Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Abs (Anti-Lock Brake System): Description: Operation
The HECU shall be put into operation by switching on the operating voltage (IGN).
On completion of the initialization phase, the HECU shall be ready for operation.
In the operating condition, the HECU shall be ready, within the specified limits (voltage and temperature), to process the signals offered by the various sensors and switches in accordance with the control algorithm defined by the software and to control the hydraulic and electrical actuators. The HECU shall receive wheel speed signal from the four inductive wheel sensors.
The wheel signals are converted to square wave by the signal conditioning circuit and given as input to the micro-processor.
The sensor connections shall be monitored for short-circuit and interruption and then in the event of 2 sensor failures, the HECU shall shut down the system.
When one side of the valve coil is connected to the positive voltage that is provided through the valve relay and the other side is connected to the ground by the MOSFET, the solenoid valve goes into operation.
The electrical function of the valves are always monitored by the valve test pulse under normal operation conditions. When overvoltage is detected (above 16V), the HECU switches off the valve relay and shuts down the system. When voltage is returned to operating range, the system goes back to the normal condition after the initialization phase.
In the event of undervoltage (below 10V), ABS control shall be inhibited and the warning lamp shall be turned on.
When voltage is returned to operating range, the warning lamp is switched off and the HECU returns to normal operating mode.
The pump motor operates when the ABS is functioning. The HECU performs a pump motor test at a speed of 20 km/h once after turned the Ignition switch on. You may hear the motor operate at this time, but it is normal. Malfunctions or failures detected by the HECU are encoded on the HECU, stored in a EEPROM and read out by diagnostic equipment (hi-scan pro) when the ignition switch is turned on.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.