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

The transmission function is limited due to sporadic unavailability of various functions such as engine torque reduction, retarder function, vehicle does not drive or only with restrictions.

Possible causes

This error 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 CAN1 bus.

* Loose contact.

* Too high contact resistances in the CAN1 cabling.

* Other control units are not ready to receive.

* Transmission control unit alone on the CAN1 bus.

Connector pin assignment of transmission control unit

Pin	Stecker A	Stecker B	Stecker C	Stecker D
1	SHIELD	EK	FLEXI-1	-BATT
2	TIM+	DK	---	IGN
3	TIM-	SK	FLEXI-3	FLEXI-11
4	N1+	RBK	FLEXI-4	K-LINE
5	N1-	TB	FLEXI-5	CAN1-H
6	N2+	---	FLEXI-6	CAN1-H
7	N2-	RBG	FLEXI-7	CAN-SHLD
8	N3+	PB	FLEXI-8	CAN1-L
9	N3-	WR	FLEXI-9	CAN1-L
10	---	WP	FLEXI-10	CAN2-H
11	---	---	FLEXO-2H	CAN2-H
12	EKM	FLEXI-12	FLEXO-4H	CAN2-L
13	DKM	S-GND	FLEXO-3H	CAN2-L
14	SKM	OIL-LVL	FLEXO-5L	CAN1-R
15	PBM	T-SUMP	---	---
16	TBM	---	---	FLEXO-1L
17	RBKM	T-CONV	---	CAN2-R
18	MVM-GND	MV-GND	---	+BATT

Place of action

CAN bus

Troubleshooting

Measure resistance between CAN1-H and CAN1-L ( ~ 60 Ohm ). Check cabling.

* Install/repair terminating resistors on the CAN1 bus.

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

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