Function Description - Auto Hold

WARNING: This page does not describe the selected car, but rather 18 other vehicles, including the 2016 Audi S4, 2016 Audi A4 Quattro, 2016 Audi A4, 2015 Audi S4, and 2015 Audi A4 Quattro. However, it is still accessible from the selected car via links, so may be relevant.

Depending on the model, the vehicle may be equipped with Audi Hold Assist (AHA).

Function

The function assists the driver if the vehicle must remain stopped frequently or for long periods of time when the engine is running.

When the vehicle is stopped and the function is activated, the vehicle is held in place by Audi Hold Assist (AHA).

The driver can release the brake pedal.

The vehicle is held in place by maintaining the brake pressure on all four wheels in ESP.

To prevent the ESP solenoid valves to overheat when stopped for long periods of time, the rear Electromechanical parking brake automatically takes over braking when the solenoid valves reach a temperature of 200 °C.

The point when the brakes automatically release is based on the following information:

Engine speed
Angle
Gear engaged
with manual transmissions, distance on the clutch pedal through the clutch sensor
with automatic transmissions, through converter release

To prevent the vehicle from rolling back, the brakes are only released when there is sufficient engine torque.

Activation

The following conditions must be fulfilled to switch the "stand by" function on:

Driver wearing seat belt
Engine running
Driver door closed
No ESP and electronic parking brake malfunctions.

The switch -2- in the center console activates the function.

Fig 1: Identifying Hold / Parking Brake Switches

Courtesy of AUDI OF AMERICA, LLC

The switch indicates the operating conditions.

Deactivated - the LED in the switch is off.
stand by - the LED in the switch is on.
Active - the LED in the switch is on and the instrument cluster display shows a green "P".

Braking function is only transferred from ESP to the electronic parking brake if the "green P" in the instrument cluster is visible and if:

the solenoid valves in ESP have reached a temperature of 200 °C
the driver door is opened
the driver seat belt is unlatched
the engine is stopped
the ignition is switched off
the switch is operated
the brake pedal or gas pedal are pressed.
the Audi Hold Assist switch is operated without pressing the brake.

NOTE:

When braking function is transferred from the ESP to the electronic parking brake, the instrument cluster display changes from a "green P" to a "red P".