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Functional check of freewheel lock
Functional check of freewheel lock
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● A 2nd mechanic is required when checking the freewheel lock.
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‒ Raise vehicle.
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‒ To build up a vacuum for the positioning element start engine and run for approx. 30 seconds.
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‒ Engage reverse gear.
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‒ Switch off ignition.
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‒ Switch on ignition.
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‒ Rotate rear wheels forwards and backwards.
The propshaft must drive the front wheels when rotating in both directions.
When rotating forwards the freewheel lock must be heard to engage immediately.
The following may be at fault if the rear wheels rotate forwards without resistance:
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◆ Pneumatic system
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‒ Pipes, hoses and connections
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‒ Non-return valve and vacuum reservoir (in engine compartment)
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‒ Check for leaks using hand pump V.A.G 1390.
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‒ Positioning element diaphragm
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◆ Electrical system
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‒ Check wiring and components for short or open circuit according to current flow diagram.
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‒ Check solenoid in positioning element (must be heard to engage when switching on ignition).
If the pneumatic and electrical systems are OK then the free-wheel unit or the free wheel unit mechanical lock is defective.To service dismantle rear final drive .
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