If the HICAS warning light is on, it means that the system is not working properly and the car's handling may be compromised. You should take your car to a qualified mechanic as soon as possible to have the system inspected and repaired.
Here are some possible causes of the HICAS warning light:
* Low hydraulic fluid level
* Faulty hydraulic pump
* Faulty HICAS control unit
* Faulty rear wheel toe angle sensor
* Wiring problems