125000475 - C12 THE GEARS DO NOT ENGAGE

Reverse gear cannot be engaged sometimes
Results of the tests
0OIL LEVEL CHECKAll OKProblems metOperation
Check the oil level as described in See Test    See Test 2127B OIL LEVEL CHECKContinue to Step 2Level below the Max referenceTop up the oil levelContinue to Step 1
Level above the Max referenceReduce to the Max levelContinue to Step 2
1CHECK FOR OIL LEAKSAll OKProblems metOperation
Check that there are no oil leaks as described in See Test    See Test 2127C HYDRAULIC GEAR SELECTION SYSTEMContinue to Step 2Oil leaks detected in the clutch assemblyCarry out the clutch bleeding procedure in active diagnosis using the ExaminerContinue to Step 2
Oil leaks detected in other parts of the hydraulic unitReplace/repair the parts concerned, and top up the oil levelContinue to Step 1
2OIL PRESSURE CHECKAll OKProblems metOperation
Check the amount of oil present and continue with the topping upCheck the oil pressure as described in See Test    See Test 2127D OIL PRESSURE CHECKContinue to Step 4Pressure < 40 barContinue to Step 3
3ELECTRIC PUMP OPERATION CHECKAll OKProblems metOperation
Check the correct operation of the pump as described in See Test    See Test 2127E ELECTRIC SPEED SELECTION SYSTEMContinue to Step 4Voltage below 11 VCheck the batteryContinue to Step 3
It is not possible to make gear changes from the leverActivate the ''clutch bleed'' service from the Examiner Plus or Smart to activate the pumpContinue to Step 4
4GEAR LEVER CHECKAll OKProblems metOperation
Check that the gear lever is working properly following See Test    See Test 2127L GEAR LEVER CHECKContinue to Step 5The lever states displayed are not correctCheck the wiring and the switches/gear lever Repair/replace the part that is not working
There is no change of state and/or the ''CITY'' button is not displayedCheck the switch and the wiring Repair/replace the part that is not working
5CONTROL UNIT ERRORS CHECKAll OKProblems metOperation

Check that there are no control unit errors. In particular:

  • Clutch sensor error
  • Lever switches error 0/1/2/3
  • Even gear engagement error
  • Odd gear engagement error
  • Clutch solenoid current error
  • 5th/Reverse selection solenoid valve error
  • Control unit earth error
  • Load relay error
Continue to Step 10Presence of one or more of the errors included in the listContinue to Step 6
6CHECKS ON FAULTS DETECTEDAll OKProblems metOperation
Check the faults according to See Test    See Test 2127I What to do for error in Selespeed control unitContinue to Step 8Faulty connections (Clutch sensor, Odd or even gear engagement, Clutch solenoid Current error, Selection solenoid valve error, Control unit earth error and/or Load relay error)Repair/replace the wiringContinue to Step 8
The state displayed is not correct (lever switch error 0/1/2/3)Check the connections, continuity of the wiring and the gear leverContinue to Step 8
The active diagnosis has not been successful and there are no faults detected at the wiring (Odd or even gear engagement, Selection solenoid valve error and/or Clutch solenoid valve current error)Continue to Step 7
Battery run down (Load relay error)Restore the correct battery charge Op. 5530C14Continue to Step 6
7AFTER THE SOLENOID VALVE ACTIVE DIAGNOSISAll OKProblems metOperation
If this step has been reached for the active diganosis of the clutch solenoid valve, replace it Op. 2127C56and check its operation by carrying out a C.M.If this step has been reached for the active diagnosis of the selection solenoid valve, replace it Op. 2127C54and check its operationIf this step has been reached for the active diagnosis of the engagement solenoid valve, replace it Op. 2127C52and check its operationContinue to Step 8.
8POTENTIOMETER REPLACEMENTAll OKProblems metOperation
If there is a clutch sensor error and no faults are detected at the connections/wiring, replace the clutch potentiometer Op. 2127E44and check that the position reading is correct by carrying out a series of C.M.Continue to Step 9.
9AFTER THE CHECKS ON THE FAULTS DETECTEDAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisThe fault persistsContinue to Step 10
10CHECK THAT THE CLUTCH IS NOT DRAGGINGAll OKProblems metOperation
Check that the clutch is not dragging following See Test    See Test 2127K CLUTCH DRIVE CHECKEnd of diagnosisThe clutch dragsReplace the clutch mechanism Op. 1810A28Continue to Step 11
11AFTER OPERATION ON CLUTCH KITAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisThe fault persistsContact Technical Service for further information on the problem