Using Haltech Pnp Platinum To Control Power Steering Solenoid

[HarrisRacing]

I understand from previous replies that the power steering solenoid on the rack acts in such a way as follows:

1) At no voltage applied a plunger is retracted via internal spring and this opens a port that releases pressure from the input of the rack to make steering feel heavy (bleeds off pressure supply). I confirmed this on mine.

2) When applying voltage It worked the plunger at as little as a 9V battery and polarity was not a factor (swapping poles made no difference to operation). I did NOT try lower voltages (sorry). When this is energized, the bleed hole is plugged off and all pressure goes through the rack for very light steering feel.

3) The HICAS computer sends a squar(ish) 123 Hz wave of varying voltages to this solenoid under different modes of operation (found in another thread here). This is basically changing duty cycle of the wave depending on vehicle speed.

at 0 km/hr the solenoid sends roughly 4.4-6V which is approximately 32-47% duty cycle (at 14V).

at 100 km/hr the solenoid sends roughly 1.5-2.2V which is approximately 11-16% duty cycle (at 14V).

4) When removing Hicas parts (or if something in the system is bad) the HICAS computer may disable this function (de-energize the solenoid) and leave the solenoid in constant bleed state (see #1 above).

Here's my plan:

Use a spare Digital Pulsed Output (DPO) from my Haltech PnP Platinum pro (R32) to control the output based on speed of the vehicle. I will need a digital relay for this and use one output from the aux harness.

I added a DPO as an output and called it "Generic Duty Cycle Output" set at 123 HZ in the software and then made a table with 0-200 mph (yes mine is set to mph), and used 50% duty cycle for 0 mph and 0% for 70mph and up and then just linearized the table in between these values. This way I am going to run high duty on low speeds and linearly decrease duty until hitting 0% steering assist at all speeds over 70mph (so when I'm cruising on the highway my solenoid gets a break totally).

Has ANYONE tried this before? I'm going to be getting my car running soon and am currently setting up the Haltech wiring and I/O's. I just wanted to see if anyone has tried this yet.

Thank you,

Patrick

[zebra]

Thats a pretty cool idea. Cant comment on setting it up.

Might have a look at doing similar on my jizz30

[dontfeelcold]

I haven't tried it. What you are doing should work.

The best place to start would be to use an oscilloscope to measure what the solenoid sees (from the factory HICAS ecu) and log it then replicate that in the haltech.

[Duncan]

Agreed it sounds reasonable. I think there is little feedback because everyone just lives with the harder steering, its very usable....

[luke gtr]

Very interested in the results you get.

My steering keeps dripping in and out of heavy/light.

[HarrisRacing]

After getting the car done the steering doesn't feel bad at all. Probably not worth changing tbh. I'll save the pulsed output for something more useful (like fans, etc).

[Sub Boy32]

Mine is running through my Link G4+

Being that I have removed the factory dash and replaced it with a IQ3 Digital Dash, it no longer sends the signal to the ECU to control the speed sense valve on the power steering.

I'm not entirely sure what I/O my tuner has connected it to, but it works just like it used to with the factory dash.