EBS ”emergency modes” EBS test types As a rule, certain EBS functions are deactivated when an error is detected. Functions not impaired by the failure are maintained. For the EBS-drive with limited functions, the term emergency mode is used. The following peculiarities must be observed while testing the electronically controlled braking system: Maximum pressure level control: The following functions can be deactivated if an error occurs: When the brake is applied > 80% of the pedal distance and ignition off, the full pressure works on the front and rear axles. Operation without ABS function The ABS function can be deactivated on a wheel, an axle, or the entire vehicle. Possible causes:
faulty speed sensor signal, ABS valve error, etc. Roller dynanometer test: (Roller dynanometer function) A roller dynanometer function was integrated into the EBS electronic unit so that an electronically braked KOM can be tested on a roller dynanometer. This function is used to test the braking pressure at full load (permitted total weight). Operation without ASR function The traction control system can be switched off completely or partially. Complete deactivation means that both the braking system and the engine control unit are deactivated. Partial deactivation means that only the braking system is deactivated. Possible causes:
(faulty speed sensor signal, etc.) The roller dynanometer function is activated if the EBS is not switched on via the ignition (class 15) when the vehicle is braked again, but rather through activation of the brake signal transmitter via the integrated brake switches. The front axle and/or rear axle speed must be Pressure control / auxiliary pressure control Normally, braking pressure control requires braking pressure sensor signals. When these signals are no longer available, electrical braking pressure can be produced. In this case, we talk in terms of pressure control operation or auxiliary pressure control.
However, the accuracy of this pressure production is limited, compared to hitch-free pressure control. Possible causes: Pressure sensor signal failure, etc.) Special EBS controls such as endurance brake integration, delay control and brake lining wear control are not active when the roller dynanometer function is active. The maximum braking pressure can now be measured. The EBS is working correctly if the measured braking pressure corresponds to the basic loaded vehicle design. Redundancy operation If electrical pressure control becomes impossible, the corresponding axle is braked with the help of the pneumatic redundancy pressure. Possible causes:
damaged solenoid, or faulty solenoid cabling, etc.) WABCO Diagnosis equipment - see: brochure 820 001 029 3 Emergency modes/control possibilities 6. EBS 20