Electronic Power Assist Steering (EPAS)
Posted: Thu Aug 10, 2017 3:21 pm
I thought this was a very interesting read. Basically when your brakes are warped and stuffed and need replacing you probably won't even know.
Electronic Power Assist Steering (EPAS)
The EPAS system provides steering assist to the driver using steering gear equipped with an integrated electrical motor. The EPAS system electric motor is fitted to and directly drives the steering rack.
The EPAS provides maximum assistance when parking and at low vehicle speeds, and reduced power assistance at higher vehicle speeds where less effort is needed. EPAS offers significant improvements in fuel economy compared to electro-hydraulic and hydraulic power-assisted steering systems.
The EPAS system continuously corrects the vehicle steering to compensate for road irregularities, improving overall steering feel. It continually learns and compensates for changes in the road surface which can cause the vehicle to pull left or right. The EPAS system incorporates the following integrated features:
Torque Steer Compensation
Torque steer compensation is used to reduce the steering pull to one side, which is often experienced during heavy acceleration. The EPAS subtly provides a counter steering force to eliminate torque steer and keep the vehicle on its intended path. This reduces effort required by the driver to correct the steering pull experienced during torque steer.
Active Nibble Compensation
The EPAS active nibble compensation feature compensates for any vibration that can be felt through the steering at high speeds. Nibble is often caused by an out of balance front wheel or brake shudder. The EPAS electric motor provides a counter steering force to cancel out this steering wheel vibration.
EPAS Failure Modes
When a DTC (diagnostic trouble code) is present in the PSCM (power steering control module), the EPAS enters 1 of 2 modes of operation.
The EPAS enters a reduced steering assist mode to protect the internal components of the EPAS when a concern is detected by the PSCM such as low/high battery voltage or over-temperature concerns that are not considered to be a critical safety concern. This reduced steering assist mode gives the steering a heavier than normal feel.
The EPAS enters a manual steering mode (no electrical steering assistance is provided) when a concern that is considered to be a critical safety concern is detected. In manual steering mode, the vehicle has mechanical steering operation only, which gives steering operation a heavy feel.
Electronic Power Assist Steering (EPAS)
The EPAS system provides steering assist to the driver using steering gear equipped with an integrated electrical motor. The EPAS system electric motor is fitted to and directly drives the steering rack.
The EPAS provides maximum assistance when parking and at low vehicle speeds, and reduced power assistance at higher vehicle speeds where less effort is needed. EPAS offers significant improvements in fuel economy compared to electro-hydraulic and hydraulic power-assisted steering systems.
The EPAS system continuously corrects the vehicle steering to compensate for road irregularities, improving overall steering feel. It continually learns and compensates for changes in the road surface which can cause the vehicle to pull left or right. The EPAS system incorporates the following integrated features:
- Torque steer compensation
- Active nibble compensation
Torque Steer Compensation
Torque steer compensation is used to reduce the steering pull to one side, which is often experienced during heavy acceleration. The EPAS subtly provides a counter steering force to eliminate torque steer and keep the vehicle on its intended path. This reduces effort required by the driver to correct the steering pull experienced during torque steer.
Active Nibble Compensation
The EPAS active nibble compensation feature compensates for any vibration that can be felt through the steering at high speeds. Nibble is often caused by an out of balance front wheel or brake shudder. The EPAS electric motor provides a counter steering force to cancel out this steering wheel vibration.
EPAS Failure Modes
When a DTC (diagnostic trouble code) is present in the PSCM (power steering control module), the EPAS enters 1 of 2 modes of operation.
The EPAS enters a reduced steering assist mode to protect the internal components of the EPAS when a concern is detected by the PSCM such as low/high battery voltage or over-temperature concerns that are not considered to be a critical safety concern. This reduced steering assist mode gives the steering a heavier than normal feel.
The EPAS enters a manual steering mode (no electrical steering assistance is provided) when a concern that is considered to be a critical safety concern is detected. In manual steering mode, the vehicle has mechanical steering operation only, which gives steering operation a heavy feel.