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 - 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 - 15V6 MR-366-X84-36B000$462_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12POWER ASSISTED STEERING
Fault finding - Interpretation of faults
DF002
PRESENT
OR
STOREDCOMPUTER
DEF : Computer fault
WARNING
Consult the fault contexts.
If PR143 Internal fault codes = 46 and the battery voltage when the fault occurs (PR108) is above 9 V, do not
clear the fault; contact the Techline.
If PR143 Internal fault code = 46 and the battery voltage when the fault occurs (PR108) is less than or equal to
9 V, run fault finding on the battery and charge circuit and clear the fault.
For other values of PR143, do not clear the fault, contact the Techline.
NOTESConditions for applying the fault finding procedure to stored faults:
The fault is declared present after starting 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.
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_DF002/DAETRW_V08_DF002/DAETRW_V06_DF002/DAETRW_V0C_DF002/
DAETRW_V12_DF002
MR-366-X84-36B000$462_eng.mif
POWER ASSISTED STEERING
Fault finding - Interpretation of faults
36B
36B - 18V6 MR-366-X84-36B000$462_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
DF035
PRESENT
OR
STOREDVARIABLE POWER ASSISTED STEERING MOTOR
DEF : Internal electronic fault
WARNING
For TRW EPAS Vdiag 04 only, consult the fault contexts.
–If PR143 Internal fault code = 58 and if the battery voltage when the fault occurs (PR108) is above 9 V, do not
clear the fault; contact the Techline.
–If PR143 Internal fault code = 58 and if the battery voltage when the fault occurs (PR108) is less than or equal
to 9 V, run fault finding on the battery and charge circuit.
–For other values of PR143, do not clear the fault, contact the Techline.
For the other Vdiag of TRW EPAS, do not clear the fault, contact the Techline.
NOTESConditions for applying the fault finding procedure to stored faults:
The fault is declared present after starting or a steering wheel movement from full lock
to full lock.
Special notes:
Apply the fault finding procedure only on Vdiag 04.
For Vdiag 06, 08, 0C and 12, do not clear the fault and contact the Techline.
–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.
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_DF035/DAETRW_V08_DF035/DAETRW_V06_DF035/DAETRW_V0C_DF035/
DAETRW_V12_DF035
POWER ASSISTED STEERING
Fault finding - Interpretation of statuses
36B
36B - 34V6 MR-366-X84-36B000$660_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12POWER ASSISTED STEERING
Fault finding - Interpretation of statuses
ET020
PROGRAMMING THE STEERING WHEEL ANGLE SENSOR
NOTESSpecial notes:
–The status is declared as correct when it is STATUS 4 (nominal mode). Otherwise,
apply this fault finding procedure.
–An unprogrammed steering wheel angle sensor will cause the Service warning light
to come on.
–If the steering wheel angle sensor has never been programmed, the Service warning
light will flash rapidly until the index position is detected.
VARIOUS POSSIBLE STATUS VALUES (with the meaning):
STATUS 1–Steering wheel index not detected.
–Straight ahead wheel position not programmed.
–Invalid angle value.
–NOT PROGRAMMED: Program the steering wheel angle sensor.
STATUS 2–Steering wheel index detected.
–Straight ahead wheel position not programmed.
–Invalid angle value.
–NOT PROGRAMMED: Program the steering wheel angle sensor.
STATUS 3–Steering wheel index not detected.
–Straight ahead wheel position not programmed.
–Invalid angle value.
–PROGRAMMING DONE, CONFIRM ANGLE: Turn the steering wheel to right full lock, and then
left full lock; then slowly return to the centre point and go slightly beyond.
STATUS 4–Straight ahead wheel position not programmed.
–Valid angle value.
–PROGRAMMING COMPLETE
Note:
A present or stored fault may prevent the change to STATUS 4.
AFTER REPAIRRun a system fault check.
Repeat the conformity check.
DAETRW_V04_ET020/DAETRW_V08_ET020/DAETRW_V06_ET020/ DAETRW_V0C_ET020/
DAETRW_V12_ET020
MR-366-X84-36B000$660_eng.mif
POWER ASSISTED STEERING
Fault finding - Interpretation of statuses
36B
36B - 37V6 MR-366-X84-36B000$660_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12
ET026
COMPUTER CALIBRATION
Configuration 0
Configuration 1
Configuration 2
Configuration 3
Configuration 4
Configuration 5
NOTESNone
WARNING
Use the information from the diagnostic tool.
Incorrect calibration can damage the function.
If the computer calibration is not as you want it (consult the help for ET026 on the Clip tool, redefine the vehicle
specifications using command SC001 Computer calibration.
AFTER REPAIRRun a system fault check.
Repeat the conformity check.
DAETRW_V04_ET026/DAETRW_V08_ET026/DAETRW_V06_ET026/ DAETRW_V0C_ET026/
DAETRW_V12_ET026
POWER ASSISTED STEERING
Fault finding - Customer complaints
36B
36B - 45V6 MR-366-X84-36B000$858_eng.mif
PAS
Vdiag No.: 04, 06, 08, 0C
and 12POWER ASSISTED STEERING
Fault finding - Customer complaints
NO DIALOGUE WITH THE COMPUTER ALP1
LOSS OF VEHICLE ASSISTANCE WITHOUT WARNING ALP2
POOR VEHICLE HANDLINGALP3
THE STEERING WHEEL DOES NOT RETURN BY ITSELF TO THE
CENTRE AT LOW VEHICLE SPEED: STEERING WHEEL SELF-
CENTRING INACTIVEALP4
UNDER-ASSISTANCE AT LOW SPEED AND OVER-ASSISTANCE AT
HIGH SPEEDALP5
TOO LITTLE ASSISTANCEALP6
ASSISTANCE AVAILABLE FOR 5 MIN. AFTER SWITCHING OFF THE
IGNITIONALP7
ASSISTANCE AVAILABLE BUT CHECK STEERING WARNING
MESSAGE DISPLAYED AND SERVICE WARNING LIGHT LIT
CONSTANTLY OR FLASHING AT 8 HzALP8
Vdiag 06 and 12 only
SERVICE INDICATOR LIGHT AND CHECK STEERING MESSAGE
COME ON STRAIGHT AWAYALP9
THE VEHICLE PULLS TO THE RIGHT OR TO THE LEFT ALP10
THE ENGINE DOES NOT START AND THE "STEERING NOT
UNLOCKED" IS DISPLAYED
OR
"STEERING NOT LOCKED" AFTER THE IGNITION IS SWITCHED
OFFALP11
MR-366-X84-36B000$858_eng.mif