GF42.25-W-2009D | Hill holder, function | 25.10.06 |
MODEL 970, 972, 974, 975, 976
with CODE (BB1) Brake control (BS)
with CODE (ZX2) EPB II
MODEL 970, 972, 974, 975, 976
with CODE (BB8) Brake control (BS) with ASR
with CODE (ZX2) EPB II
General information
The hill holder prevents the vehicle from rolling backwards or forwards unintentionally.
It is a function integrated in the brake system (BS) control unit (A110a1) and helps the driver to keep his vehicle steady while stationary and when moving off, particularly on gradients, without having to apply the parking brake.
Function
The hill holder is switched to standby with the hill holder switch (S41). The hill holder indicator lamp (P2h11) in the Instrument (INS) (P2) lights up to notify the driver.
A brake application with the service brake activates the hill holder. The brake pressure applied while the vehicle is stationary is maintained for as long as the presence of the driver is detected.
The presence of the driver is detected by the driver depressing (even slightly) at least one of the pedals (clutch pedal, brake pedal or accelerator pedal).
The hill holder is deactivated as the drive torque builds up and clutch travel is detected when the vehicle moves off, or before this if all the pedals are released and the presence of the driver is no longer detected (in this case a short warning tone sounds before the brakes are released).
In vehicles with code (GE2) Electronic drive control II, only the operation of the brake pedal has an effect on the function of the hill holder.