125000478 - C15 THE GEARS DO NOT ENGAGE IN AUTO" OPERATION

The gearbox remains stuck in one gear Whilst stationary the vehicle changes down to first gear and then no other gear can be engaged
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 detectedReplace/repair the parts concerned, and top up the oil levelContinue to Step 1
2OIL PRESSURE CHECKAll OKProblems metOperation
Check 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
4CONTROL UNIT ERRORS CHECKAll OKProblems metOperation

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

  • Brake switch error
  • Clutch sensor error
  • Even gear engagement error
  • Odd gear engagement error
  • Clutch solenoid current error
  • 1st/2nd selection solenoid valve error
  • 5th/Reverse selection solenoid valve error
  • Control unit earth error
  • Load relay error
Pump relay error
If there is a brake switch error, the recovery considers the brake to be constantly pressed with the engine running; this means that only changes to lower gears can take place in automatic mode
Continue to Step 7Presence of one or more of the errors included in the listContinue to Step 5
5CHECKS ON FAULTS DETECTEDAll OKProblems metOperation
Check the faults in accordance with See Test    See Test 2127I What to do for error in Selespeed control unitContinue to Step 7Faults detected (brake switch)Restore/replace the component/wiringContinue to Step 7
Faulty connections (Clutch sensor, Odd or even gear engagement, Clutch solenoid Current error, Selection solenoid valve error, Load relay error and/or Pump relay error)Repair/replace the wiringContinue to Step 7
The active diagnosis for the solenoid valve is not successful and no faults are detected at the wiring (Odd or even gear engagement, Clutch solenoid valve current error and/or Selection solenoid valve error)Continue to Step 6
Battery run down (Load relay error)Restore the correct battery charge Op. 5530C14Continue to Step 5
6AFTER THE SOLENOID VALVE ACTIVE DIAGNOSISAll OKProblems metOperation
If this step has been reached for the active diagnosis 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 engagement solenoid valve, replace it Op. 2127C52and check its operationIf this step has been reached for the active diagnosis of the selection solenoid valve, replace it Op. 2127C54and check its operationContinue to Step 7.
7POTENTIOMETER 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 8.
8AFTER THE CHECKS ON THE FAULTS DETECTEDAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisThe fault persistsContinue to Step 9
9CHECK ON BRAKE PEDAL SWITCHAll OKProblems metOperation
Check that the brake pedal switch is working properly in accordance with See Test    See Test 2127F CHECK ON BRAKE PEDAL SWITCHEnd of diagnosisThe brake pedal switch is not working properlyCheck the switch on the brake pedal, its fastening, its positioning, the wiring and the engine management control unit. Repair/replace the part that is not working Move on to Step 10
10AFTER THE BRAKE PEDAL SWITCH CHECKAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisThe fault persistsContinue to Step 11
11CHECK THE CLUTCH DISC SPEED SENSORAll OKProblems metOperation
Check the clutch disc speed signal in accordance with See Test    See Test 2127A HYDRAULIC TRANSMISSION EXTERNAL LINKAGEContinue to Step 14There are problems with the sensor signalContinue to Step 12
12CHECK THE STATE OF THE CONNECTIONSAll OKProblems metOperation
Check the state of connections and wiring of the speed sensor.
Remember that this sensor is on the gearbox bellhousing near the reversing lights sensor
Continue to Step 13There are faults detectedRepair/replace the part that is not workingContinue to Step 14
13REPLACE THE CLUTCH DISC SPEED SENSORAll OKProblems metOperation
Replace the clutch disc speed sensor Op. 2127E52Continue to Step 14.
14AFTER THE CHECK ON THE CLUTCH DISC SPEED SENSORAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisThe fault persistsContact Technical Service for further information on the problem