HICAS Diagnostic:
Turbos come standard with High Capacity Actively Controlled Suspension, a fancy way to say 4 wheel steering. There's a visual diagnostic mode to check for problems in the HICAS functions. The 90-93 TTs have hydrolic HICAS running off the power steering pump, where '94+ utilizes electric actuators to handle the rear steering chores. Their codes are a little different, but the procedure is the same. It might required a few tries to make it work. Be persistant!


1. Ignition switch 'off' manual tranny in neutral or A/T in 'P' 

2. Start the engine 

3. Within 10 seconds after turning the key to 'ON', start the engine, turn steering wheel from left to right 20 degrees from neutral 5 times or more times & pump the brakes 5 times. Then press the brake pedal again to enter the test mode.

4. Turning the steering wheel left or right past 20 degrees from neutral will cause the rear wheels to turn slightly (~1 degree) (1.).

5. Drive the car forward 15 feet under 9mph to enter the full diagnostic mode. 

6. The HICAS dash light will flash a code indicating any problems. Long flash is first digit, short flash is 2nd digit. 

7. Diagnostic mode is exited when: ignition is turned off, vehicle speed exceeds 9mph, or diagnostic has operated for 5 minutes.

HICAS light codes for '90-'93:

1.  HICAS solenoid R.H.
2.  HICAS solenoid L.H.
3.  Cut-off valve
4.  Power Steering solenoid
5.  Vehicle Speed sensor
6.  Steering angle sensor
7.  Steering Neutral positon sensor
8.  A/T:  Parking Brake Sensor       M/T:  Clutch sensor
9.  A/T:  Inhibitor sensor                 M/T:  Neutral sensor

HICAS light codes for '94-'99:

11. HICAS control unit 
12. HICAS motor power supply not present 
13. HICAS motor output not present 
21. Vehicle speed signal not present 
22. Steering angle sensor angle signal not present 
23. Steering angle sensor neutral not present 
24. Rear main sensor input not present 
25. Rear sub sensor input not present 
31. Parking brake sensor input not present 
32. Inhibitor switch (A/T) or nuetral switch (M/T) input not present 
33. Engine speed signal not present 


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1.the HICAS actuator moving the rear wheels