Removing HICAS Delete 4 Wheel Steering How to Guide

The HICAS system is Nissans' attempt at a super-handling 4 wheel steering type of thing, for anyone who's driven a car with 4 wheel steering in any sort of spirited driving, you realize pretty quickly that its less of an aid and more of a downfall.

You see, driving faster than 80 km/hr the system will become active, and as you turn around a corner or make quick steering changes, the rear wheels will turn one degree in and out, for a total three degree sweep while you're driving. This system works really well if you want to change lanes really fast, but if you're more into putting the car sideways in a four wheeled power slide, then the HICAS will become your worst enemy.
Rear subframe Nissan Skyline
HICAS rear steering rack - 2 lines plug into it just behind the differential
As the rear end steps out, the HICAS activates to counter the rear end slide, but because you expected the rear end to come out you've already begun to counter steer. So as you turn the wheel, the HICAS turns the rear wheels, and undoes what you've just done! Suddenly you're swerving wildly about battling the HICAS system for control of the rear end. It's a complete disaster and frankly a little dangerous. For even better control and handling look over this guide on Sway Bars, Understeer and Oversteer.
The solution is to yank it all out, the entire system, hoses, actuators, etc weighs approximately 60kg, so its a good way to shave some pounds off the already massive GTR. There are a few quick and simple solutions, that effectively lock out the HICAS but don't remove the weight, such as the Tomei kit which handles it electronically. There's also a number of kits that mechanically lock out the system by replacing the rear steering rack with a solid bar instead.
Hydraulic Lines and Solenoid
Rear lines and solenoid
This guide is how to completely remove the system. You should have a bucket handy through-out because as you remove each part, power steering fluid (which is corrosive) will leak everywhere. To begin, remove the power steering pump by loosening the tensioner bolt from the under side, pull the belt off and rotate the pulley so you can remove the bolt through the hole in the pulley.

Then remove the last bolt holding it in, on the rear and with the reservoir feed hose still connect, rotate the pump downward to gain access to the rear plate. Remove the bolts and lift off the rear plate, there are fins in the back side which drive the HICAS pumps, removing these fins will prevent the power steering pump from over heating once you've removed the HICAS completely.

Power Steering Pump
Removing the fins from the pump prevents the pump burning out
For my set-up I had the rear rack welded so that it would not move at all, this is important because if you don't lock the rear tie-rods from moving, then your car is going to wobble all over the road and you'll likely crash. If you can't weld, then you'll need to buy a lock bar, or a kit like the Drift works HICAS eliminator assembly. Either approach is effective.
Engine bay solenoid
Starting from the rear at the rack by the differential, unbolt the 2 lines going into the rack, and follow them all the way to the front, removing each part as you go. There's one solenoid near the rear differential, then the lines are clipped to the brake lines, and another large solenoid in the engine bay. Remove all the nuts and bolts, and toss the entire assembly into the bin.
Then you'll notice there is a power steering line that used to go from the solenoid to another line and this line is now not connected to anything. That line must be carefully bent and connected up to the other open line near the front.
Engine Electrical Harness
This will create a loop for the power steering fluid, which still uses the cooler in the grill, so you cannot just block this line off. Once you've connected it in a loop, then the job is done. I know it's hard to see from just looking at the photos, but once you're in there getting your hands dirty it will be obvious which lines need to loop to where, just follow each line to and from the power steering pump and around the cooler. The photo below shows the lines looped together, you can see the grey line bent to shape and fitting in just under the black air piping.
Engine bay fuse box
The last thing you'll need to do is head into the trunk, under the rear parcel shelf there is a control box for the HICAS on the drivers side, remove the 2 bolts securing it and look at the plug harness. Cut the green wire with the white stripe and tape both ends with electrical tape. This disables the HICAS ecu from reporting any problems. Alternatively you could also just remove the light bulb behind the cluster for the HICAS light but thats not as good as an idea because sometimes the HICAS lamp is used by the ECU in conjunction with other lamps to indicate other problems.
4 wheel laser alignment
Lastly, don't drive the car to anywhere until you get an alignment done, after messing with the rear geometry, its far too easy to lose control at speed, so make sure to have the car re-aligned.