Description

The safety computer cannot close the internal safety switch.

Effects on the driving operation

Driving is not possible.

Possible causes

Open plug connection at cable 1.

Defective plug connection at cable 1.

Conducting connection of the common solenoid valve ground to another cable

Conducting connection of the common solenoid valve ground to the transmission housing

Conducting connection of the common solenoid valve ground to the vehicle chassis

Interruption of the common solenoid valve ground

Hardware defect of the safety switch

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.

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

Pin assignment of transmission connector

Pin	Name	Pin	Name	Pin	Name
1	S-GND	14	RBK	27	EKM
2	MV-GND	15	RBG	28	PBM
3	MV-GND	16	TB	29	RBKM
4	---	17	WR	30	TBM
5	T-CONV	18	---	31	MVM-GND
6	T-SUMP	19	---	32	N1+
7	OIL-LVL	20	---	33	N1-
8	P-DIFF	21	TIM-	34	N2+
9	SK	22	TIM+	35	N2-
10	DK	23	---	36	N3+
11	EK	24	SHIELD	37	N3-
12	PB	25	SKM
13	WP	26	DKM

Place of action

No description available.

Instruction

Check plug connections at cable 1.

Should the fault not disappear, 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
		Aftersales service index