Honda Civic. Manual — part 6

Fig. 4: Identifying ABS Modulator-Control Unit Inputs And Outputs For 25P
Connector

ABS MODULATOR-CONTROL UNIT INPUTS AND OUTPUTS FOR 25P
CONNECTOR

Terminal

number

Wire
color

Terminal

sign

Description

Measurement (Disconnect the

ABS modulator-control unit

25P connector)

Terminal Conditions

Results

1

WHT CAN-H

F-CAN
communication
circuit

-

-

-

2

GRN

FR+B

Detects right-
front wheel
sensor signal

-

-

-

3

GRY FL-GND

Detects left-
front wheel
sensor signal

-

-

-

5

PUR RL-GND

Detects left-rear
wheel sensor
signal

-

-

-

6

LT

GRN

RR+B

Detects right-
rear wheel
sensor signal

-

-

-

8

WHT FSR+B

Power source
for the fail-safe
relay

8-GND

At all times

Battery
voltage

9

RED

MR+B

Power source
for the motor

9-GND

At all times

Battery

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

SYSTEM OUTLINE

This system is composed of the ABS modulator-control unit, the wheel sensors, and
the system indicators in the gauge control module. The ABS modulator-control unit
controls the anti-lock brake and the brakes distribution functions.

relay

voltage

10

LT

BLU

K-LINE

Communication
with HDS

-

-

-

12

ORN

FL+B

Detects left-
front wheel
sensor signal

-

-

-

14

BLU

RL+B

Detects left-rear
wheel sensor
signal

-

-

-

15

WHT RR-GND

Detects right-
rear wheel
sensor signal

-

-

-

16

GRY

IG1

Power source
for activating
the system

16-GND

Ignition
switch

ON (II)
Battery
voltage

17

RED CAN-L

F-CAN
communication
circuit

-

-

-

18

PNK FR-GND

Detects right-
front wheel
sensor signal

-

-

-

24

BLK

GND

Ground for the
ABS modulator-
control unit

24-GND At all times Continuity

25

BLK MR-GND

Ground for the
pump motor

25-GND At all times Continuity

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

Fig. 5: Identifying ABS Modulator-Control Unit System Outline

ABS FEATURES

Without ABS, when the brake pedal is pressed while driving, the wheels sometimes
lock before the vehicle comes to a stop. In such an event, the maneuverability of the
vehicle is reduced if the front wheels are locked, and the stability of the vehicle is
reduced if the rear wheels are locked, creating an extremely unstable condition.
With ABS, the system precisely controls the slip rate of the wheels to ensure
maximum grip force from the tires, and it thereby ensures maneuverability and
stability of the vehicle. The ABS calculates the slip rate of the wheels based on the
four wheel speeds, then it controls the brake fluid pressure to reach the target slip
rate.

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)

Fig. 6: Identifying Grip Force Of Tire And Road Surface

The control unit detects the wheel speed based on the wheel sensor signals it
received, then it calculates the vehicle speed based on the detected wheel speed.
The control unit detects the vehicle speed during deceleration based on the rate of
deceleration.

The control unit calculates the slip rate of each wheel, and transmits the control
signal to the modulator unit solenoid valve when the slip rate is high.

The hydraulic control has three modes: Pressure intensifying, pressure reducing,
and pressure retaining.

Fig. 7: Identifying Hydraulic Control Unit Flow Diagram

2008 Honda Civic GX

2006-08 BRAKES ABS System - Civic (All Except Hybrid)