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ABS HU/CM DESCRIPTION

BME041343750T01
• The ABS HU/CM detects wheel-speed and driving condition based on the ABS wheel-speed sensors, and outputs on/off electronic signals to the inlet solenoid valves and outlet solenoid valves to control the following functions.

  - 4-sensor, 3-channel select low control ABS control
  - Electronic Brakeforce Distribution (EBD) control uses a 4 sensor, 4-channel system

• CPU1 and CPU2 in the ABS HU/CM monitor each other for ABS HU/CM safety. The function of CPU1 and CPU2 is as follows.

  - CPU1 controls the ABS operation by activating the pressure and outlet solenoid valves based on the signals from each wheel-speed sensor.
  - CPU2 has a self-diagnosis function that monitors the system operation and input/output signals from CPU1. When CPU2 detects system failure, the watch-dog sends (ABS motor and fail-safe) a signal to turn off the relay (ABS motor and fail-safe). As a result, ABS and EBD operation is stopped and shifts to fail-safe mode.

• The ABS HU/CM constantly calculates the average value of the signals from the front ABS wheel-speed sensors and sends a vehicle speed signal to the instrument cluster.

  - The ABS HU/CM constantly sends the average value of the two sensors on either side. In case a malfunction occurs in one of the sensors, however, the ABS sends a value from only the normal sensor.

## Block Diagram

1 | Battery
2 | ABS wheel-speed sensor
3 | Brake switch
4 | Voltage regulator
5 | ABS wheel-speed sensor input interface
6 | Switch input interface
7 | DTC memory
8 | CPU1
9 | CPU2
10 | Watch-dog
11 | Warning light drive
12 | Solenoid drive
13 | Solenoid monitor
14 | Motor monitor
15 | Relay drive
16 | Solenoid valve
17 | ABS motor
18 | ABS relay
19 | DLC
20 | BRAKE system warning light
21 | ABS warning light
22 | Speed signal output drive
23 | ABS HU/CM
24 | ABS CM
25 | ABS HU
26 | Instrument cluster (Speedometer)
27 | DLC-2