Page 17 of 162
AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 17V3 MR-372-J84-23A000$225.mif
AJ0 BVA
Vdiag No.: 04, 05
"CONVERTER lock-up" FUNCTION:
Aim of this function: The aim of this function is to lock up the converter.
–lock-up/release definition:
The converter is a hydraulic clutch which provides a hydraulic connection between the engine and the automatic
transmission pressure plate.
The purpose of the lock-up function is to lock the turbine and the converter casing together, transforming a hydraulic
connection into a mechanical connection. The role of the lock-up function is to prevent slipping losses.
EVS2*: sequence solenoid valve 2."Lever selection"
function
"Converter
lock-up"
functionLock-up and brake 1
solenoid valve
Solenoid valve EVS2*
Oil temperature
Vehicle speed
Turbine speed
Brake pedal action
"Torque management"
function
–Accelerator pedal
position
–Engine speed
–Engine torqueCAN
"Gear change" function
Page 18 of 162
AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 18V3 MR-372-J84-23A000$225.mif
AJ0 BVA
Vdiag No.: 04, 05
"TORQUE MANAGEMENT" FUNCTION:
Purpose of this function:
The purpose of this function is to manage the torque setpoints during certain gear shifts by informing the injection
computer. This function means smoother gear shifts and better mechanical protection.
–Accelerator pedal
position
–Engine speed
–Engine torqueCAN
"Torque
management"
function Vehicle speed
CAN–Torque request
–Torque converter status
–Gear changes
(in progress)
Turbine speed
"Gear change" function
Page 19 of 162
AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 19V3 MR-372-J84-23A000$225.mif
AJ0 BVA
Vdiag No.: 04, 05
"SHIFT LOCK" FUNCTION:
Purpose of this function:
Shift-lock: locking the gear lever in position "P" and blocking the transmission to immobilise the vehicle while
stationary.
To release the gear lever from position "P", the vehicle must be stationary and the brake pedal depressed.
"Lever selection"
function
"Shift-lock"
function"Shift-lock" solenoid
Vehicle speed"Instrument panel
display" function
Turbine speed
+ After ignition feed
Page 20 of 162
AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 20V3 MR-372-J84-23A000$225.mif
AJ0 BVA
Vdiag No.: 04, 05
"INSTRUMENT PANEL DISPLAY" FUNCTION:
Purpose of this function:
The purpose of this function is to manage the transmission of multiplex line signals required for the instrument panel
display.
"Lever selection"
function
"Instrument
panel display"
functionCAN–Fault warning light
–"Shift-lock" warning
light
"Fault finding" function
"Shift-lock" function "EOBD",function
Brake pedal action
Page 21 of 162

AUTOMATIC TRANSMISSION
Fault finding - Replacement of components
23A
23A-21V3 MR-372-J84-23A000$270.mif
AJ0 BVA
Vdiag No.: 04, 05AUTOMATIC TRANSMISSION
Fault finding - Replacement of components
*sig.: signal
*EVS1 = shift solenoid valve 1
*EVS2 = shift solenoid valve 2
*LS = line pressure regulation solenoid valveTool fault Diagnostic tool title Defect modes
DF023Transmission oil temperature sensor
circuit–in the event of open circuit or short circuit+:
If the fault occurs while driving, the
transmission engages fixed 5
th gear.
Restarting is in 3rd gear.
–in the event of short circuit-:
No defect mode.
DF038Turbine speed sensor circuit If the fault occurs while driving:
Gear fixed. Restarting is in fixed 3
rd gear.
DF067Lever switch circuit No defect mode.
DF084Multiplex network If the fault occurs while driving, the
transmission engages fixed 5
th gear.
Restarting is in 3rd gear.
DF085EVS1 shift solenoid valve circuit – in the event of open circuit or short circuit+:
Fixed 5
th gear engaged.
Restarting is in 5th gear.
–in the event of short circuit-:
No defect mode.
DF086ESV2* shift solenoid valve circuit Fixed 5
th gear engaged.
Restarting is in 3rd gear.
DF091"LS"* pressure regulation solenoid
valve circuitNo defect mode.
DF093Manual sequential controls circuit No defect mode.
DF095Gear lever lock electromagnet circuit No defect mode.
DF097Converter lockup No defect mode.
DF108Effective average torque multiplex
signalIf the fault occurs while driving, the gearbox
engages fixed 5
th gear. Restarting is in 3rd
gear.
DF171Vehicle speed sensor circuit If the fault occurs while driving:
Gear fixed. Restarting is in fixed 3
rd gear.
DF178Accelerator pedal position No defect mode.
DF183No UCH multiplex signal. No defect mode.
DF186No injection multiplex signal If the fault occurs while driving, the gearbox
engages fixed 5
th gear.
Restarting is in 3rd gear.
DF230Signal: multiplex speed vehicle invalid No defect mode.
MR-372-J84-23A000$270.mif
Page 22 of 162

AUTOMATIC TRANSMISSION
Fault finding - Replacement of components
23A
23A-22V3 MR-372-J84-23A000$270.mif
AJ0 BVA
Vdiag No.: 04, 05
Tool fault Diagnostic tool title Defect modes
DF236Invalid engine speed multiplex signal No defect mode.
DF238Signal: raw engine torque multiplex
signal*If the fault occurs while driving, the gearbox
engages fixed 5
th gear.
Restarting is in 3rd gear.
DF256Erratic gear jumping – If caused by brake 2 solenoid valve, system
switches to fixed 3
rd or 5th gear safe mode.
–If caused by clutch 2 solenoid valve, system
switches to fixed 2
nd or 6th gear safe mode.
–If caused by clutch 3 solenoid valve, system
switches to fixed 2
nd, 3rd or 5th gear safe
mode.
–If caused by clutch 1 solenoid valve, system
switches to fixed 3
rd, 5th or 6th gear safe
mode.
In all cases, restarting is in 3
rd gear.
DF273Clutch 1 solenoid valve circuit If the fault occurs while driving, the
transmission engages fixed 5
th gear.
Restarting in fixed 5th gear (no more gear
changes).
DF274Clutch 2 solenoid valve circuit – in the event of open circuit or short circuit+:
No defect mode.
–in the event of short circuit-:
If the fault occurs while driving, the
transmission engages fixed 5
th gear.
Restarting in fixed 3rd gear (no more gear
changes)
DF275Clutch 3 solenoid valve circuit – in the event of open circuit or short circuit+:
No defect mode.
–in the event of short circuit-:
If the fault occurs while driving, the
transmission engages fixed 5
th gear.
Restarting in fixed 5th gear (no gear change)
DF289Automatic transmission multiplex
signalNo defect mode.
DF290Multiplexed ABS signal No defect mode.
DF298Gear shifts – If caused by brake 2 solenoid valve, system
switches to fixed 6
th gear safe mode.
–If caused by clutch 2 solenoid valve, system
switches to fixed 5
th gear safe mode.
Restarting in 3rd gear.
–If caused by clutch 3 solenoid valve, system
switches to fixed 5
th gear safe mode.
Page 23 of 162
AUTOMATIC TRANSMISSION
Fault finding - Replacement of components
23A
23A-23V3 MR-372-J84-23A000$270.mif
AJ0 BVA
Vdiag No.: 04, 05
Tool fault Diagnostic tool title Defect modes
DF300Brake 2 solenoid valve circuit – in the event of open circuit or short circuit+:
No defect mode.
–in the event of short circuit-:
If the fault occurs while driving, the
transmission engages fixed 5
th gear.
Restarting in fixed 3rd gear (no gear change)
DF301Clutch 1 pressure switch circuit No defect mode.
DF302Clutch 2 pressure switch circuit No defect mode.
DF303Clutch 3 pressure switch circuit No defect mode.
DF304Brake 1 pressure switch circuit No defect mode.
DF305Brake 2 pressure switch circuit No defect mode.
DF306Lock-up/brake 1 solenoid valve circuit Fixed 5
th gear engaged.
Restarting in fixed 3rd gear (no gear change).
DF307Engine braking No defect mode.
DF308Computer earth Fixed 5
th gear engaged.
Page 24 of 162

AUTOMATIC TRANSMISSION
Fault finding - Replacement of components
23A
23A-24V3 MR-372-J84-23A000$270.mif
AJ0 BVA
Vdiag No.: 04, 05
Replacing the transmission computer:
Remove the automatic transmission computer (see MR 370 mechanical, 23A, Automatic transmission,
Automatic transmission computer, Removal - Refitting).
Refit the automatic transmission computer (see MR 370 mechanical, 23A, Automatic transmission,
Automatic transmission computer, Removal - Refitting).
Establish dialogue with the diagnostic tool.
Use command VP001 Enter VIN.
Run command VP009 Write last After-Sales Service operation date.
Do not carry out any automatic programming if replacing the automatic transmission computer. Automatic
programming is finalised when the vehicle is driven.
In order to optimise the automatic programming before delivering the vehicle to the customer, apply the
"Programming procedure" shown below.
Replacing the hydraulic distributor:
Remove the transmission hydraulic distributor (see MR 370 mechanical, 23A, Automatic transmission,
Hydraulic distributor, Removal - Refitting).
Refit the transmission hydraulic distributor (see MR 370 Mechanical, 23A, Automatic transmission, Hydraulic
distributor, Removal - Refitting).
Replacing the automatic transmission
Remove the transmission (see MR 370,Mechanical, 23A, Automatic transmission, Removal - Refitting).
Refit the transmission (see MR 370, Mechanical, 23A, Automatic transmission, Removal - Refitting).
Establish communication with the diagnostic tool.
Initialise all the programming, use the command RZ009 Self-adapting clearing (Vdiag05 only).
Run command VP009 Write last After-Sales Service operation date.
The self-programming functions are performed when the vehicle is being driven.
In order to optimise the automatic programming before delivering the vehicle to the customer, apply the
"Programming procedure" shown below.
* APV: After-SalesPROGRAMMING PROCEDURE:
Programming conditions:
The automatic gearbox oil temperature should be between 60˚C and 100˚C.
Stationary, engine running, brake pedal depressed:
Engage neutral at least 5 times to consolidate the programming.
While driving:
Engage the same gear at least 5 times (i.e. in the same conditions) to consolidate the programming.
Note:
Gear changes are slow and harsh the first few times the vehicle is driven, until the automatic transmission computer
has carried out its automatic programming.
During upshifts and downshifts, the system analyses variations in oil pressure, components (play in the brakes and
clutches, changes to spring stiffness due to ageing) and input torque, then corrects them in order to maintain the
quality of gear changes.
The system analyses the turbine speed during the 3 phases of drag reduction (selection of Neutral when stationary,
regulation during drag reduction and deselection of Neutral) and corrects this speed by adjusting the converter
lock-up solenoid valve pressure.