Description

Communication on the CAN bus is disturbed due to ´CAN warning´ conditions.

A ´CAN warning´ is caused by a CAN controller receiving too many invalid data.

A CAN controller in warning condition can still read data from the CAN bus but it can no longer send data.

The warning condition is automatically cancelled once the CAN controller has received a certain percentage of valid data.

Effects on the driving operation

Limited driving operation.

The transmission shifts to neutral.

Possible causes

This fault message is generated by the hardware and occurs when the control unit has problems sending.

The fault is caused by:

- Faulty terminating resistors on the CAN bus.

- Loose contact in the CAN lines.

- Too high contact resistances in the CAN cabling.

- Other control units are not ready to receive.

- Transmission control unit alone on the CAN bus.

Place of action

No description available.

Instruction

Measure resistance between CAN-H and CAN-L ( ~ 60 Ohm ). Check cabling.

- Install/repair terminating resistors on the CAN bus.

- Check CAN wiring and plug-in connectors for loose contact and contact resistances.

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.