Description

The CAN controller has detected a warning status on the CAN bus. A CAN warning status is caused by a CAN controller receiving too many invalid data. In the warning status, the CAN controller can only receive data.

Effects on the driving operation

Driving is not possible or restricted.

Possible causes

Line interruption at the CAN bus.

Short-circuit between CAN-H and CAN-L

Short-circuit to ground of a CAN line.

A bus node is sending with an incorrect baud rate.

A bus node is defective.

The CAN transceiver in the control unit is defective.

Strong electromagnetic radiation.

Function of the safety computer

The safety computer (S-CPU) monitors safety-relevant signals which the function computer (F-CPU) sends or receives. If the safety computer detects an inadmissible condition, it initiates a reset of the function computer. During that time, the transmission system is in a safe mode (neutral).

Driving operation is only released if both the function computer AND the safety computer give their approval simultaneously. After the release the safety switch in the transmission control unit is closed and the ground of the solenoid valves is connected to the battery ground. Only then can the solenoid valves be activated and enable driving operation.

Place of action

No description available.

Troubleshooting

Check terminating resistors. Check CAN bus including all bus nodes.

If the fault cannot be eliminated, please contact the VOITH customer service.

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:

		Troubleshooting a short-circuit to ground
		CAN 2 - Hardware Occurrence of a bus-warning state
		Aftersales service index