If fluid level is definitely OK, then this is indicating a fault somewhere in the HICAS system. There is a self-diagnostic function built into the HICAS control unit, but it is a fiddly process to access. However, worth a try:
1. Ignition switch off
2. Set shift lever to neutral (auto or manual - auto can also use "P")
3. Ignition switch on and immediately start engine
4. Within a ten second period from starting the engine, turn steering wheel from left to right (at least 20 degrees from centre position each way) 5 times and press brake pedal 5 times.
HICAS is ready to input self-diagnosis conditions, so now:
1. Press and release brake pedal
2. Turn steering wheel left to right by at least 20 degrees each way
3.M/T - press clutch pedal and select any gear, return to neutral and disengage clutch. A/T - release and re-engage parking brake. Move shift lever to any position other than "P" or "N". Return to "P".
4. Drive car at least 3 metres forward at at least 1 mph.
HICAS warning lamp on dashboard will now flash - if no faults, you will see regular flashes at 4 per second.
For system malfunction, fail-safe mode may or may not have been triggered:
If fail-safe triggered, then light will flash ten times in 5 seconds followed by a 5 second gap, followed by 9 individual brief (tenth of a second) flashes with two second gaps between. If any flash is seen for one second, this indicates the numerical value of the fault. So, count the short flashes and make a note of any number in the sequence where the flash is longer than the rest. Sequence will repeat when completed, so you'll get another chance (and another, and another...up to 5 minutes).
If fail-safe is not triggered, the display and readings will be the same as described above, but the first 5 seconds will be the HICAS light ON continuously, not flashing rapidly.
Fault codes are:
1. HICAS solenoid valve RH
2. HICAS solenoid valve LH
3. Fail-safe valve
4. Power steering solenoid valve
5. Speed sensor
6. Steering angle sensor
7. Steering neutral position sensor
8. A/T parking brake sensor; M/T clutch sensor
9. A/T inhibitor sensor; M/T neutral sensor
Diagnostic mode is cancelled when you switch the ignition off, or after 5 minutes of trying to give you the codes, or if you drive the car over 19 mph.
Any work done on the steering wheel or column recently? Misalignment or damage to the steering angle / neutral position sensor is most likely.
Any work done on gearbox or in vicinity of gearbox recently? Speed sensor or connector damage likely. Does the speedo play up or give spurious readings?
Any work done on the instrument cluster recently? e.g. delimiter / speed convertor fitted? This could cause HICAS problems with some conversions.
Can you feel the HICAS behaving abnormally under standard driving conditions? Any "kick" or abnormal movement from the rear? Is steering light at low speed, becoming heavier at high speed as designed?
