Description

Sensor voltage too low

If the sensor voltage drops below 4.5 V, the speed sensor signal can not be evaluated anymore.

Effects on the driving operation

Hard shifts

Driving in reverse gear is not possible or restricted.

If the output sensor is also defective, only limp-home mode available

No torque limitation relative to the engine speed

Engine torque reduction is limited.

The characteristic curve of the auxiliaries is not considered.

The engine speed and values derived from it are incorrectly set in the CAN communication.

Possible causes

Defect of the sensor, low-resistance connection between the two sensor terminals or defect of the transmission control unit

Place of action

Engine speed detection (sensor voltage)

Instruction

Measure voltage at the speed sensor.

Check plug connections, cabling and sensor.

Setting conditions of the event

No description available.

Test conditions of the event

No description available.

Final function check

If the defective component cannot be clearly identified, you should try to reproduce the fault:

• Reinstall the component in the vehicle.
• Test the function.

After the fault has been eliminated, the following steps have to be carried out:

• Conduct a test drive with function check.
• Read out the fault memory.
• Check the transmission for leaks.
• Perform a final visual inspection.

These steps are necessary to ensure the entire vehicle functions.

See also:

		Aftersales service index