NO.4 STEERING WHEEL STIFFENS WHILE DRIVING

id060300950500

4

Steering wheel stiffens while driving
POSSIBLE CAUSE
•  System overheating prevention control is performed by EPS control module.
―  Steering mechanism is turned from lock to lock frequently.
Note
•  If high-grip tires are installed, steering torque (EPS motor control current) increases making it easier for EPS system to operate system overheating prevention control.
•  EPS system detects a malfunction. (EPS warning light illuminates.)
•  Steering gear and linkage malfunction
•  Wheel alignment adjustment malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY EPS WARNING LIGHT CONDITION
•  Switch the ignition to ON (engine ON).
•  Verify the EPS warning light illumination condition.
•  Does the EPS warning light illuminate?
Yes
Perform the symptom troubleshooting “NO.2 ELECTRIC POWER STEERING (EPS) WARNING LIGHT DOES NOT GO OUT EVEN THOUGH ENGINE HAS STARTED”.
(See NO.2 ELECTRIC POWER STEERING (EPS) WARNING LIGHT DOES NOT GO OUT EVEN THOUGH ENGINE HAS STARTED.)
No
Go to the next step.
2
VERIFY IF SYSTEM OVERHEATING PREVENTION CONTROL IS BEING PERFORMED AT PRESENT
•  Access the following EPS control module PIDs using the M-MDS.
―  OH_PRO_C_45
―  OH_PRO_C_60
•  Are any of the monitors displaying "Yes"?
Yes
The cause is the EPS system operating the system overheating prevention control.
•  After approx. 45 min have elapsed since the engine was stopped, verify if the malfunction symptom recurs.
―  If the malfunction is not resolved, go to Step 4.
No
Go to the next step.
3
VERIFY IF SYSTEM OVERHEATING PREVENTION CONTROL WAS PERFORMED IN PAST
•  Access the following EPS control module PIDs using the M-MDS.
―  OH_PRO_H_45
―  OH_PRO_H_60
•  Are any of the monitors displaying "Yes"?
Yes
Note
•  The period in which the system overheating prevention control operated can be specified by the EPS control module PID, OH_AGING_45 and OH_AGING_60 monitoring values, and the number of times the customer has switched the ignition to ON. However, the number of times the ignition is switched to ON while performing the diagnostic procedure is included.
The cause is the EPS system operating the system overheating prevention control in the past.
•  Verify if the malfunction symptom recurs.
―  If the malfunction is not resolved, go to the next step.
No
Go to the next step.
4
VERIFY STEERING FORCE
•  Inspect the steering force.
•  Is the steering force within the specification?
Yes
Inspect the steering gear and linkage.
(See STEERING GEAR AND LINKAGE INSPECTION.)
Repair or replace the malfunctioning part according to the inspection results.
No
Inspect the front wheel alignment.
(See FRONT WHEEL ALIGNMENT [European (L.H.D., U.K.) Specs.].)
(See FRONT WHEEL ALIGNMENT [Australian Specs. and General (L.H.D., R.H.D.) Specs.].)
•  If not within the specification, adjust the force.