Mazda Training manual — part 91

Dynamic Driving Safety Systems

ABS

•

The ABS warning light is either hardwired to the ABS control module or switched from a
microcomputer in the IC. In the second case the IC receives an ABS warning light ON
request via CAN if the ABS CM detects a malfunction.

•

If there is an open circuit between the ABS CM and the IC, the ABS warning light will be
illuminated by the microcomputer or a transistor inside the IC. On earlier models a short-
circuit bridge was installed to the connector of the ABS CM to ensure that the warning
light is illuminated if the connector is disconnected.

L2003_02015

CAN controlled

1

Brake system warning light

5

CAN driver

2

ABS warning light

6

CAN H

3 IC

7 CAN

L

4 ABS

HU/CM

Curriculum Training

02-23

ABS

Dynamic Driving Safety Systems

L2003_02047

Hard wired transistor controlled

1

ABS warning light

3

ABS CM

2 IC

Diagnostics

•

The ABS warning light can be checked by:

–

Visually inspecting the warning light after switching the ignition on

–

Checking voltage signals

–

Using the input/output check mode for the IC

–

Monitoring the corresponding PID (see below)

PID

Definition Unit/Condition

ABS_LMP

ABS warning light

ON/OFF

L2003_T02023

02-24 Curriculum

Training

Dynamic Driving Safety Systems

ABS

ABS on Vehicles with 4WD

•

The ABS on vehicles with 4WD (4 Wheel Drive) is essentially the same as on other
vehicles, except for the following features:

–

A G-sensor (Gravity) has been installed on vehicles with 4WD.

–

On the Mazda6, 4WD operation is disabled during ABS operation. To do so, the ABS
HU/CM transmits a signal via CAN to the 4WD CM, and the 4WD CM
correspondingly disables the electronically controlled clutch.

G-Sensor

•

On the B-Series the G-sensor is mounted under the passenger’s seat, and on Mazda6 it
is incorporated in the combined sensor, while on Tribute it is integrated in the ABS
HU/CM.

•

The G-sensor features a longitudinal accelerometer and is connected to the ABS
HU/CM. It sends an acceleration/deceleration signal to the CM.

•

The signal from the G-sensor is necessary as a vehicle speed correction factor.
Because, on 4WD vehicles, under some circumstances, the movement of the vehicle
cannot be measured as precisely as necessary when using the wheel speed sensors
only.

L2003_02016

1

Front of vehicle

4

Acceleration

2 G-Sensor

5 Neutral-G

3

Output voltage characteristics

6

Deceleration

Curriculum Training

02-25

ABS

Dynamic Driving Safety Systems

L2003_02055

1 G-sensor

2 ABS

HU/CM

Diagnostics

•

The G-sensor and 4WD related components can be checked by:

–

Reading out DTCs

–

Checking the voltage signal

–

Monitoring the corresponding PIDs (see below)

PID

Definition Unit/Condition

ACCLMTR

Longitudinal acceleration in G

G

AWD_MSG Communication with 4WD CM (only on Mazda6)

Present / Not Present

L2003_T02012

Replacement

•

If the G-sensor on a Mazda6 needs to be replaced, the new sensor must be initialised
using the M-MDS (refer to W/M).

02-26 Curriculum

Training