Description

Thesafety computer detects an inadmissible solenoid valve condition with the gear range selector set to reverse. This condition is characterised by the solenoid valve condition TB activated and the gear range selector set to reverse. This condition may lead to the propulsion of the vehicle.

Effects on the driving operation

Driving operation is blocked for safety reasons. The transmission assumes a safe state.

Possible causes

Faulty solenoid valve wiring.

Defective solenoid valve.

Potential shift due to an inadmissibly high line resistance of the ground cable.

Faulty information on driving direction.

Faulty activation of solenoid valve by the function computer.

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.

Instruction

Check plug connections, cabling and solenoid coil.

Should the fault not disappear, please contact the VOITH customer service.

Evaluation of SV states

Above a voltage of 5 V the solenoid coils activate the hydraulic valves. The safety computer recognises the condition "activated" already above a voltage of 2.9 V. This ensures that safety-crucial conditions of solenoid valves are detected before they can cause misshifts in the transmission.

Setting conditions of the event

- Gear range selector set to reverse

-Voltage TB (min. 0.3s)> 5V

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:

		TB solenoid valve Short-circuit to supply voltage in the operating coil's electric circuit
		Aftersales service index