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Diy:disable Hicas, Retain Power Steering. For Free!

blk94r33

By blk94r33,
in Tutorials / DIY / FAQ

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blk94r33 Mentor

blk94r33

Posted
Posted

Before we start, this modification is ENTIRELY AT YOUR OWN RISK and is here purely for the benefit of others, I am in no way claiming it to be safe, reliable or a good idea.

In brief, my HICAS has given me the s**** ever since i bought the car about three years ago, weekly the light came on due to the aftermarket steering wheel the car came with, I pulled the globe out the dash and this worked for months, then the power steering dropped out intermittently, which I got around by re-wiring the HICAS ECU to reset on key-off, and then finally in the last few weeks I hardly had power steering at all. Why not just fix it? Because everyone seems to have trouble eventually and it keeps happening over and over.

If people need I can provide pictures, but the process is relatively simple. I wouldn't recommend doing this if you aren't confident or %100 sure of what you're doing. But this is the cheapest, quickest, most effective fix i've found thus far.

After some digging, I found a way to disable HICAS all-together, and keep the power steering functional. This is for R33 Series 1 NON abs, but may suit others

1. Locate the HICAS ECU under the parcel shelf, unplug the big fat connector at the back.

2. Face the connector towards you as if YOU are the HICAS ECU pins, as this is how the diagram below is read.

3. Observe this diagram: http://www.skylineowners.com/forum/attachment.php?attachmentid=47736&d=1286623689 courtesy of the Skyline owners forum.

Note pins 14 and 5, 14 is 10amp switched power from the ignition, pin 5 is the HICAS ECU signal output to the power steering rack solenoid valve, the ECU uses this wire to give speed proportional power steering.

This next part is up to you, but pins 14 and 5 need to be bridged, personally I recommend cutting and soldering the wires directly together then heat-shrinking to avoid any complications.

FROM MEMORY ONLY, the wire to pin 14 was green with a black trace, and the wire to pin 5 was pink, these two wires need to be used to avoid powering the solenoid with the key off and draining the battery.

This then supplies constant power to the solenoid valve, giving %100 power steering at all speeds (read further down for more information).

4. Leave the HICAS ECU disconnected, as I doubt it will like having 12volt power plumbed back into a signal output, and it's no longer needed anyway.

5. You can now fit a HICAS lock bar without the complication of losing power steering, and disconnect any HICAS related sensors and components with no other side-effects, so long as the wiring from the solenoid valve and switched ignition remains in-tact. I doubt the light will come on, but if it does remove the globe from the dash is the best way around this.

6. Take the car for a drive, but be aware that the steering will be much lighter at high speeds. Be cautious on the first drive as the steering will be much more direct and "twitchier".

Will/can this modification damage my car?

Honestly, i'm yet to find out. I literally did this mod tonight after weeks of frustration and research. The power steering pump could fail, the solenoid valve may burn out, the 10 amps from the ignition fuse may not be enough to run the solenoid long-term, or any other number of nasty things, but once i've driven the car for a while I will report back here if there are any ill-effects.

At the moment the only difference i've noticed on a 10-15 minute test drive is the steering being 15-25% lighter above 80km/h, and also it works on 100% of drives rather than the 10% before.

Can I revert back to HICAS?

Very easily, simply de-bridge the connection between pins 5 and 14, and re-connect the ECU, things will now go back to normal.

Cheers, Josh

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  • 2 weeks later...
blk94r33 Mentor

blk94r33

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Only been on for a week, but done roughly 500km including a few runs at the drags. So far no problems at all, just enjoying my power steering working every time I drive the car!

  • 4 weeks later...
blk94r33 Mentor

blk94r33

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My car doesn't have ABS, and apparently the HICAS ECU is different between ABS and non ABS models, so i'd assume the pin-outs would be different too. They could be the same, but I know that this particular mod works on this exact model GTS/GTST.....

  • 4 weeks later...
blk94r33 Mentor

blk94r33

Posted
  • Author
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Mine wasn't for some reason. If I removed the HICAS ECU the steering went heavy and stayed that way, I assume as there was nothing powering the rack valve and it couldn't get pressure.....

  • 4 weeks later...
Ricky_Bobby Enthusiast

Ricky_Bobby

Posted
Posted

My HICAS lock bar is fitted on my ABS S1 , leaving the Hicas Computer connected in the boot its not my HICAS light that is on, its my ABS light ?

blk94r33 Mentor

blk94r33

Posted
  • Author
Posted

Once i'd figured out how to get the power steering to work without the HICAS ECU I saw no point in leaving it in so it now resides in a box with the rest of the stock parts.... As above the non abs and abs hicas ECU's apparently differ so if the hicas acts up it may upset the abs.

  • 1 month later...
  • 1 month later...
MrMotoX23 Apprentice

MrMotoX23

Posted
Posted

my r33 has a whiny power steering pump and when turning jerks alil do u think doing this will help or is my pump stuffed ? im a new skyline owner and dont know alot about them so any advice would b very helpful :)

  • 7 months later...
paul_psi Collaborator

paul_psi

Posted
Posted

It ended up being the pump i think from memory I changed it and the power steering worked fine again. I'm rebuilding the car again at the moment and putting in a cage so I'll be removing the hicas computer all together so I'll let everyone know if it plays up but I'm also running microtech so I don't think tgere will be a prob

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