POWER ASSISTED STEERING
Fault finding - System operation
36B
36B - 7V6 MR-366-X84-36B000$132_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12POWER ASSISTED STEERING
Fault finding - System operation
INPUTS OUTPUTS
Vehicle speed signal (sent by the
Anti-lock Braking System computer)
ELECTRIC POWER
ASSISTED
STEERING
COMPUTER
Angle sensor signal (Electronic
stability program signal)
Engine status signal
(running, stopped, actuated
by the starter or stalled)
CAN bus status signal Instrument panel signals
Diagnostic socket
Power supply (permanent +)
Supply (+ after ignition feed) Diagnostic socket
Earth
CAN connection
Wire connection
MR-366-X84-36B000$132_eng.mif
POWER ASSISTED STEERING
Fault finding - System operation
36B
36B - 8V6 MR-366-X84-36B000$132_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
SYSTEM OPERATION
On this vehicle, the steering system is power-assisted by an electric motor (mounted on the steering column). The
driver's actions are translated by a torque sensor, which measures the force applied to the steering wheel by the
driver, and by an angle measuring sensor. The steering wheel angle signal is used by the electronic stability program
computer for the trajectory control programming.
Assistance is provided by means of an electric motor which applies an appropriate torque to the steering column, in
one direction or the other.
A computer controls this assistance according to several vehicle environment parameters, including the vehicle
speed.
NOTE
Depending on the operating conditions and the operations performed on the vehicle before switching on the ignition,
the assistance system may take a certain time to be activated after engine starting; this also applies after battery cut-
off or switching off the ignition.
Fault finding warning lights illumination programming:
Slow flashing of the Service warning light at 2 Hz: the electric power steering system is in fault finding mode.
Rapid flashing of the Service warning light at 8 Hz accompanied by the Check steering message: the steering
wheel angle sensor is not calibrated and not indexed.
Service warning light continuously lit with Check steering displayed on instrument panel: signal received by the
EPAS computer.
–assistance equal to that provided at a speed of 24 mph (40 km/h) if vehicle speed signal is absent or incorrect,
–angle sensor signal invalid: steering wheel angle sensor not calibrated (no active recall).
STOP warning light continuously lit with steering defective displayed on the instrument panel: fault in the EPAS
system.
If the fault is still present after repair, contact the Techline.
Angle sensor programming (initialisation)
The steering wheel angle sensor is initialised after the ignition is switched on. The sensor is not initialised until the
steering wheel has gone through a quarter turn left or right. If this turn is not carried out, the steering wheel angle
value reading will be 1.2 degrees higher or lower than the actual value.
Check consistency of ET020 Steering wheel angle sensor programming. Note:
If the computer detects a fault, the level of assistance can be modified depending on how serious the fault is.
An incorrect or absent vehicle speed signal results in fixed, unsatisfactory assistance.
POWER ASSISTED STEERING
Fault finding - Replacement of components36B
36B - 10V6 MR-366-X84-36B000$264_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12POWER ASSISTED STEERING
Fault finding - Replacement of components
The power-assisted steering computer cannot be separated from the steering column.
Before replacing the electric power assisted steering computer, the battery must be disconnected.
Procedure to follow after battery disconnection:
Every time the battery is disconnected, the steering wheel angle is invalid (remains at 0) and status ET020 is at
Status 3.
Following a road test, this will result in a fault in the Electronic Stability Program.
Therefore, every time the battery is disconnected, turn the steering wheel from lock to lock, then bring back the
steering wheel to the centre point with the wheels set straight ahead and the engine running.
Check that ET020 Steering wheel angle sensor programming becomes Status 4.
If the fault is still present, stop and restart the engine without pressing the ESP button and repeat the procedure
above.
Replacing the computer:
Each time the Electric Power Assisted Steering computer is replaced, configure the computer to the vehicle (see
SC001 Computer calibration) and program the steering wheel angle sensor (VP004 Steering wheel angle sensor
programming).
The computer must only be replaced with the battery disconnected.
MR-366-X84-36B000$264_eng.mif
POWER ASSISTED STEERING
Fault finding - Configurations and programming36B
36B - 11V6 MR-366-X84-36B000$330_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12POWER ASSISTED STEERING
Fault finding - Configurations and programming
VP004: STEERING WHEEL ANGLE SENSOR PROGRAMMING
NOTESThis programming procedure is performed after replacing the EPAS computer.
WARNING
Programming the steering wheel angle sensor means programming the 0 angle (wheels straight ahead position).
It must be done for any blank computer, and every time it is requested in this note.
The absence of or incorrect programming of this sensor will illuminate the Service warning light and create an
Electronic Stability Program fault.
OPERATIONS TO PERFORM BEFORE PROGRAMMING
–With the ignition on or engine running (to obtain maximum steering assistance), turn the steering wheel to full
left lock and then to full right lock,
–position the vehicle with the wheels straight ahead and the steering at the centre point (driving in a straight line),
–run the command by pressing the CONFIRM button,
–while the COMMAND IN PROGRESS message is displayed, turn the steering wheel a quarter of a turn from left
to right.
–Once the COMMAND COMPLETE message is displayed, exit fault finding mode (close dialogue with the
computer without switching off the tool) and then switch off the vehicle's ignition for 15 seconds minimum for
the programming to be registered.
Note:
To obtain a precise position with the wheels set straight ahead (driving in a straight line), this operation must be
performed on a front axle adjustment bench (especially for vehicles fitted with ESP).
OPERATIONS TO PERFORM AFTER PROGRAMMING
–Switch on the ignition and establish dialogue with the EPAS computer,
–turn the steering wheel to full left lock and then to full right lock,
–check that the programming has been properly registered: ET020 Steering wheel angle sensor programming
should be STATUS 4,
–check the conformity of the angle value by consulting parameter PR121 Steering wheel angle,
–check that there are no faults,
–carry out the necessary repairs, consulting the fault finding manual.
IMPORTANT
If the vehicle is fitted with ESP, establish dialogue with the ABS/ESP computer after the operation; if the function
is available (depending on computer version) clear the ESP sensor programming using command RZ003.
Make sure there are no ESP faults: make the necessary repairs, consulting the fault finding manual.
MR-366-X84-36B000$330_eng.mif
POWER ASSISTED STEERING
Fault finding - Configurations and programming36B
36B - 12V6 MR-366-X84-36B000$330_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
SC001: COMPUTER CALIBRATION
NOTESThis configuration is performed after replacing the EPAS computer.
WARNING
The computer is supplied with the default calibration 0.
An incorrect configuration may damage the function.
Command SC001 is used to define the vehicle specifications.
The configuration is determined by the following specifications:
–Vehicle type:
–The diameter of the vehicle wheel rims:
–The vehicle engine type and gearbox type:
CALIBRATION PROCEDURE:
–Connect the diagnostic tool and select EPAS,
–select command SC001 Computer calibration,
–configure the computer in line with the vehicle definition,
–exit fault finding mode without switching off the tool (close the application only),
–switch off the ignition,
–wait 15 seconds for the end of power-Iatch then restart,
–make sure that the configuration reading corresponds to the desired calibration:
LC005 or ET026 Computer calibration.
POWER ASSISTED STEERING
Fault finding - Interpretation of faults
36B
36B - 16V6 MR-366-X84-36B000$462_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
DF020
PRESENT
OR
STOREDCOMPUTER SUPPLY VOLTAGE
DEF : Computer internal voltage
NOTESSpecial notes:
Although stored in the computer, this fault is not caused by an electric power-assisted
steering failure, but by a poor electrical supply.
Conditions for applying the fault finding procedure to stored faults:
The fault is declared present after the engine is started or a steering wheel movement
from full lock to full lock.
–Check the condition and connection of the battery terminals.
–Check that the EPAS black 2-track connector is correctly locked.
–Check that the EPAS black 8-track connector is correctly locked.
–Check the condition and conformity of the EPAS fuses: on the power fuse board (70A) and on the UPC (5A).
–Check the conformity of PR108 Computer feed voltage: 12 V < PR108 < 16 V.
Check that:
–there is a + 12 V before ignition feed on track 1 of the electric power steering black 2-track connector,
–there is an earth on track 2 of the electric power steering black 2-track connector,
–there is a + 12 V after ignition feed on track 8 of the steering column assembly black 8-track connector.
If there is a repair procedure (see Technical Note 6015A, Repairing electrical wiring, Wiring: Precautions for
repair), repair the wiring, otherwise change the wiring.
Check the voltage of the battery and the charge circuit.
Repair if necessary.
If the fault is still present, contact the Techline.
AFTER REPAIRCarry out a road test followed by a complete test with the diagnostic tool.
DAETRW_V04_DF020/DAETRW_V08_DF020/DAETRW_V06_DF020/DAETRW_V0C_DF020/
DAETRW_V12_DF020
POWER ASSISTED STEERING
Fault finding - Interpretation of faults
36B
36B - 17V6 MR-366-X84-36B000$462_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
DF033
PRESENT
OR
STOREDMULTIPLEX NETWORK
DEF : CAN connection fault
NOTESSpecial notes:
Although stored in the computer, this fault is not caused by an electric power-assisted
steering failure, but by a multiplex network fault.
Conditions for applying the fault finding procedure to stored faults:
The fault is declared present after the engine is started or a steering wheel movement
from full lock to full lock.
Check that:
–there is a + 12 V before ignition feed on track 1 of the electric power steering black 2-track connector,
–there is an earth on track 2 of the electric power steering black 2-track connector,
–there is a + 12 V after ignition feed on track 8 of the steering column assembly black 8-track connector.
If there is a repair procedure (see Technical Note 6015A, Repairing electrical wiring, Wiring: Precautions for
repair), repair the wiring, otherwise change the wiring.
Check the continuity of the wiring harness for the multiplex network (see 88B, Multiplexing):
Black 8-track connector track 5CAN_L
Black 8-track connector track 7CAN_H
If there is a repair procedure (see Technical Note 6015A, Repairing electrical wiring, Multiplex network: repair),
repair the multiplex connection, otherwise change the multiplex connection.
Check the continuity of the wiring harness for the multiplex network (see 88B, Multiplexing)
Black 8-track connector track 4CAN_L instrument panel
Black 8 track connector track 6CAN_H instrument panel
If there is a repair procedure (see Technical Note 6015A, Repairing electrical wiring, Multiplex network: repair),
repair the multiplex connection, otherwise change the multiplex connection.
Carry out a multiplex network test and deal with any faults.
If the fault is still present, contact the Techline.
AFTER REPAIRCarry out a road test followed by a complete test with the diagnostic tool.
DAETRW_V04_DF033/DAETRW_V08_DF033/DAETRW_V06_DF033/DAETRW_V0C_DF033/
DAETRW_V12_DF033
POWER ASSISTED STEERING
Fault finding - Interpretation of faults
36B
36B - 20V6 MR-366-X84-36B000$462_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
DF053
PRESENT
COMPUTER CONFIGURATION
DEF : Computer calibration not carried out
NOTESSpecial notes:
This fault appears after the engine is started.
Configure the computer using command SC001 Computer calibration, in line with the equipment and vehicle
type.
If the fault is still present, contact the Techline.
AFTER REPAIRCarry out a road test followed by a complete test with the diagnostic tool.
DAETRW_V04_DF053P/DAETRW_V08_DF053P/DAETRW_V06_DF053P/DAETRW_V0C_DF053P/
DAETRW_V12_DF053P