Mazda 3 Service Manual: ABS HU/CM Inspection

Mazda 3 Service Manual / Brakes / Brake Control, Vehicle Dynamics / Sensors, Switches, Relays / ABS HU/CM Inspection

1. Disconnect the ABS HU/CM connector..

2. Connect the negative battery cable..

3. Attach the tester lead to the ABS HU/CM wiring harness-side connector and inspect the voltage, continuity, or resistance according to the standard (reference value) in the table below.

Standard (reference)


Terminal	Signal name	Connected to	Measured item	Measured terminal (measurement condition)	Standard	Inspection item(s)
A	−	−	−	−	−	−
B	Ground	Ground point	Continuity	B—ground point	Continuity detected	Wiring harness (B—ground point)
C	RR wheel-speed (-)	RR ABS wheel-speed sensor	Continuity	C–RR ABS wheel-speed sensor connector terminal B	Continuity detected	Wiring harness (C–RR ABS wheel-speed sensor connector terminal B)
D	−	−	−	−	−	−
E	RR wheel-speed (+)	RR ABS wheel-speed sensor	Continuity	E–RR ABS wheel-speed sensor connector terminal A	Continuity detected	Wiring harness (E–RR ABS wheel-speed sensor connector terminal A)
F	−	−	−	−	−	−
G	−	−	−	−	−	−
H	CAN_H	DLC-2 (CAN_H)	This terminal is used for communication and cannot be used for malfunction determination during terminal voltage inspection.Perform a DTC inspection.
I	LF wheel-speed (+)	LF ABS wheel speed sensor	Continuity	I–LF ABS wheel-speed sensor connector terminal A	Continuity detected	Wiring harness (I–LF ABS wheel-speed sensor connector terminal A)
J	−	−	−	−	−	−
K	LF wheel-speed (-)	ABS wheel-speed sensor (LF)	Continuity	K–LF ABS wheel-speed sensor connector terminal B	Continuity detected	Wiring harness (K–LF ABS wheel-speed sensor connector terminal B)
L	CAN_L	DLC-2 (CAN_L)	This terminal is used for communication and cannot be used for malfunction determination during terminal voltage inspection.Perform a DTC inspection.
M	−	−	−	−	−	−
N	Power supply (System)	Ignition switch or IG1 relay	Voltage	Switch the ignition to ON	B+	Wiring harness (N—ignition switch or IG1 relay)
N	Power supply (System)	Ignition switch or IG1 relay	Voltage	Switch the ignition to off	1 V or less	Wiring harness (N—ignition switch or IG1 relay)
O	RF wheel-speed (-)	RF ABS wheel-speed sensor	Continuity	O–RF ABS wheel-speed sensor terminal B	Continuity detected	Wiring harness (O–RF ABS wheel-speed sensor connector terminal B)
P	−	−	−	−	−	−
Q	RF wheel-speed (+)	RF ABS wheel-speed sensor	Continuity	Q–RF ABS wheel-speed sensor terminal A	Continuity detected	Wiring harness (Q–RF ABS wheel-speed sensor connector terminal A)
R	−	−	−	−	−	−
S	−	−	−	−	−	−
T	−	−	−	−	−	−
U	LR wheel-speed (+)	LR ABS wheel-speed sensor	Continuity	U–LR ABS wheel-speed sensor connector terminal A	Continuity detected	Wiring harness (U–LR ABS wheel-speed sensor connector terminal A)
V	−	−	−	−	−	−
W	LR wheel-speed (-)	LR ABS wheel-speed sensor	Continuity	W–LR ABS wheel-speed sensor connector terminal B	Continuity detected	Wiring harness (W–LR ABS wheel-speed sensor connector terminal B)
X	−	−	−	−	−	−
Y	Power supply (Solenoid operation, ABS motor operation)	Battery	Voltage	Under any condition	B+	Wiring harness (Y–battery)
Z	−	−	−	−	−	−

Sensors, Switches, Relays

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ABS HU/CM Removal/Installation

WARNING: If the ABS HU/CM configuration is not completed, it could result in an unexpected accident due to the ABS being inoperative. If the ABS HU/CM or ABS CM is replaced, always use t ...

Other materials:

Parking Brake
CAUTION Driving with the parking brake on will cause excessive wear of the brake parts. NOTE For parking in snow, refer to Winter Driving regarding parking brake use. Setting the parking brake Depress the brake pedal and then firmly pull the parking brake lever fully upwar ...

Battery Inspection [Mzr 2.0, Mzr 2.5]
WARNING: Since battery acid is toxic, be careful when handling the battery. Since battery acid is highly corrosive, be careful not to allow it to contact clothing or the vehicle. In case battery acid contacts skin, eyes, or clothing, flush it immediately with running wa ...

Tachometer
The tachometer shows engine speed in thousands of revolutions per minute (rpm). CAUTION Do not run the engine with the tachometer needle in the RED ZONE. This may cause severe engine damage. Type A *1 The range varies depending on the type of gauge. Type B *1 The ...