21B-8
MR-413-X44-21B000$177.mif
V2
21B
SEQUENTIAL GEARBOX
Fault finding - System operation
1. Sequential gearbox functions
The electrohydraulic system attached to the gearbox comprises two actuators, one for gear selection and changing,
the other for operating the clutch, and a hydraulic power unit which supplies power to the actuators.
The assembly is linked to the sequential gearbox computer, which itself is linked to the engine management
computer by a multiplex line connection. The gear lever is used to select gears: in automatic mode, gear changes
are controlled by the computer which uses auto-adaptive shift patterns; in manual mode, the driver moves a lever
which, via the computer, change the gears.
When the gear is changed, the sequential gearbox computer controls the engine management computer and the
torque in such a way as to reduce bucking, leaving the driver free to leave his foot on the accelerator pedal.
Description of user operation:
The interface between the driver and the sequential gearbox system inside the passenger compartment comprises:
–a gear lever (mechanical section and internal electronic section),
–a display,
–a buzzer.
Using this interface, the driver can:
–request gear changes (up or down),
–request a specific gear change (into neutral or reverse),
–switch between manual and automatic mode,
Description of passenger compartment control:
Description of gear lever positions:
–“S”: Standby: this is the only stable gear lever position. Each time the driver presses the lever, it returns to the S
position.
–“R”: Reverse: moving the lever to this position enables the driver to select reverse gear. Given the lever position
of the reverse function, if the movement is too slow, the sequential gearbox computer can read the N signal and
hence neutral is selected before reverse.
–“N”: Neutral: moving the lever to this position enables the driver to select neutral.
–“A/M”: AUTO/MANUAL: moving the lever to this position enables the driver to select either the manual mode (or
semi-automatic) or automatic mode. If AUTO mode is selected, moving the lever will enable the driver to select
manual mode, if manual mode is selected; moving the lever will enable the driver to select automatic mode. The automatic mode used by the sequential gearbox is based on the design of the DP0 automatic gearbox which
uses
shift patterns that adapt automatically to the driving style and road conditions.
The gear change is determined by a set of gear change graphs as a function of the accelerator pedal position and
the vehicle speed.
The sequential gearbox is a conventional manual gearbox with an electrohydraulic control.
Vdiag No: 04
MR-413-X44-21B000$177.mif
21B-11
MR-413-X44-21B000$177.mif
V2
Vdiag No: 04SEQUENTIAL GEARBOX
Fault finding - System operation21B
Lever operation:
–Each time the lever is moved, it returns to the “S” position automatically.
–When the vehicle has stopped and the engine is switched off and the key is in + after ignition feed position, lever
movements will only be registered if the driver depresses the brake pedal. In this case, all gears are available. The
number of gear changes possible is unlimited.
–When the vehicle has stopped and the engine is running, lever movements will only be registered if the driver
depresses the brake pedal. In this configuration, only gears N, 1, 2 and R are available.
–Position N only allows neutral to be engaged if the driver depresses the brake pedal.
–Position R enables reverse gear to be engaged. Reverse gear will only be engaged if the vehicle has stopped and
if the driver depresses the brake pedal. Engaging reverse when driving is prevented by the sequential gearbox
computer.
Display operation:
AUTO repeater
–As the display has an AUTO (A) symbol, it is possible to display the gear engaged at the same time as
AUTO mode.
Gear selection display
–Vehicle stopped or almost stopped: A new gear will only be displayed after confirmation that the gear has
really been engaged in the gearbox.
–Vehicle being driven: the change in the status of the display will depend on the driving mode selected:
In AUTO mode: simultaneous display of the AUTO mode and the gear engaged.
In MANUAL mode: engaged gear is displayed.
Display programming when gears cannot be engaged
–When a request would lead to engine overspeed or underspeed: the requested gear flashes then initial
gear reappears. Flashing ends after a delay.
–When there is a mechanical fault: application of the “retry” (1) program by the computer.
During retry: the requested gear flashes; then, the engaged gear is displayed on the instrument panel at
the end of the retry period. This program cannot be applied to neutral because the “N” position cannot
flash on the instrument panel; it remains lit.
(1) “RETRY”: If there is a mechanical fault engaging a gear (lower or higher), the computer will detect this
and will attempt to re-engage twice more; if this does not work, the requested gear will flash on the
instrument panel display and the gearbox will return to the gear used prior to this request.
21B-12
MR-413-X44-21B000$177.mif
V2
Vdiag No: 04SEQUENTIAL GEARBOX
Fault finding - System operation21B
Depress brake pedal symbol:
–The “depress brake” symbol lights up when there is:
–a request to change gear when stopped without the brake pedal applied,
–a request to start the engine with gear engaged without brake pedal applied,
–a request to select N when driving without brake pedal applied,
–a request to select AUTO, with the vehicle stationary, the engine running and 2
nd gear engaged.
–Depress brake pedal symbol goes out:
The symbol goes out if the driver depresses the brake pedal or after a delay.
In the event that the driver makes a request causing the gear requested to flash and the symbol to be displayed at
the same time, they will be synchronised and last for the same period of time.
Fault warning light:
This warning light comes on when a fault is detected by the sequential gearbox computer.Note:
If, while the symbol is lit, the driver depresses the brake pedal, the symbol will go out and the display will return to
its previous status (the lever request is not registered).
21B-42
MR-413-X44-21B000$413.mif
V2
SEQUENTIAL GEARBOX
Fault finding - Interpretation of faults
Vdiag No.: 04
21B
DF076
PRESENT
OR
STOREDCLUTCH CONTROL
1.DEF: Clutch inconsistency upon gear change
NOTESPriorities when dealing with a number of faults:
In the event of a number of faults, deal with faults DF068 Clutch position sensor
circuit, DF071 Clutch solenoid valve circuit and DF254 Clutch temperature.
Conditions for applying the fault finding procedure to stored faults:
The fault is declared present following harsh use of the clutch (prolonged hold on a
hill, PR095 Clutch temperature ≥ 248˚C).
Special notes:
Fault warning light comes on,
When PR095 Clutch temperature ≥ 248˚C, the buzzer is activated.
Check that the clutch is not slipping by performing a road test, driving with a low load and then up or down an
incline.
If the clutch slips, pull away several times with a low load and check if PR096 Clutch progressivity changes.
If the fault is still present, replace the clutch (see MR 411 Mechanical, 21B, Sequential gearbox).
AFTER REPAIRDeal with any faults displayed by the diagnostic tool.
Clear the computer memory.
Carry out a road test followed by another check with the diagnostic tool.
BVRJH1_V04_DF076
21B-74
MR-413-X44-21B000$472.mif
V2
SEQUENTIAL GEARBOX
Fault finding - Interpretation of faults
Vdiag No: 04
21B
DF259
PRESENT
OR
STOREDPRESSURE ACCUMULATOR
1.DEF : Pressure accumulator fault
NOTESConditions for applying the fault finding procedure to stored faults:
The fault is declared present after low nitrogen pressure has been recorded at least
40 times.
Special note:
–Fault warning light comes on when low nitrogen pressure has been recorded at
least 40 times.
–Engine stalls when the vehicle is slowing down.
–Gear change impossible when driving.
Replace the accumulator (see MR 411 Mechanical, 21B, Sequential gearbox, Pressure accumulator:
Removal - Refitting).
AFTER REPAIRDeal with any faults detected by the diagnostic tool.
Clear the computer memory.
Carry out a road test followed by another check with the diagnostic tool.
BVRJH1_V04_DF259
21B-83
MR-413-X44-21B000$649.mif
V2
SEQUENTIAL GEARBOX
Fault finding - Interpretation of statuses
Vdiag No: 04
21B
ET013
GEAR ENGAGED
STATUS
DEFINITIONThis status ET013 indicates the gear engaged and corresponds to the gear displayed
on the instrument panel:
●1: 1st
●
2: 2nd
●
3: 3rd
●
4: 4th
●
5: 5th
●
N: Neutral
●R: Reverse
NOTESNone
Engine stopped, ignition on
Check the specification of status ET013 each time the gear lever is moved:
●Gears 1st to 5th: push the lever forwards for the next gear up and backwards for the next gear down and
check how status ET013 changes each time the gear lever moves.
●Position N (neutral): when status ET013 is "1", push the lever to the right and check that status ET013 is
"N".
●Gear R (reverse): check status ET013 changes to "R" after depressing the brake pedal, pushing the lever to
the right and then to the rear.
If status ET013 is not correct, refer to the interpretation of faults DF069 "Selection position circuit" and DF070
"Engaging position sensor circuit".
AFTER REPAIRCarry out another fault finding check on the system.
Deal with any other faults.
Clear the stored faults.
BVRJH1_V04_ET013