TTEC4848 Vehicle Electronic Controls- blog 4 ABS and C.A.N system

A B S 

Anti-lock Braking Systems (off-car)

first I read the wiring diagram and find the each components and wires colour and identify the ABS control unit and ABS motor, also identify the which solenoids control which wheel cylinder.

From this picture we can know four different condition of the inlet and outlet solenoids valves operation:

1.when the normal braking the inlet valve is open and the outlet valve will be closed

2.when the ABS is operating to reduce wheel brake pressure the inlet valve is closed and the outlet valve will be open

3.when the ABS is operating to hold brake pressure the inlet valve is closed and the outlet valve will be closed

4.when the ABS is operating to increase wheel brake pressure the inlet valve is open and the outlet valve will be closed

this photo show us the anti-lock braking system also it show us the wheel speed sensor, this sensor is magnetic sensor.
When we use the oscilloscope to test the sensor we read the voltage is AC voltage. The other photo show us when the wheel speed sensor works how does the oscilloscope show us the voltage waveform is. We measure AC volts with a multi-meter and record is:
Left front  3.2V
Left rear   4.09V
Right front 2.79V
Right rear  2.87V

Also we use the feeler gage to check the
gap size between the sensor and teeth of the wheel and we get if the different gap size would make the voltage different and dirt between the sensor and teeth of the wheel could made same different voltage.








Anti-lock Braking Systems (on-car)

We use the vehicle is MAZDA familia 998, first we checked all of safety solution and than we take the four wheels off and find the wheel speed sensor. Than we use feeler gage to checked all sensor's gap and follow the specification all of them in good condition.

We know the ABS is very important use for safety part of the vehicle and if any problem with the wheel speed sensor it may be told to the ECU wrong condition and the ECU will be made the wrong decided to the wheel.

C.A.N system

CAN system: Controlled Area Network

This board show us the CAN system between the ECU and the Control system, because the ECU control all of the vehicle electric system if it just control direct it may have lots of wires input and output the ECU, so the CAN system make this connection control easier.

This is control unit door

              ECU 

This board show us the H-CAN and L-CAN works, from the vehicle we know about the Low-CAN system of the vehicle is door locker/ windows/ lights e.g and the High-CAN system is vehicle speed sensor/ ABS/ ESP e.g









We use the oscilloscope to check the low-CAN and High-CAN voltage waveform, and we can see the yellow line is show us the high-CAN waveform and the blue line is the Low-CAN waveform.