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

No retarder operation

Driving in reverse gear not possible or limited.

No ANS-function

Driving in 1st gear only. Higher gears at very high engine speed only (engine protection).

If a substitute function is available, the fault may cause hard shifts and hard retarder activation.

If the engine speed sensor is simultaneously defective, only limp-home mode is available.

Possible causes

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

Place of action

Transmission output speed detection (sensor voltage)

Transmission control unit

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