125000483 - C21 THE GEARBOX IS STUCK

It remains stuck in one gear and, when the vehicle stops, the engine cuts out and cannot be started up again or it starts again after a few minutes. Preliminary check: If during engine starting you notice that the starter motor works normally, the problem is caused by other systems (engine management, ABS, fuel pump). Refer to specific charts. If the starter motor does not turn (after checking its operation and the relevant electrical supply circuit), continue with the next diagnosis chart.

		Results of the tests
0	OIL LEVEL CHECK	All OK	Problems met	Operation
	Check the oil level as described in See Test    See Test 2127B OIL LEVEL CHECK	Continue to Step 2	Level below the Max reference	Top up the oil levelContinue to Step 1
			Level above the Max reference	Reduce to the Max levelContinue to Step 2
1	CHECK FOR OIL LEAKS	All OK	Problems met	Operation
	Check that there are no oil leaks as described in See Test    See Test 2127C HYDRAULIC GEAR SELECTION SYSTEM	Continue to Step 2	OIl leaks detected	Replace/repair the parts concerned, and top up the oil levelContinue to Step 1
2	OIL PRESSURE CHECK	All OK	Problems met	Operation
	Check the oil pressure as described in See Test    See Test 2127D OIL PRESSURE CHECK	Continue to Step 4	Pressure < 40 bar	Continue to Step 3
3	ELECTRIC PUMP OPERATION CHECK	All OK	Problems met	Operation
	Check the correct operation of the pump as described in See Test    See Test 2127E ELECTRIC SPEED SELECTION SYSTEM	Continue to Step 4	Voltage below 11 V	Check the batteryContinue to Step 3
			It is not possible to make gear changes from the lever	Activate the ''clutch bleed'' service from the Examiner Plus or Smart to activate the pumpContinue to Step 4
4	CONTROL UNIT ERRORS CHECK	All OK	Problems met	Operation
	Check that there are no control unit errors. In particular: Clutch sensor error Clutch solenoid current error Pump relay error Load relay error	Continue to Step 9	Presence of one or more of the errors included in the list	Continue to Step 5
5	CHECKS ON FAULTS DETECTED	All OK	Problems met	Operation
	Check the faults in accordance with See Test    See Test 2127I What to do for error in Selespeed control unit	Continue to Step 7	Faulty connections	Repair/replace the wiringContinue to Step 7
			The active diagnosis is not successful and no faults are detected at the wiring (Clutch solenoid valve current)	Continue to Step 6
6	AFTER THE SOLENOID VALVE ACTIVE DIAGNOSIS	All OK	Problems met	Operation
	If this step has been reached for the active diagnosis of the clutch solenoid valve, replace it Op. 2127C56and check the operation by carrying out a C.M.	Continue to Step 7	.
7	POTENTIOMETER REPLACEMENT	All OK	Problems met	Operation
	If there is a clutch sensor error and no faults are detected at the connections/wiring, replace the clutch position sensor Op. 2127E44and check the correct reading of the position by carrying out a series of C.M.	Continue to Step 8	.
8	AFTER THE CHECKS ON THE FAULTS DETECTED	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	The fault persists	Continue to Step 9
9	CLUTCH PUSH ROD ADJUSTMENT CHECK	All OK	Problems met	Operation
	Carry out the clutch push rod check as described in See Test    See Test 2127M CLUTCH PUSH ROD ADJUSTMENT CHECK	Continue to Step 10	The position is outside the permitted range	Restore the correct position Tighten to torque
10	AFTER THE CLUTCH PUSH ROD ADJUSTMENT	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	The fault persists	Contact Technical Service for further information on the problem