ABS HU/CM INSPECTION

BME041367650201

1. Remove the battery and battery tray.

2. Connect the SST between the ABS HU/CM and harness connector with the ignition switch off.

3. Attach the tester leads to the SST to inspect voltage by referring to the table below.

Caution
• In the event that the vehicle is to be inspected while it is being driven, make sure that the SST harness does not interfere with parts in the engine room.

Terminal Voltage Table (reference value)

(Ignition switch is at ON, and connector is connected unless indicated otherwise)

Terminal

Signal

Connected to

Test condition

Voltage (V)

Action

A
B
RR wheel-speed
RR wheel-speed sensor
Vehicle is stopped
0 (AC)
• Inspect harness (wheel-speed sensor - ABS HU/CM).
• Inspect wheel-speed sensor.
• Inspect related harness.
Inspect using the wave profile.
C
F
LR wheel-speed
LR wheel-speed sensor
Vehicle is stopped
0 (AC)
Inspect using the wave profile.
D
G
RF wheel-speed
RF wheel-speed sensor
Vehicle is stopped
0 (AC)
Inspect using the wave profile.
E
I
LF wheel-speed
LF wheel-speed sensor
Vehicle is stopped
0 (AC)
Inspect using the wave profile.
Q
Vehicle speed output
Instrument cluster
Vehicle is stopped.
0
• Inspect harness (ABS HU/CM - Instrument cluster).
• Instrument cluster.
• Inspect front wheel- speed sensor.
• Inspect related harness.
Inspect using the wave profile.
T
OBD
KLN terminal of DLC
It cannot be determined with terminal voltage whether the condition is good or bad because advanced function diagnostic output is performed with serial communication. Inspect with service codes.
• Inspect harness, fuse (battery - ABS HU/CM-KLN terminal).
• Inspect related harness.
U*1
-
DLC-2
-
No need to check
-
V
OBD
TBS terminal of DLC-2
-
10-14
• Inspect harness (battery-ABS HU/CM-TBS terminal).
• Inspect related harness.
W
ABS warning light
ABS warning light
Illuminated
1.5 min.
• Inspect harness, fuse (battery-ABS warning light - ABS HU/CM).
• Inspect related harness.
Not illuminated
0.5 max.
X
Brake system warning light
Brake system warning light
Illuminated
1.5 min.
• Inspect harness, fuse (battery-Brake system warning light - ABS HU/CM).
• Inspect related harness.
Not illuminated
0.5 max.
Y
Brake switch
Brake switch
Brake pedal is depressed
B+
• Inspect harness, fuse (battery-brake switch-ABS HU/CM).
• Inspect related harness.
Brake pedal is released
0.5 max.
Z
Battery
Ignition switch
-
B+
• Inspect harness, fuse (battery-IG SW-ABS HU/CM).
• Inspect related harness.
AA, AD
Ground
Ground
-
Below 1.0
• Inspect harness (ABS HU/CM-ground point).
• Inspect related harness.
AB
Battery (ABS motor)
Battery
-
B+
• Inspect harness, fuse (battery-ABS HU/CM).
• Inspect related harness.
AC
Battery (Solenoid valve)
Battery
-
B+

*1 :
Used for vehicle manufacturing, not used for ABS.

Inspection Using An Oscilloscope (Reference)

Wheel speed

• ABS HU/CM terminal:
RF: G (+) - D (-)
RR: A (+) - B (-)
LF: I (+) - E (-)
LR: C (+) - F (-)

• Oscilloscope setting: 1 V/DIV (Y), 2 ms/DIV (X)
• Vehicle condition: Driving 30 km/h [18.6 mph]
Note
• As vehicle speed increases, period of wave shortens.
• If malfunctioning in the sensor rotor, wave profile will warp.

Vehicle speed output

• ABS HU/CM terminal: Q (+) - AA (-)

• Oscilloscope setting: 2 V/DIV (Y), 25 ms/DIV (X)
• Vehicle condition: Driving 25 km/h [15.5 mph]
Note
• As vehicle speed increases, period of wave will shortens.