My Power Steerings Gone After Installing Hicas Lock Bar

[heller44]

From initial reading I don't think the DPA will work in this situation. It looks for a duty cycle input and modifies it to give a duty cycle output.

This would work well if we were keeping the hicas module with the power steering solenoid output and just modifying the 'weight' of the steering from standard.

What we would be looking for is a frequency input to a duty cycle output. The input from the speedo will be a sort-of sino-square wave.

[noone]

About to fit a hicas lock bar now (thanks salad) so keen to hear how this goes, with the digital pulse adjuster. SydneyKid or anyone else do you know what voltage the speedo outputs to the ecu for various speeds ?

[someonestolecc]

Jaycar have a kit called a Digital Pulse Adjuster (much the same as the IEBC). It can read the pulse signal from the speedo input to the ECU. You can then program in your own output to the bypass solenoid. For example, up to 20 kph you might want 1hz of pulsation (bypass) so that there is lots of power steering assistance. At say 50 kph you might want 5hz, so that there is less assistance. Then at say 100 kph you might want to turn the power assistance pretty much off. The DPA has 128 load points, so you could vary the power assistance every 2 or 3 kph if you wanted. Or just step it down every 10kph or so. Basically you would get to choose your own power assistance curve.

Keep in mind that I have guessed the 1hz, 5hz etc, you would have to test it yourself in the real world and determine what works. But that is pretty easy, same as tuning the IEBC for boost, you just fiddle with the bypass map until you get the curve you want. Have a read of the DFA & IEBC thread in the Stagea section for some details on the kits.

cheers

Thanks SKid. Familiar with the theory - just wondering if you have the exact nissan specs I'd only be interested in replicating that, not sure if I would like my own values - wouldn't it be a bit disconcerting ??

[noone]

This digital pulse adjuster, the jaycar one is it a smaller lighter thing than the hicas computer?

would be easier to use an existing product than build from scratch.

That said by pulling only the smaller plug I lost the HICAS error light still seem to have power steering and even get the hicas light come up for low power steering fluid

[dangerous_daveo]

So after reading all that, I should really put my hicas computer back in my cefiro...?

[Sydneykid]

From initial reading I don't think the DPA will work in this situation. It looks for a duty cycle input and modifies it to give a duty cycle output.

This would work well if we were keeping the hicas module with the power steering solenoid output and just modifying the 'weight' of the steering from standard.

What we would be looking for is a frequency input to a duty cycle output. The input from the speedo will be a sort-of sino-square wave.

Wouldn't that be the same as the injector pulsing used as input for the IEBC?

cheers

[heller44]

Just waiting for the first coffee of the morning to kick in,.. i really do like haveing weekends off.

The injector input used for the IEBC is a duty cycle, thats how the IEBC calulates the load that the engine is under. ie duty cycle in, modified duty cycle out to boost solenoid.

The DPA is basically the same under the skin.

We can't use anything other than a speed referenced input, and the only one available is the speedo feed to both the ecu and power steering module. This signal is a frequency ramp, with a constant duty cycle, therefore the IEBC and DPA won't have a varying signal, it will just sit there. The duty cycle of the speedo output will be the same at 10kmph as it is at 100kmph. The time off and on ratio of the signal won't change, the time will but from my understanding of how the units operate the duty cycle ratio is what it is concerned about.

I think I need another coffee.

James.

[noone]

I think I need a coffee after reading that

maybe I will just have a beer instead and forget about it hicas ecu aint that heavy

[heller44]

H'ok, it has taken me a while to get back to this, but I have finally got some pictures for you folks.

First one is at 0 km/h, second one is at ~40 km/h. You can see the decrease in duty cycle as the speed increases.

The waveform isn't a nice clean square as the diagnostics pickup is across the solenoid and the coil is acting on the square wave to bugger it up, but the area under the curve is what is the most important, cos thats where the average power is calulated from.

0kmph

40kmph

You can also see in the pictures that the frequency of the waveform hasn't changed, still 123Hz.

James.

[dontfeelcold]

How much current does the solenoid pull and what is the max voltage it operates at?

This microcontroller I have should be able to control the solenoid. Its just a matter of making sure I use a mosfet that can handle the ampereage and voltage. I can also use a variable resistor to vary the amount of power assistance at different speeds.

Edited April 3, 2007 by dontfeelcold

[heller44]

Manual says solenoid is 4-6Ω so thats what 2-3 amps approx. wire is fairly small so it won't be much more..

[dontfeelcold]

I will have a look for a suitable mosfet and see what happens.

[heller44]

Probably an IRF520. Cheap and you can even get them at dse. 8A rated.

[heller44]

What you want is a microcontroller that has an F/V front input, then an PWM output driving the mosfet. Dead easy. Pity that i never learnt how to program PIC's or Micro's. What micro were you looking at running?

[dontfeelcold]

I have a PICAXE 28X. Its a package made for learning microcontrollers as it has alot of extra functions already built into it. It comes with a disc with all of the commands and tutorials of how to use them. It also has tutorials for interfacing circuits and there is one that shows you how to use a solenoid so I though I would have a go. It recommends using the IRF530, which is can handle up to 14 amps.

By F/V do you mean frequency/voltage? Yes it has PWM out and is what it recommends to use.

PIC programming is easy, working out the logic for the program is the difficult yet fun part.

Providing I get it working, who is going to offer the doner car? As my car won't be running for a long time.

[heller44]

Sounds like a plan. The IRF530 would be better than the 520, lower Rds(on) so less heat on the mosfet itself. Only prob is most people wouldn't be able to get one easily, dse stock irf 520, but not 530. For that you need rs or farnell or equiv.

F/V input.. reading in a frequency input and being able to work on that directly, otherwise you need to use a dedicated F/V circuit to convert it into an analogue voltage range for the pic to use.

The other way to do it it use the pulse counting input on the pic and count how many pulses per amount of clocks, generate your own digital frequency number from that information and use that to affect the PWM wave output.

Have fun.

James.

Edited April 3, 2007 by heller44

[Nathan_G1]

heaps of people always get hicas problems.......NS.com is probly the worst place to look for directions LOL

someone make a sticky of disconnecting hicas (unless ive always browzed past it) and tell people the easiest way, the hardest way.........experiences blah blah

personally i found it easy to take off and replace with a lock bar, i removed the plumbing to the first reserviour tank and then plumbed up the ends so that the tank still circulated but hicas was gone.......didnt touch power steering pump or any of that, just did it the safest and easiest way

[dontfeelcold]

Got a couple of IRF520's (good enough for now and a spare incase I melt one). I will pull the sollenoid off tonight and start playing.

Edited April 5, 2007 by dontfeelcold

[mr_rbman]

heaps of people always get hicas problems.......NS.com is probly the worst place to look for directions LOL

someone make a sticky of disconnecting hicas (unless ive always browzed past it) and tell people the easiest way, the hardest way.........experiences blah blah

personally i found it easy to take off and replace with a lock bar, i removed the plumbing to the first reserviour tank and then plumbed up the ends so that the tank still circulated but hicas was gone.......didnt touch power steering pump or any of that, just did it the safest and easiest way

Salad has done a very good tutorial on removing the hicas aswell as a couple of other people. Also removing hicas on a 33 is a lot easier than a 32!

[T04GTR]

yes they have variable steering. speed dependeant. ranging from 6 volts at no speed down to 2 volts or there abouts at 100k. unpluging the hicas computer means no voltage so no increase in rack presure and heavy steering.