Scheme 1
Principles of Operation
The anti-lock brake control module manages anti-lock braking with traction control and stability assist, also manages traction control and engine control systems to maintain vehicle control during deceleration and acceleration.
When the ignition switch is put in the RUN position, the module will do a preliminary electrical check, and at approximately 20 km/h (12 mph), the hydraulic pump motor is turned on for approximately one half-second. Any malfunction of the anti-lock brake control system will disable the traction control and stability assist and the anti-lock brake warning indicator will illuminate. However, the power-assist braking system will function normally.
Normal Operation
The operating voltage required to supply the ABS module, hydraulic pump, and isolation valves is in a range between 10 and 17 volts.
Voltage is supplied by circuit 533 (TN/RD) (ignition feed) and circuit 534 (YE/LG) (power hot at all times). Ground is provided through circuit 530 (LG/YE).
The operating voltage required to supply the brake pedal position (BPP) switch is 5 volts through circuit 1902 (RD).
The BPP signal is sent through circuit 1905 (GY) to the ABS module.
Ground is provided through circuit 1904 (GY/BK).
The vehicle electrical system supplies 12 volts to the ABS module.
Voltage is supplied by circuit 533 (TN/RD) (ignition feed) and circuit 534 (YE/LG) (power hot at all times). Ground is provided through circuit 530 (LG/YE).
The operating voltage required to run the hydraulic pump motor is in a range between 10 and 17 volts.
Voltage is supplied by circuit 534 (YE/LG) (power hot at all times). Ground is provided through circuit 530 (LG/YE).
The active wheel speed sensor generates a square wave signal that is sent to the ABS module. The wheel speed sensor circuitry connects to the ABS module connector C155 through two wires and a connector at each wheel speed sensor. When the ignition is turned to the RUN position, the ABS module carries out a self-test by sending a reference voltage through the right front wheel speed sensor and its circuitry to determine if they are functional.
Twelve volts are supplied to the active wheel speed sensors from the ABS module. The wheel speed sensor ground is supplied by the ABS module.
The wheel speed sensor and sensor ring generate a square wave signal to the ABS module that is proportional to wheel speed. The ABS module compares wheel speed inputs from all wheel speed sensors to determine an impending wheel lockup.
The steering wheel rotation sensor monitors the steering wheel position when the toothed-wheel on the steering shaft passes through its magnetic field.
Steering wheel rotation (in degrees) is sent to the ABS module through circuit 1572 (DG) and circuit 1573 (YE). Voltage is supplied by the ABS module through circuit 1574 (DB). Ground is provided by the ABS module through circuit 1571 (BK).
The accelerometer (lateral and longitudinal-4x4) and the yaw rate sensor are contained in the sensor cluster. The sensor measures the vehicle acceleration and yaw rate then sends the signal via CAN communication wires to the ABS module.
Voltage is supplied by circuit 1574 (DB). Ground is provided through circuit 1575 (WH/BK). The CAN communication is transmitted through circuit 1878 (TN/YE) and circuit 1879 (RD/YE).
The active brake booster has internal solenoids that assist driver brake applications or can apply the brakes when needed if the vehicle loses control.
Power is supplied by circuit 1582 (LG/RD). Ground is provided through circuit 1583 (BK/WH).
The active brake booster has a normally open (NO), and a normally closed, (NC) pedal force switch that operates according to driver brake applications.
The NO pedal force switch circuit is 1581 (PK/LB). The NC pedal force switch circuit is 1580 (WH/LG).
The brake pressure transducer sends current to the ABS module proportional to the driver's brake pedal application.
Reference voltage is supplied by circuit 3601 (WH/RD). Ground is provided through circuit 3603 (RD). The transducer current is supplied by circuit 3600 (RD/WH).
The 5 volt reference voltage is supplied by the Anti-Lock Brake Module (ABS).
Reference voltage is supplied by circuit 3601 (WH/RD). The reference voltage circuit returns to the ABS module through the BPP switch circuit 1904 (GY/BK) and the brake pressure transducer circuit 3603 (RD).
The 12 volt driver brake apply (DBA) signal is sent from the ABS module during brake application to the trailer tow relay (if equipped).
Voltage is supplied by circuit 1791 (RD).
Engine torque modulation is achieved by regulating fuel and spark to the cylinders. The Advance Trac system operates using the ABS module to interact with the PCM to reduce engine torque if one or both rear wheels lose traction and begin to spin during acceleration.
Voltage is supplied by circuit 959 (GY/BK). Ground is provided through circuit 1205 (BK).
Engine torque modulation is achieved by regulating fuel and spark to the cylinders. The Advance Trac system operates using the ABS module to interact with the PCM to reduce engine torque if one or both rear wheels lose traction and begin to spin during acceleration.
Voltage is supplied by circuit 959 (GY/BK). Ground is provided through circuit 1205 (BK). The switch illumination off circuit is 960 (BK/LB).
The brake pressure switch provides an additional speed control deactivation if the brake ON/OFF (BOO) switch fails. When the brake pedal is pressed, 125 psi of brake fluid pressure in the brake master cylinder opens the brake pressure switch, removing B+ voltage to the speed control servo electric clutch.
The Advance Trac(R)/IVD system needs to be recalibrated whenever a component specific to the system is disconnected or a new component is installed.
The yaw rate sensor and accelerometer are part of the sensor cluster which sends various signals about the vehicle's dynamics through a two-wire bus CAN HI 3126 (TN/YE) and CAN LOW 3125 (RD/YE). The CAN bus receives a twelve-volt input through circuit 1574 (DB) in series with the steering wheel rotation sensor circuitry. Ground is provided through circuit 1575 (BK/WH).