Page 4 of 162
AUTOMATIC TRANSMISSION
Fault finding - Introduction
23A
23A-4V3 MR-372-J84-23A000$045.mif
AJ0 BVA
Vdiag No.: 04, 05
4. FAULT FINDING PROCEDURE
Perform a pre-diagnostic on the
system
Print the system fault finding log
(available on CLIP and in the
Workshop Repair Manual or
Technical Note)
Connect CLIP
no
Dialogue with
computer?
yes
Read the faults
no
Faults present
yes
Deal with present faults
Deal with stored faults
no
The cause is still
presentFault
solved
yes
See ALP no. 1
Conformity check
no
The cause is still
presentFault
solved
yes
Use fault finding charts (ALPs)
no
The cause is still
presentFault
solved
yes
Contact the Techline with the
completed fault finding log
Page 9 of 162

AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 9V3 MR-372-J84-23A000$135.mif
AJ0 BVA
Vdiag No.: 04, 05AUTOMATIC TRANSMISSION
Fault finding - Role of components
Role of main automatic transmission components
Automatic transmission computer:
The gearbox computer is used to manage the entire system.
Its role is to define the optimum operating mode for the automatic transmission (modify the torque transmitted to the
drive wheels by the automatic transmission), inform the driver (instrument panel, information display, buzzer) and
communicate with the other computers.
To carry out this function, the transmission computer takes account of:
–the operation of the gearbox,
–signals exchanged with other computers,
–driver requests.
Transmission oil temperature sensor:
Its role is to inform the automatic transmission computer of the transmission oil temperature.
Transmission input speed sensor:
Its role is to inform the automatic transmission computer of the turbine speed.
Transmission output speed sensor:
Its role is to inform the automatic transmission computer of the vehicle speed.
Brake light switch:
Its role is to inform the automatic transmission computer that the driver has depressed the brake pedal.
Multifunction switch:
Its role is to inform the automatic transmission computer of the gear lever position.
Shift-lock:
The role of this function is to lock the lever in position "P" and to immobilise the vehicle when stationary.
Solenoid valves:
The solenoid valves are fitted in the factory and cannot be removed from the hydraulic distributor to ensure optimum
gearbox operation, therefore they cannot be replaced separately.
The automatic transmission has two types of solenoid valve:
–2 "all or nothing" solenoid valves,
–6 "progressive" solenoid valves.
Of these 8 solenoid valves, 7 are used to control gear changes in automatic and manual modes, and one solenoid
valve controls the oil pressure in the automatic transmission hydraulic distributor.
Instrument panel display:
The purpose of this function is to manage the transmission of multiplex line signals required for the instrument panel
display.
On the instrument panel:
–a fault warning light,
–a message on the instrument panel in case of irregularity,
–an information display: gear lever position/gear engaged/brake pedal depressed indicator light/lever position in P
or N request indicator light.
On the gear lever:
–Position: P / R / N / D / M+/-,
–Shift-lock: lever lock.
MR-372-J84-23A000$135.mif
Page 10 of 162
AUTOMATIC TRANSMISSION
Fault finding - Operating diagram
23A
23A - 10V3 MR-372-J84-23A000$180.mif
AJ0 BVA
Vdiag No.: 04, 05AUTOMATIC TRANSMISSION
Fault finding - Operating diagram
Line pressure
OIL PUMP
Hydraulic
distributor
Primary regulation valve (pressure regulating valve)
LS pressure regulation solenoid valve
Manual valve
Clutch
modulating
solenoid valve 1
Clutch
modulating
solenoid valve 2Clutch
modulating
solenoid valve 3Brake
modulating
solenoid valve 2Modulating solenoid
valve
lock-up/brake 1
Sequence
solenoid valve 1Sequence solenoid
valve 2
Clutch 1 Clutch 2 Clutch 3 Brake 2Brake
1Torque
converter
lock-up
Hydraulic receivers
MR-372-J84-23A000$180.mif
Page 13 of 162
AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 13V3 MR-372-J84-23A000$225.mif
AJ0 BVA
Vdiag No.: 04, 05
"Automatic transmission management" FUNCTION:
Purpose of this function:
This function enables the automatic transmission computer to define the gear change programs.
Position of multifunction switch and its associated tracks on the computer:Multifunction switch:
Internal switches
(see table below)
"Automatic
transmission
management"
function:Modes: automatic or
manual
Oil temperature
sensor: Oil
temperatureGear upshifts or
downshifts in
manual position
Shift pattern control
(on lever)
M+, M-Gear lever position:
P, R, N, D
Position
TrackPRND
2
1
3
4
56
Page 14 of 162
AUTOMATIC TRANSMISSION
Fault finding - Role of components
23A
23A - 14V3 MR-372-J84-23A000$225.mif
AJ0 BVA
Vdiag No.: 04, 05
"GEAR CHANGE" FUNCTION:
Purpose of this function:
The purpose of this function is to control gear changes in automatic and manual modes.
"Lever selection"
function
"Gear
change"
functionClutch 1
solenoid valve
Brake pedal action Brake 2 solenoid valve
Vehicle speed Clutch 2 solenoid valve
Turbine speed Clutch 3 solenoid valve
Lock-up and brake 1
solenoid valve
Solenoid valve EVS1
Solenoid valve EVS2
–Accelerator
–Engine speed
–Gear change inhibition
–...CAN
"Torque management"
function
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 25 of 162
AUTOMATIC TRANSMISSION
Diagnostics - Configuration and programming23A
23A - 25V3 MR-372-J84-23A000$315.mif
AJ0 BVA
Vdiag No.: 04, 05AUTOMATIC TRANSMISSION
Diagnostics - Configuration and programming
SETTINGS
VP001: "Enter VIN".
This command permits manual entry of the vehicle's VIN into the computer.
Use this command each time the computer is replaced or (re)programmed.
VP009: "Write last APV* operation date".
Run this command after replacing or removing - refitting the transmission computer and the automatic transmission.
This command is used to enter the date of the last service operation.
Do not carry out any programming operation if replacing a component; automatic programming is carried
out during driving (See Replacement of components, Programming procedure).
* APV: After-Sales
MR-372-J84-23A000$315.mif
Page 26 of 162

AUTOMATIC TRANSMISSION
Fault finding - Fault summary table
23A
23A - 26V3 MR-372-J84-23A000$360.mif
AJ0 BVA
Vdiag No.: 04, 05AUTOMATIC TRANSMISSION
Fault finding - Fault summary table
*signal: signal
*EVS1 = sequence solenoid valve 1
*EVS2 = sequence solenoid valve 2
*LS = line pressure regulation solenoid valveTool fault Associated DTC Diagnostic tool title
DF023710 Transmission oil temperature sensor circuit
DF038715 Turbine speed sensor circuit
DF067705 Lever position switch circuit
DF084C073 Multiplex network
DF0851753 EVS1* shift solenoid circuit
DF0861758 "ESV2"* shift solenoid circuit
DF091748 "LS"* pressure regulation solenoid valve circuit
DF093826 Manual sequential controls circuit
DF095928 Gear lever lock electromagnet circuit
DF097740 Converter lock-up
DF1085300 Effective average torque multiplex signal
DF171720 Vehicle speed sensor circuit
DF1785600 Accelerator pedal position
DF183C140 No UCH multiplex signal
DF186C100 No injection multiplex signal
DF230C415 Invalid vehicle speed multiplex signal
DF236725 Invalid engine speed multiplex signal
DF2384073 Invalid raw engine torque multiplex signal*
DF256730 Erratic gear jumping
DF273753 Clutch 1 solenoid valve circuit
DF274763 Clutch 2 solenoid valve circuit
DF275768 Clutch 3 solenoid valve circuit
DF2891840 Automatic transmission multiplex signal
DF290C121 Multiplexed ABS signal
DF298893 Gear shifts
DF300758 Brake 2 solenoid valve circuit
DF301751 Clutch 1 pressure switch circuit
MR-372-J84-23A000$360.mif