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EBD CONTROL OPERATION

id041300185700
• EBD control detects the slip ratio between the front and rear wheels from the ABS wheel-speed sensor signals. If the slip ratio of the rear wheels as compared to the front wheels is larger than the fixed limit, the ABS (ABS/TCS) HU/CM reduces brake pressure being distributed to the rear wheels. Due to this, brake pressure distribution is constantly controlled in the proper proportion and in relation to vehicle load, road surface conditions and vehicle speed.
• Determination of the rear wheel slip ratio, based on a comparison of the lowest front wheel speed and the estimated vehicle speed with the rear wheel speeds, is divided into conditions 0-4 shown in the table below.
• The ABS (ABS/TCS) HU outlet and inlet solenoid valves are operated and the brake fluid pressure controlled according to these conditions.
• If ABS control conditions are met during EBD control, EBD control is stopped and ABS control is given priority.

Status | Rear wheel slip ratio determination | EBD control | Solenoid valve | Comment
--- | --- | --- | --- | ---
0 | No slip | No control | Pressure increase | -
1 | a%-b% | Control | Pressure maintained | -
2 | b% or more | Control | Reduction/maintained | -
3 | After EBD control, slip ratio is g% | Control | Increase/maintain | -
4 | Front wheel slip ratio is d% or more | Control | Pressure reduction/maintained/ increase | ABS control operates

  a-d :
Specified value

## Operating Condition Transition Diagram

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1 | Speed
2 | EBD initial control value
3 | ABS initial control value
4 | Vehicle speed
5 | Rear wheel speed
6 | Front wheel speed
7 | High
8 | Time
9 | Rear solenoid valve control
10 | Brake fluid pressure
11 | Pressure reduction
12 | Pressure maintained
13 | Pressure increase
14 | EBD control area
15 | ABS control area
16 | Front brake fluid pressure
17 | Rear brake fluid pressure