Scan Tool Testing and Procedures

Description of parameters

POWER SUPPLY
Measurement range 0-20.4 V.
Indicates the present voltage of the 30-supply to the electrical power steering module (EPS).

BATTERY VOLTAGE, (CEM)
Measurement range 0-30 V.
Indicates the present battery voltage from the central electronic module (CEM). The electrical power steering module (EPS) receives the battery voltage signal via the CAN network.

POWER CONSUMPTION PUMP MOTOR
Measurement range 0-255 A.
Indicates the present power consumption of the pump motor. The power consumption is measured indirectly at the output for the power stage for the electrical power steering module (EPS). The power consumption can vary considerably depending on the present operating situation.

Hint: The normal value with the engine running and no steering taking place is approximately 6-8 A. In extremely cold conditions, the power consumption can be significantly higher. If steering is being performed, the power consumption will rise considerably. A diagnostic trouble code (DTC) for too high a current will be stored if the power consumption exceeds 96 A.

PUMP MOTOR SPEED, ACTUAL VALUE
Measurement range 0-6375 rpm.
Indicates the present speed of the pump motor. The speed is measured via an engine speed sensor that is integrated in the pump motor for the electrical power steering module (EPS). When the engine is running, the car is stationary and no steering wheel movements are taking place, the speed of the pump motor must be approximately 2900 rpm +/- 100 rpm, depending on the vehicle profile.

Hint: The speed must correspond to the parameter "Pump motor speed desired value". A difference of approximately 30 rpm between the Actual value and the Desired value is normal. In extremely cold conditions, significantly greater differences can arise between the Actual and the Desired values.

PUMP MOTOR SPEED, DESIRED VALUE
Measurement range 0-6375 rpm.
Indicates the pump motor speed requested by the electrical power steering module (EPS). The requested pump motor speed is, indirectly, the regulation of the servo assistance which the electrical power steering module (EPS) considers to be optimal for the present operating situation. When the engine is running, the car is stationary and no steering wheel movements are taking place, the speed of the pump motor must be approximately 2900 rpm +/- 100 rpm, depending on the vehicle profile.

Hint: The speed must correspond to the parameter "Pump motor speed Actual value". A difference of approximately 30 rpm between the Actual value and the Desired value is normal. In extremely cold conditions, significantly greater differences can arise between the Actual and the Desired values.

STEERING WHEEL MOVEMENT SPEED
Measurement range 0-1530° / s.
Indicates the present speed of steering wheel movement. The electrical power steering module (EPS) receives the steering wheel movement signal via the CAN network from the steering wheel module (SWM). The steering wheel module (SWM) registers the number of degrees/seconds by which the steering wheel angle is altered during a steering wheel movement.

Hint: When the engine is running and no steering wheel movement is taking place, the value must be 0° / s. A rapid steering wheel movement should produce a high value, while a slower steering wheel movement should produced a low value.

TEMPERATURE IN THE CONTROL MODULE
Measurement range -40- +215 °C.
Indicates the present temperature registered by the internal thermistor in the electrical power steering module (EPS).

Hint: A diagnostic trouble code (DTC) will be stored if the temperature exceeds 110 °C. A diagnostic trouble code (DTC) can also be stored in the event of a high outside temperature or engine compartment temperature combined with "hard driving".

TEMPERATURE IN POWER STAGE
Measurement range -40- +215 °C.
Indicates the internally calculated temperature of the power stage in the electrical power steering module (EPS).

Hint: A diagnostic trouble code (DTC) will be stored if the temperature exceeds 175 °C. A diagnostic trouble code (DTC) can also be stored in the event of a high outside temperature or engine compartment temperature combined with "hard driving".

VEHICLE SPEED
Measurement range 0-255 km/h.
Displays present vehicle speed. The electrical power steering module (EPS) receives the speed signal via the CAN network from the brake control module (BCM).

ENGINE RUNNING
Indicates whether the engine is running or not. The electrical power steering module (EPS) receives the engine status signal via the CAN network from the engine control module (ECM). This signal uses the electrical power steering module (EPS) to start the pump motor (the power steering function). The pump motor normally only runs when the engine is running.
YES = Engine running.
NO = Engine not running.

Hint: If the engine status signal from the engine control module (ECM) is incorrect or absent for any reason, the engine speed (RPM) signal from the engine control module (ECM) will be used by the electrical power steering module (EPS). If the engine speed (RPM) signal is also absent, the pump motor will start directly after ignition on.

POWER STEERING EFFECT
Indicates if the electrical power steering module (EPS) has activated the power steering function or not.
YES = Power steering function is activated.
NO = Power steering function is not activated.

SPEED SENSITIVE POWER STEERING EFFECT
Indicates if the electrical power steering module (EPS) can regulate the power steering effect based on vehicle speed or not.
YES = The speed sensitive power steering effect is working.
NO = The speed sensitive power steering effect is not working.

Hint: If the vehicle speed signal from the brake control module (BCM) is absent or incorrect, the speed sensitive power steering effect will not work.

REQUEST WARNING LAMP/TEXT
Indicates whether the electrical power steering module (EPS) requests that the warning lamp and text message to the driver are lit or not. The request to light the warning lamp and the text message is sent on the CAN network from the electrical power steering module (EPS) to the central electronic module (CEM). The request is then forwarded to the driver information module (DIM) where the warning lamp and the text message are lit.
ON = Lighting the lamp and present text message are requested via the CAN network.
OFF = Lighting the lamp and present text message are NOT requested via the CAN network.