Description

Sensor voltage too high

If the sensor voltage exceeds 14 V, the speed sensor signal cannot be evaluated anymore.

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

Low-resistance connection of the positive sensor terminal to supply voltage or defect of the transmission control unit

Place of action

Transmission output speed sensor

(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.

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.