion, or poor connection in the delivered torque circuit.
A communication frequency problem.
A communication duty cycle problem.
The EBCM is not receiving information from the PCM.
Loose or corroded EBCM ground or PCM ground.

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

3 Use the scan tool in order to determine if the delivered torque signal has a valid duty cycle.
9 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.

Scheme 53

Scheme 54

The engine is running.

C1277

The PCM diagnoses the requested torque signal circuit and sends a serial data message to the EBCM indicating a fault is present.

P1571

One of the following conditions exists

The PCM detects that requested torque signal is out of the valid range.
The PCM does not receive the requested torque signal.

The EBCM disables the TCS for the duration of the ignition cycle.
The PCM will store conditions which were present when the DTC set as Fail Records data only.
The Traction Off indicator turns ON.
The ABS remains functional.

The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
The PCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles.

The following conditions can cause this concern

An open in the requested torque circuit.
An short to ground or voltage in the requested torque circuit.
A wiring problem, terminal corrosion, or poor connection in the requested torque circuit.
A communication frequency problem.
A communication duty cycle problem.
The PCM is not receiving information from the EBCM.
Loose or corroded EBCM ground or PCM ground.

A DTC P1571 may set along with several other PCM DTCs if the key is held in the CRANK position while the engine is running. The starter lockout function of the PCM is enabled several seconds after the engine is running and prevents the starter from engaging while the engine is running. This will cause a partial loss of power to some components and systems.

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

3 Use the scan tool in order to determine if the requested torque signal has a valid duty cycle.
4 Measure the requested torque signal in order to determine if the signal has a valid duty cycle.
5 Measure the requested torque signal in order to determine if the signal has a valid frequency.
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.

Scheme 55

Scheme 56

The ignition is ON.

The PCM diagnoses a condition preventing the engine control portion of the traction control function and sends a serial data message to the EBCM indicating that torque reduction is not allowed. The PCM will typically set a DTC and the EBCM will set this DTC.

The EBCM disables the TCS for the duration of the ignition cycle.
The Traction Off indicator turns ON.
The ABS remains functional.

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

This DTC is for information only. As an aid to the technician, this DTC indicates that there are no problems in the ABS/TCS system.

Scheme 57

Scheme 57: DTC C1278

The Vehicle Stability Enhancement System (VSES) is activated by the 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 left or right front wheel.

The VSES activations generally occur during aggressive driving, in the turns or bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the brake pedal will feel different than the ABS pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.

The usable output voltage range for the lateral accelerometer and yaw rate sensors is 0.25-4.75 volts. The scan tool will report zero lateral acceleration or yaw rate as 2.5 volts with no sensor bias present. The sensor bias compensates for sensor mounting alignment errors, electronic signal errors, temperature changes, and manufacturing differences.

The steering wheel position sensor supplies 2 analog inputs, Phase A and Phase B, to the EBCM. The 2 input signals are approximately 90 degrees out of phase. By interpreting the relationship between the 2 inputs, the EBCM can determine the position of the steering wheel and the direction of steering wheel rotation.

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. Using the yaw rate input, lateral accelerometer input, and wheel speed sensor inputs, the initial steering center position is calculated after driving greater than 10 km/h (6 mph) for more than 10 seconds in a straight line on a level surface.

C1281

The steer angle has been centered.
The VSES is active.
The direction (understeer or oversteer) of the yaw rate error has not changed.
The centered lateral acceleration value is less than 0.5 g.

C1283

The vehicle speed is greater than 40 km/h (25 mph).

C1286

The steer angle has been centered.

One of the following conditions exists

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.
The yaw rate error is greater than 10 degrees/second for 5 seconds. Under this condition, this DTC will set along with DTC C1282.
The yaw rate error is greater than 10 degrees/second with the vehicle speed less than 60 km/h (37 mph) and the acceleration pedal is pressed more than 25 percent of the pedal travel range for 1 second during the VSES activation. Under this condition, this DTC will set along with DTC C1282.
With the steer rate less than 80 degrees/second, the difference between the 2 steering sensor signals (Phase A and Phase B) is greater than 20 degrees for 1 second. Under this condition, this DTC will set along with DTC C1287.

The vehicle has driven for 10 minutes without completing steer angle centering.

The steering sensor bias moves greater than 40 degrees after steer centering was accomplished.

The EBCM disables the VSES for the duration of the ignition cycle.
The DIC displays the Service Stability System message.
The ABS/TCS remains functional.

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

During diagnosis, park the vehicle on a level surface.
Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
Find out from the driver under what conditions the DTC was set (when the DIC displayed the Service Stability System message). This information will help to duplicate the failure.
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.

2 Perform the Steering Position Sensor Test in order to verify that the Steering Wheel Position Sensor (SWPS) is operating properly.
3 Verify that the lateral accelerometer input parameter is within the valid range.
4 Verify that the yaw rate input parameter is within the valid range.

Scheme 58

The EBCM performs 6 different tests to detect a DTC condition. The numbers below correspond to the numbers in Conditions for Setting the DTC.

The yaw rate sensor bias test runs with the ignition ON.
The yaw rate sensor acceleration test runs with the ignition ON.
The yaw rate sensor circuit test runs with the vehicle stopped or with the vehicle speed greater than 45 km/h (28 mph).
The yaw rate isolation test runs with the following conditions: The brake pedal is not pressed. The ABS is not active. The vehicle speed is greater than 5 km/h (3 mph).
The above yaw rate isolation test run with the VSES active.
The false activation test runs with the VSES active.

The EBCM performs 6 different tests to detect a DTC condition. The numbers below correspond to the numbers in Conditions for Running the DTC.

The yaw rate bias is greater than 7 degrees/second.
The yaw rate input change is greater than 390 degrees/second/second.
The yaw rate input voltage is less than 0.15 volts or greater than 4.85 volts for 1 second.
The yaw rate error is greater than 10 degrees/second 30 times within a drive cycle.
The yaw rate error is greater than 10 degrees/second for 5 seconds. Under this condition, this DTC will set along with DTC C1281.
The yaw rate error is greater than 10 degrees/second with the vehicle speed less than 60 km/h (37 mph) and the acceleration pedal is pressed more than 25 percent of the pedal travel range for 1 second during the VSES activation. Under this condition, this DTC will set along with DTC C1281.

The EBCM disables the VSES for the duration of the ignition cycle.
The DIC displays the Service Stability System message.
The ABS/TCS remains functional.

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

During diagnosis, park the vehicle on a level surface.
Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
Find out from the driver under what conditions the DTC was set (when the DIC displayed the Service Stability System message). This information will help to duplicate the failure.
The Snapshot function on the scan tool can help find an intermittent DTC.

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

2 Tests for the proper operation of the circuit in the low voltage range.
4 Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
5 Tests for a short to voltage in the 5 volt reference circuit.
6 Tests the bias voltage of the yaw rate sensor.

Scheme 59

Scheme 60

The ignition is ON.

C1284

The compensated bias value of the lateral accelerometer is greater than 0.3 g.

C1285

The lateral accelerometer input voltage is less than 0.15 volts or greater than 4.85 volts for 1 second.

The EBCM disables the VSES for the duration of the ignition cycle.
The DIC displays the Service Stability System message.
The ABS/TCS remains functional.

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

During diagnosis, park the vehicle on a level surface.
Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
Find out from the driver under what conditions the DTC was set (when the DIC displayed the Service Stability System message). This information will help to duplicate the failure.
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.

3 Tests for the proper operation of the circuit in the low voltage range.
4 Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
5 Tests for a short to voltage in the 5 volt reference circuit.
6 Tests the bias voltage of the lateral accelerometer sensor.

Scheme 61

Scheme 62

The ignition is ON.

C1287

One of the following conditions exists

The steering wheel position sensor is synchronized and the steer rate (speed that the steering wheel appears to be turning) is greater than 1100 degrees/second.
The steer rate is less than 80 degrees/second and the difference in the phase angle between Phase A and Phase B is greater than 20 degrees.
The 2 steering sensor signals (Phase A and Phase B) do not agree for 1 second. Under this condition, this DTC will set along with DTC C1281.

C1288

One of the following conditions exists

Both Phase A and Phase B are greater than 4.9 volts for 1.6 seconds.
Both Phase A and Phase B are less than 0.2 volts for 1.6 seconds.
The difference in the changes in Phase A and Phase B is greater than 35.2 degrees for 9.76 milliseconds.

The EBCM disables the VSES for the duration of the ignition cycle.
The DIC displays the Service Stability System message.
The ABS/TCS remains functional.

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

During diagnosis, park the vehicle on a level surface.
Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
Find out from the driver under what conditions the DTC was set (when the DIC displayed the Service Stability System message). This information will help to duplicate the failure.
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.

2 Perform the Steering Position Sensor Test in order to verify if the Steering Wheel Position Sensor (SWPS) is operating properly.
3 Tests for the proper operation of the steering wheel position signal A circuit in the low voltage range.
4 Tests for the proper operation of the steering wheel position signal B circuit in the low voltage range.
5 Tests for the proper operation of the steering wheel position signal A circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
6 Tests for the proper operation of the steering wheel position signal B circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
7 Tests for a short to voltage in the 5 volt reference circuit.
8 Tests for a high resistance or an open in the low reference circuit.

Scheme 63

Scheme 64

Scheme 65

The stop lamp switch signal informs the EBCM when the brake pedal is pressed.

The ABS conditions and the braking conditions are normal.

C1291

The stoplamp switch remains open for 3 deceleration cycles.

C1293

A DTC C1291 was set in a previous ignition cycle.

The EBCM disables the TCS for the duration of the ignition cycle.
The Traction Off indicator turns ON.
The ABS remains functional.

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

Diagnose any wheel speed sensor DTCs before continuing with the diagnosis of the DTC.
A deceleration cycle consists of the following sequence: The vehicle speed is greater than 24 km/h (15 mph). The vehicle decelerates more than 8 km/h/second (5 mph/second) for 2 seconds. The vehicle speed decelerates to less than 16 km/h (10 mph).
Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch on within 2.54 cm (1 in) of travel.
Possible causes of this DTC are the following conditions: An open stop lamp switch. The stop lamp switch is misadjusted. An open fuse. Circuit has a wiring problem, terminal corrosion, or poor connections. Erratic wheel speeds.

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

3 Tests the circuit for a change in states.
5 Tests for proper operation of the circuit by bypassing the stoplamp switch. If the fuse in the jumper opens when you perform this test, the signal circuit of the stoplamp switch is shorted to ground.

Scheme 66

Scheme 67

The stop lamp switch signal informs the EBCM when the brake pedal is pressed.

The vehicle speed is greater than 40 km/h (25 mph).

The stop lamp switch input was active for 2 consecutive ignition cycles.

The EBCM disables the TCS for the duration of the ignition cycle.
The Traction Off indicator turns ON.
The ABS remains functional.

The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
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 the following conditions

The stop lamp switch circuit is shorted to voltage.
The stop lamp switch is misadjusted.
The stop lamp switch is stuck closed.
A brake pedal that is binding.

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

2 Test for the current state of the stoplamp switch parameter.

Scheme 68

Scheme 69

The EBCM sources 5 volts on the stop lamp switch signal circuit when the stop lamp switch is inactive. The voltage is supplied a ground path through the stop lamp bulbs.

The ignition is ON.

The stop lamp switch input voltage is between 2.1 volts and 5.3 volts for 2 seconds.

The EBCM disables the TCS for the duration of the ignition cycle.
The Traction Off indicator turns ON.
The ABS remains functional.

The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
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 the following conditions

A signal circuit of the stop lamp switch is open.
The stop lamp switch is misadjusted.
Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch ON within 2.54 cm (1 in) of travel.
All brake lamps are open.
All brake lamp grounds are open.
Circuit has a wiring problem, terminal corrosion, or poor connections.
Loose or corroded EBCM ground or PCM ground.
An internal EBCM problem.

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

3 This DTC detects an open stop lamp switch signal circuit from the stoplamp side of the splice pack to the EBCM.
4 Verifies that the stop lamps are operating properly.

Scheme 70

Note. The following steps must be completed before using the symptom tables.

Perform the «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control module(s) can communicate via the serial data link.
Review the system operation in order to familiarize yourself with the system functions. Refer to «ABS DESCRIPTION & OPERATION»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the anti-lock brake system. Refer to «CHECKING AFTERMARKET ACCESSORIES»(/buick/lesabre/viii-2000-2005/remont/accessories-control-systems/#wiring-systems-general-information__checking-aftermarket-accessories) in Wiring Systems.
Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
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 & POOR CONNECTIONS in Wiring Systems.

Symptom List

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

«ABS INDICATOR ALWAYS ON»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)
«ABS INDICATOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)
«TRACTION OFF INDICATOR ALWAYS ON (W/NW9)»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)
«TRACTION OFF INDICATOR INOPERATIVE (W/NW9)»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)
«VEHICLE STABILITY ENHANCEMENT SYSTEM INOPERATIVE (W/JL4)»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)
«VEHICLE STABILITY ENHANCEMENT SYSTEM UNWANTED ACTIVATION (W/JL4)»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)
«VEHICLE STABILITY ENHANCEMENT SYSTEM EXCESSIVE BRAKE PULSATION»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system)

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

3 Use the scan tool to check the normal state of the ABS indicator control circuit.
4 Ensures that the instrument cluster can operate the ABS indicator.

Scheme 71

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

3 Use the scan tool to check the normal state of the ABS indicator control circuit.
4 Ensures that the instrument cluster can operate the ABS indicator.

Scheme 72

The Traction Off indicator is controlled by the instrument cluster via serial data messages from the EBCM. When the heater and A/C control (w/C67) or the Instrument Panel Module (IPM) (w/CJ2) sees the traction control switch input grounded through the momentary traction control switch, it sends a serial data 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 Traction 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 Traction Off indicator to illuminate

The EBCM has disabled the TCS due to a DTC.
The driver manually disabling the TCS via the traction control switch.
The instrument cluster bulb check. When the ignition switch is turned to ON, the Traction Off indicator will turn on for approximately 3 seconds and then turn OFF.

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

2 Use the scan tool to check the normal state of the Traction Off indicator control.
3 Ensures that the instrument cluster can operate the Traction Off indicator.

Scheme 73

The following conditions will cause the Traction Off indicator to illuminate

The EBCM has disabled the TCS due to a DTC.
The driver manually disabling the TCS via the traction control switch.
The instrument cluster bulb check. When the ignition switch is turned to ON, the Traction Off indicator will turn on for approximately 3 seconds and then turn OFF.

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

2 Use the scan tool to check the normal state of the Traction Off indicator control.
3 Ensures that the instrument cluster can operate the Traction Off indicator.

Scheme 74

Scheme 75

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

3 Perform the Steering Position Sensor Test in order to verify if the Steering Wheel Position Sensor (SWPS) is operating properly.
4 Verify that the lateral accelerometer input parameter is within the valid range.
5 Verify that the yaw rate input parameter is within the valid range.

Scheme 76

The sensor bias compensates for sensor mounting alignment errors, electronic signal errors, temperature changes, and manufacturing differences.

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

9 Perform the Steering Position Sensor Test in order to verify if the Steering Wheel Position Sensor (SWPS) is operating properly.

Scheme 77

Scheme 78

Scheme 79

Scheme 79: Circuit Description

Bleeding ABS System

Perform a manual or pressure bleeding procedure. Refer to MANUAL BLEEDING or PRESSURE BLEEDING in Disc 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

CAUTION

The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given. After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.

Raise the vehicle on a suitable support.
Remove all four tire and wheel assemblies.
Inspect the brake system for leaks and visual damage. Refer to «BRAKE FLUID LOSS»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__brake-fluid-loss) or «SYMPTOMS -- HYDRAULIC BRAKE»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__symptoms-hydraulic-brake) in Disc Brakes. Repair or replace as needed.
Inspect the battery state of charge. Refer to «BATTERY TESTING & INSPECTION»(/buick/lesabre/viii-2000-2005/remont/charging-system/#charging-system__battery-testing-inspection) in Generators & Regulators.
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With the scan tool, establish communications with the EBCM. Select Special Functions. Select Automated Bleed from the Special Functions menu.
Bleed the base brake system. Refer to «MANUAL BLEEDING»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__manual-bleeding) or «PRESSURE BLEEDING»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__pressure-bleeding) in Disc Brakes.
Follow the scan tool directions until the desired brake pedal height is achieved.
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»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) and diagnose the appropriate DTC. If the brake pedal feels spongy, perform the conventional brake bleed procedure again. Refer to «MANUAL BLEEDING»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__manual-bleeding) or «PRESSURE BLEEDING»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__pressure-bleeding) in Disc Brakes.
When the desired pedal height is achieved, press the brake pedal in order to inspect for firmness.
Remove the scan tool.
Install the tire and wheel assemblies.
Inspect the brake fluid level. Refer to «MASTER CYLINDER RESERVOIR»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes) in Disc Brakes.
Road test the vehicle while inspecting that the pedal remains high and firm.

TIRE PRESSURE MONITOR RESET PROCEDURE

Note. There are 2 ways to reset the Tire Pressure Monitor (TPM) system. After resetting, the TPM system requires up to 30 minutes of straight line driving in each of the 3 speed ranges to complete the calibration process, for further information, refer to TIRE PRESSURE MONITOR DESCRIPTION & OPERATION . If the TPM system does not reset using the Driver Information Center (DIC) procedure, refer to DRIVER INFORMATION CENTER (DIC) SWITCH(ES) IN in Instrument Panel, Gages, and Console. If DTC C1245 remains current, refer to DIAGNOSTIC SYSTEM CHECK - TIRE PRESSURE MONITORING .

Using DIC

Adjust all tire pressures to the recommended kPa/psi.
Turn ON the ignition, with the engine off.
Press the GAGE INFO button until TIRE PRESSURE is displayed.
Press and hold the RESET button until TIRE PRESSURE RESET is displayed.
Release the RESET button, TIRE PRESSURE NORMAL is displayed.
Use the scan tool in order to clear the TPM DTC.

Using Scan Tool

Adjust all tire pressures to the recommended kPa/psi.
Install a scan tool.
Turn ON the ignition, with the engine off.
With the scan tool, select Special Functions.
Select Tire Pressure Reset.
Press the Reset soft key and TIRE PRESSURE NORMAL is displayed on the DIC.
Use the scan tool in order to clear the TPM DTC.

Scheme 80

Scheme 80: Removal Procedure

Turn OFF the ignition.
Raise the vehicle.
Remove the left front wheel.
Remove the left front wheelhouse extension. Refer to «FASCIA EXTENSION REPLACEMENT - FRONT»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#bumper-system) in Bumpers. NOTE: The area around the Electronic Brake Control Module (EBCM) must be free from loose dirt to prevent contamination of disassembled ABS components.
Thoroughly wash all contaminants from around the EBCM.
Rotate the EBCM connector tab up to the unlocked position.
Remove the EBCM connector position assurance (2) from the EBCM electrical connector (1). CAUTION: To prevent equipment damage, never connect or disconnect the wiring harness connection from the EBCM with the ignition switch in the ON position.
Disconnect the EBCM electrical connector (1) from the EBCM (4).
Disconnect the Brake Pressure Modulator Valve (BPMV) electrical connector (2) from the EBCM (3).
Remove the 6 EBCM to BPMV screws (2).
Clean the surface of the EBCM/BPMV assembly. NOTE: The EBCM cannot be repaired. If faulty, the unit must be replaced.
Separate the EBCM (2) from the BPMV (1).

Scheme 81

Scheme 81: Installation Procedure

Scheme 82

Clean the seal surface of the Brake Pressure Modulator (BPMV).
Install the Electronic Brake Control Module (EBCM) (2) to the BPMV (1). CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the 6 EBCM to BPMV screws (2). Tighten the 6 screws to 3.2 N.m (28 lb in).
Connect the BPMV electrical connector (2) to the EBCM (3). CAUTION: To prevent equipment damage, never connect or disconnect the wiring harness connection from the EBCM with the ignition switch in the ON position.
Connect the EBCM electrical connector (1) to the EBCM (4).
Install the EBCM connector position assurance (2) to the EBCM electrical connector (1).
Rotate the EBCM connector tab (2) down to the locked position.
Install the left front wheelhouse extension. Refer to «FASCIA EXTENSION REPLACEMENT - FRONT»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#bumper-system) in Bumpers.
Install the left front wheel.
Lower the vehicle. NOTE: An unprogrammed EBCM will result in the following conditions: Inoperative or poorly functioning DRP/ABS/TCS/VSES/TIM/VES if equipped. Set DTC C1248 EBCM Turned the Red Brake Warning Indicator On. Set DTC C1255m3 EBCM Internal Malfunction.
If a replacement EBCM is being installed, it must be programmed using the latest software matching the vehicle. Refer to the Techline Terminal/Equipment user's instructions.
Use the scan tool in order to clear the DTCs.
Perform the ABS Diagnostic System Check. Refer to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Removal Procedure

WARNING

For safety reasons, the brake pressure modulator valve assembly must not be repaired, the complete unit must be replaced. With the exception of the EBCM, no screws on the brake pressure modulator valve assembly may be loosened. If screws are loosened, It will not be possible to get the brake circuits leak-tight and personal injury may result.

Scheme 83

Scheme 84

Turn OFF the ignition.
Raise the vehicle.
Remove the left front wheel.
Remove the left front wheelhouse extension. Refer to «FASCIA EXTENSION REPLACEMENT - FRONT»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#bumper-system) in Bumpers. NOTE: The area around the electronic brake control module (EBCM)/brake pressure modulator (BPMV) must be free from loose dirt to prevent contamination of the disassembled ABS components.
Thoroughly wash all contaminants from around the EBCM/BPMV.
Rotate the EBCM connector tab up to the unlocked position.
Remove the EBCM connector position assurance (2) from the EBCM electrical connector (1). CAUTION: To prevent equipment damage, never connect or disconnect the wiring harness connection from the EBCM with the ignition switch in the ON position.
Disconnect the EBCM electrical connector (1) from the EBCM (4). WARNING: Brake fluid may irritate eyes and skin. In case of contact, take the following actions: Eye contact-rinse thoroughly with water. Skin contact-wash with soap and water. If ingested-consult a physician immediately. CAUTION: When removing the brake pressure modulator valve, protect the vehicle exterior from possible brake fluid spillage. Brake fluid can cause damage to painted surfaces. CAUTION: Excessive bending of brake pipes during BPMV removal or installation may cause permanent damage that will require replacement. NOTE: Record the location of all brake pipes to the BPMV for use as an aid during installation.
Remove the 2 master cylinder brake pipes (1) from the BPMV (2).
Remove the 4 wheel brake pipes (1) from the BPMV (2).
Clean any brake fluid spillage from the BPMV (1).
Remove the 2 BPMV bracket nuts (2).
Remove the EBCM/BPMV assembly (1) from the BPMV bracket (3).
Disconnect the BPMV electrical connector (2) from the EBCM (3).
Remove the 6 EBCM to BPMV screws (2).
Clean the surface of the EBCM/BPMV assembly. NOTE: The EBCM cannot be repaired. If faulty, the unit must be replaced.
Separate the EBCM (2) from the BPMV (1).

Scheme 85

Scheme 85: Installation Procedure

Scheme 86

Scheme 87

Scheme 88

Clean the seal surface of the Brake Pressure Modulator (BPMV).
Install the Electronic Brake Control Module (EBCM) (2) to the BPMV (1). CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the 6 EBCM to BPMV screws (2). Tighten the 6 screws to 3.2 N.m (28 lb in).
Connect the BPMV electrical connector (2) to the EBCM (3). NOTE: Make sure that all 3 rubber isolators are installed on the BPMV. The isolators protect the EBCM/BPMV assembly from vehicle vibrations.
Install the EBCM/BPMV assembly (1) to the BPMV bracket (3). CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the 2 BPMV bracket nuts (2). Tighten the 2 nuts to 10 N.m (89 lb in). WARNING: Make sure brake pipes are correctly connected to BPMV. If brake pipes are switched by mistake Inlet vs. Outlet, wheel lockup will occur and personal injury may result. NOTE: If a new BPMV is being installed, remove the shipping plugs from the valve openings.
Install the 4 wheel brake pipes (1) to the BPMV (2) using the locations recorded during the removal procedure. Tighten the 4 brake pipes to 15 N.m (11 lb ft).
Install the 2 master cylinder brake pipes (1) to the BPMV (2) using the locations recorded during the removal procedure. Tighten the 2 brake pipes to 15 N.m (11 lb ft). CAUTION: To prevent equipment damage, never connect or disconnect the wiring harness connection from the EBCM with the ignition switch in the ON position.
Connect the EBCM electrical connector (1) to the EBCM (4).
Install the EBCM connector position assurance (2) to the EBCM electrical connector (1).
Rotate the EBCM connector tab (2) down to the locked position.
Install the left front wheelhouse extension. Refer to «FASCIA EXTENSION REPLACEMENT - FRONT»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#bumper-system) in Bumpers.
Install the left front wheel.
Lower the vehicle.
Fill and bleed the hydraulic brake system. Refer to «MASTER CYLINDER RESERVOIR»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes) and «MANUAL BLEEDING»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__manual-bleeding) or «PRESSURE BLEEDING»(/buick/lesabre/viii-2000-2005/remont/mechanical-hydraulic/#disc-brakes__pressure-bleeding) in Disc Brakes.
Perform the Auto Bleed Procedure. Refer to «ABS AUTOMATED BLEED PROCEDURE»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .
Perform the ABS Diagnostic System Check. Refer to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Raise the vehicle.
Remove the left front wheel.
Remove the left front wheelhouse extension. Refer to «FASCIA EXTENSION REPLACEMENT - FRONT»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#bumper-system) in Bumpers. NOTE: The area around the Electronic Brake Control Module (EBCM)/Brake Pressure Modulator (BPMV) must be free from loose dirt to prevent contamination of disassembled ABS components.
Thoroughly wash all contaminants from around the EBCM/BPMV.
Remove the 2 BPMV bracket nuts (2).
Remove the 3 BPMV bracket to frame bolts (2).
Remove the BPMV bracket (1) from the frame (3).

Scheme 89

Scheme 89: Installation Procedure

Install the Brake Pressure Modulator (BPMV) bracket (1) to the frame (3). CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the 3 BPMV bracket to frame bolts (2). Tighten the 3 bolts to 12 N.m (106 lb in). NOTE: Make sure that all 3 rubber isolators are installed on the BPMV. The isolators protect the Electronic Brake Control Module (EBCM)/BPMV assembly from vehicle vibrations.
Install the EBCM/BPMV assembly (1) to the BPMV bracket (3).
Install the 2 BPMV bracket nuts (2). Tighten the 2 nuts to 10 N.m (89 lb in).
Install the left front wheelhouse extension. Refer to «FASCIA EXTENSION REPLACEMENT - FRONT»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#bumper-system) in Bumpers.
Install the left front wheel.
Lower the vehicle.

Note. The wheel speed sensor wiring is included in the engine harness. The wiring between the wheel speed sensor and the heat shrink sealed splices is high-flex cable and must not be repaired or spliced. This procedure replaces the high-flex cable with a jumper harness from a supplied repair kit.

Turn OFF the ignition.
Raise the vehicle.
Remove the left front wheel.
Remove the wheel speed sensor connector (7) from the wheel speed sensor (6).
Remove the harness grommet (3) from the strut bracket (5).
Remove the harness grommet (1) from the rail bracket (2).
Remove the harness clip (4) from the rail bracket (2).
Route the wheel speed sensor wiring (8) through the top of the engine compartment.
Lower the vehicle.
Cut the engine harness conduit (1) at the shown location to locate the 2 heat shrink sealed splices.

Installation Procedure

Replace the wheel speed sensor jumper harness. Refer to «WIRING REPAIRS»(/buick/lesabre/viii-2000-2005/remont/accessories-control-systems/#wiring-systems-general-information__wiring-repairs) in Wiring Repair.
Route the wheel speed sensor jumper (1) through the engine compartment to the wheel well.
Raise the vehicle.
Install the wheel speed sensor connector (7) to the wheel speed sensor (6).
Install the harness grommet (3) to the strut bracket (5).
Install the harness grommet (1) to the rail bracket (2).
Install the harness clip (4) the rail bracket (2).
Install the left front wheel.
Lower the vehicle.
Perform the ABS Diagnostic System Check. Refer to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Turn OFF the ignition.
Raise the vehicle.
Remove the right front wheel.
Remove the wheel speed sensor connector (7) from the wheel speed sensor (6).
Remove the harness grommet (3) from the strut bracket (5).
Remove the harness grommet (1) from the rail bracket (2).
Remove the harness clip (4) from the rail bracket (2).
Cut the engine harness conduit (1) to locate the 2 heat shrink sealed splices.

Replace the wheel speed sensor jumper harness. Refer to «WIRING REPAIRS»(/buick/lesabre/viii-2000-2005/remont/accessories-control-systems/#wiring-systems-general-information__wiring-repairs) in Wiring Systems.
Install the wheel speed sensor connector (7) to the wheel speed sensor (6).
Install the harness grommet (3) to the strut bracket (5).
Install the harness grommet (1) to the rail bracket (2).
Install the harness clip (4) to the rail bracket (2).
Install the right front wheel.
Lower the vehicle.
Perform the ABS Diagnostic System Check. Refer to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Turn OFF the ignition.
Remove the rear seat cushion. Refer to «SEAT CUSHION REPLACEMENT - REAR»(/buick/lesabre/viii-2000-2005/remont/seats/#power-seat-system) in Seats.
Disconnect the lateral accelerometer sensor electrical connector (2).
Remove the 2 lateral accelerometer sensor screws (3).
Remove the lateral accelerometer sensor (1).

Scheme 90

Scheme 90: Installation Procedure

Install the lateral accelerometer sensor (1). CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the 2 lateral accelerometer sensor screws (3). Tighten the 2 lateral accelerometer sensor screws to 2.4 N.m (21 lb in).
Connect the lateral accelerometer sensor electrical connector (2).
Install the rear seat cushion. Refer to «SEAT CUSHION REPLACEMENT - REAR»(/buick/lesabre/viii-2000-2005/remont/seats/#power-seat-system) in Seats.
Perform the ABS Diagnostic System Check. Refer to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Turn OFF the ignition.
Remove the rear compartment front trim panel. Refer to «COMPARTMENT TRIM PANEL REPLACEMENT - REAR»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#body-rear-end) in Body Rear End.
Remove the rear shelf trim panel. Refer to «TRIM PANEL REPLACEMENT - REAR WINDOW SHELF»(/buick/lesabre/viii-2000-2005/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
Remove the 2 yaw rate sensor mounting nuts (1).
Remove the yaw rate sensor (2).
Disconnect the yaw rate sensor electrical connector (3).

Scheme 91

Scheme 91: Installation Procedure

Install the yaw rate sensor electrical connector (3). CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the yaw rate sensor (2). Tighten the 2 yaw rate sensor mounting nuts (1) to 6 N.m (53 lb in).
Install the rear shelf trim panel. Refer to «TRIM PANEL REPLACEMENT - REAR WINDOW SHELF»(/buick/lesabre/viii-2000-2005/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
Install the rear compartment front trim panel. Refer to «COMPARTMENT TRIM PANEL REPLACEMENT - REAR»(/buick/lesabre/viii-2000-2005/remont/exterior-body-panels/#body-rear-end) in Body Rear End.
Perform the ABS Diagnostic System Check. Refer to «DIAGNOSTIC SYSTEM CHECK - ABS»(/buick/lesabre/viii-2000-2005/remont/anti-locktraction-control/#anti-lock-brake-system) .

Scheme 92

Scheme 92: ABS DESCRIPTION & OPERATION

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This vehicle is equipped with the Delco/Bosch 5.3 anti-lock braking system.

The vehicle is equipped with the following braking systems

Anti-Lock Brake System (ABS).
Dynamic Rear Proportioning (DRP).
Traction Control System (TCS) (w/NW9).
Vehicle Stability Enhancement System (VSES) (w/JL4).

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

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 connector, is an opening to the internal cavity of the EBCM. It allows ventilation of the EBCM internals.
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. NOTE: 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).
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.
Traction Control Switch (w/NW9) - The TCS is manually disabled or enabled using the traction control switch.
Stop lamp Switch - The EBCM uses the stop lamp switch as an indication that the brake pedal is applied.
Lateral Accelerometer Sensor (w/JL4) - The EBCM uses the lateral accelerometer sensor as an indication of the lateral acceleration of the vehicle.
Yaw Rate Sensor (w/JL4) - The EBCM uses the yaw rate sensor as an indication of the yaw rate of the vehicle.
Steering Wheel Position Sensor (SWPS) (w/JL4) - The EBCM uses the SWPS as an indication of the position and rotation of the steering wheel.

Initialization Sequence

The EBCM performs 1 initialization test each ignition cycle. The initialization of the EBCM occurs when 1 set of the following conditions occur

Both of the following conditions occur

The EBCM detects that there is a minimum of 500 RPM from the PCM via a serial data message.
The stop lamp switch is not applied.

Both of the following conditions occur

The vehicle speed is greater than 16 km/h (10 mph).
The stop lamp switch 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 anti-lock mode. During anti-lock 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 anti-lock 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 EBCM responds to wheel speed sensor inputs and attempts to prevent wheel slip. These pedal pulsations are present only during anti-lock 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 anti-lock braking on dry pavement, intermittent chirping noises may be heard as the tires approach slipping. These noises and pedal pulsations are considered normal during anti-lock 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 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 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 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 mechanical proportioning valve in the base brake system. The DRP control system is part of the operation software in the EBCM. The DRP uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.

The red brake warning indicator is illuminated when the dynamic rear proportioning function is disabled.

Traction Control System (TCS) (NW9)

When drive wheel slip is noted while the brake is not applied, the EBCM will enter traction control mode.

First, the EBCM requests the PCM to reduce the amount of torque to the drive wheels via the requested torque signal circuit. The PCM reduces torque to the drive wheels by retarding spark timing and turning off fuel injectors. The PCM reports the amount torque delivered to the drive wheels via the delivered torque signal circuit.

If the engine torque reduction does not eliminate drive wheel slip, the EBCM will actively apply the drive wheel brakes. During traction control braking, hydraulic pressure in each drive wheel circuit is controlled to prevent the drive wheels from slipping. The master cylinder isolation valve closes in order to isolate the master cylinder from the rest of the hydraulic system. The prime valve then opens in order to allow the pump to accumulate brake fluid in order to build hydraulic pressure for braking. The drive wheel inlet and outlet solenoid valves then open and close in order to perform the following functions

Pressure hold.
Pressure increase.
Pressure decrease.

Vehicle Stability Enhancement System (VSES)

The Vehicle Stability Enhancement System (VSES) includes an additional level of vehicle control to the EBCM. The VSES is activated by the 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 left or right front wheel.

Brake System Indicator

The IPC illuminates the brake indicator when any of the following occur

The IPC detects that the park brake is engaged. If the vehicle travels 3-15.2 m (10-50 ft) with the park brake engaged, the IPC sends a class 2 message to the BCM in order to activate an audible warning.
The IPC detects a low brake fluid condition. The IPC sends a class 2 message to the BCM in order to activate an audible warning.
The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 5 seconds.
The IPC detects a loss of class 2 communications with the EBCM and the discrete back-up ABS indicator signal circuit is high.

ABS Indicators

The IPC illuminates the ABS indicator when the following occurs

The Electronic Brake Control Module (EBCM) detects a malfunction with the anti-lock brake system. The IPC receives a class 2 message from the EBCM requesting illumination.
The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 5 seconds.
The IPC detects a loss of class 2 communications with the EBCM and the discrete back-up ABS indicator signal circuit is high.

When the ABS indicator is commanded on, the IPC also illuminates the TRAC OFF indicator and illuminates the SERVICE STABILITY SYSTEM indicator in the DIC.

TRAC OFF

The IPC illuminates the TRAC OFF indicator when any of the following occur

The Electronic Brake Control Module (EBCM) inhibits the traction control system due to a malfunction in the traction control system. The IPC receives a class 2 message from the EBCM requesting illumination. The IPC sends a class 2 message to the BCM in order to activate an audible warning.
The EBCM detects that the traction control switch is pressed. The IPC receives a class 2 message from the EBCM indicating the switch status.
The IPC receives a class 2 message from the EBCM requesting illumination of the ABS indicator.
The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 5 seconds.

TRACTION CONTROL SYSTEM ACTIVE - 91

The IPC illuminates the TRACTION CONTROL SYSTEM ACTIVE - 91 message in the DIC when the Electronic Brake Control Module (EBCM) detects that the traction control system is active. The IPC receives a class 2 message from the EBCM requesting illumination.

STABILITY SYSTEM ACTIVE - 55 (with DIC)

The IPC illuminates the STABILITY SYSTEM ACTIVE - 55 indicator in the DIC when the Electronic Brake Control Module (EBCM) detects that the enhanced stability system, the ABS system, or the traction control system is active. The IPC receives a class 2 message from the EBCM requesting illumination. The LOW TRAC indicator also illuminates when the STABILITY SYSTEM ACTIVE - 55 indicator illuminates.

SERVICE STABILITY SYSTEM - 54 (with DIC)

The IPC illuminates the SERVICE STABILITY SYSTEM - 54 indicator in the DIC when the following occurs

The Electronic Brake Control Module (EBCM) detects a malfunction in the enhanced stability system. The IPC receives a class 2 message from the EBCM requesting illumination. The IPC sends a class 2 message to the radio in order to activate an audible warning.
The IPC detects a loss of class 2 communications with the EBCM and the discrete back-up ABS indicator signal circuit is high.

TIRE PRESSURE MONITOR DESCRIPTION & OPERATION

The Tire Pressure Monitor (TPM) system alerts the driver when a large change in the pressure of one tire exists while the vehicle is being driven. The TPM system uses the Electronic Brake Control Module (EBCM), ABS wheel speed sensor inputs, class 2 serial data circuit, and the Driver Information Center (DIC) to perform the system functions. The EBCM contains software to calculate relative tire pressure differences. The software requires approximately 30 minutes of straight line driving in each of the 3 speed ranges to complete the calibration process to have full capability for detecting a tire pressure condition. The speed ranges are as follows

24-64 km/h (15-40 mph)
64-113 km/h (40-70 mph)
113-145 km/h (70-90 mph)

Each speed range has 2 modes of tire pressure detection

Monitor Mode 1
Monitor Mode 2

The EBCM learns the tire pressure configuration for each speed range independently. In Monitor Mode 1, the EBCM has only partially learned the tire pressure calibration for the speed range and has limited detection capability for a tire pressure conditions. In Monitor Mode 2, the EBCM has fully learned the tire pressure calibration for the speed range and has full detection capability for a tire pressure condition. Once the TPM system has learned the tire pressure calibration the EBCM monitors the ABS wheel speed sensor inputs, which will all be the same as the learned calibration if the tire pressures stay the same. If the pressure in one tire increases or decreases so too will that tire's circumference and radius, which causes that wheel speed sensor input to change. The EBCM recognizes this change in wheel speed as a tire pressure condition. If the pressure in one tire becomes at least 69 kPa (10 psi) lower or higher than the other three the EBCM commands the DIC to display the CHECK TIRE PRESSURE warning message via a class 2 serial data circuit. This message does not appear if more than one tire pressure is high or low, or if the system is not calibrated properly. The system does not alert the driver to which tire pressure is high or low. If the tire pressures are at the specified pressure TIRE PRESSURE NORMAL is displayed when selected on the DIC. To clear the CHECK TIRE PRESSURE message refer to TIRE PRESSURE MONITOR RESET PROCEDURE .

Scheme 94

Scheme 94: SPECIAL TOOLS & EQUIPMENT

Anti-Lock Brake System Buick LeSabre VIII

FASTENER TIGHTENING SPECIFICATIONS

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Circuit Description

Test Description

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DIAGNOSTIC SYSTEM CHECK - TIRE PRESSURE MONITORING

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SCAN TOOL DATA DEFINITIONS

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DIAGNOSTIC TEST DRIVE

History Data

Diagnostic Strategy

Conditions For Running DTC

Conditions For Setting DTC

Action Taken When DTC Sets

Conditions For Clearing DTC

Diagnostic Aids

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C1221 Through C1228

C1232 Through C1235

C1221 Through C1224

C1225 Through C1228

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C1242

C1243

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Actions Taken When DTC Sets

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C1255

C1256

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C1276

P1644 Or P1689

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C1277