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.
