Description

Implausible frequency

Effects on the driving operation

No retarder operation.

No switching into reverse gear.

No ANS-function.

Only change gears to protect the engine against under or over-speed.

For substitute functions, possibly hard shifts and hard retarder activation.

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

Main pressure to maximum.

Reduction of the engine torque to protect the transmission.

Possible causes

Implausible speed ratios between engine output speed and transmission output speed have been measured in the mechanical gear which are not possible due to the transmission ratio. Attention: The engine speed sensor can also be the cause of this fault!

Possible causes: The sensors are installed in the wrong position, defect of the speed sensors, no correct adhesion of the disks.

Place of action

Transmission mechanics

Engine speed sensor

Transmission output speed sensor

Instruction

Check all frequency transmitters for correct signal generation and correct installation (check the distance to the measurement gear).

Setting conditions of the event

No description available.

Testing 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 function.

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

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

These steps are necessary to ensure the entire vehicle functions correctly.