My Power Steerings Gone After Installing Hicas Lock Bar

[mr_rbman]

hey guys

well i just finished locking my hi-cas but my power steering has basically dissappeared and is now very heavy to drive. I used this method http://www.nissansilvia.com/forums/locking...13-t185697.html down to every last step (this was definitely the easiest and best explaination of what to do out of the 3 tutorials i've seen) the only thing i did different was i also pulled out the hicas computer under the parcel shelf in the boot which it doesn't say to do but surely that couldn't be part of my problem now that i have no 4ws?

And yes before anyone asks there is the right amount of power steering fluid in the car, i topped it up!

anyone got any ideas?

Also the power steering pump i think was making a wierd noise for about 2 minutes when i started the car for the first time but i presume thats because the power steering fluid had to go through the system again?

[mr_rbman]

just found out that us 32 guys need to leave the hicas computer in the car, i'll go put it back in and see how i go!

[GTS-t VSPEC]

You still need the HICAS computer in, as it feeds back a signal to the power steering pump.

[GTS-t VSPEC]

This only seems to apply to the R32's, the rest seem to work without it

[mr_rbman]

just hooked it up and she's all sweet, now i just got to get a wheel alignment this week!

[GTS-t VSPEC]

Cool, easy fix

[salad]

My guide was better before the stupid NS mods moved the pics out of order...

Edited March 12, 2007 by salad

[Sydneykid]

There are no electrical connections to the power steering pump that I can see.

The only electrical connection seems to be to the solenoid on the power steering rack.

So, why can’t you remove the HICAS computer?

Is the power steering speed sensitive?

Does the HICAS computer vary the amount of power assist by varying the amount of steering rack hydraulic assistance bypass using the solenoid?

Does the HICAS computer know the speed (via a link to the ECU)?

Does the HICAS computer open/close the solenoid depending on that speed?

Is it a simple open or close? Or does the solenoid have various amounts of bypass?

Say 0% at <20kph, 30% at 60 kph, 50% at 80 kph and 100% at >100 kph?

Is there a definitive NISSAN publication on R32/33/34 variable assist power steering?

For some time I have been contemplating removing the HICAS computer from the R32GTST. I was considering using one of the Datalogit outputs to control the power steering assist. But I need to know the solenoid parameters.

cheers

[heller44]

There are no electrical connections to the power steering pump that I can see.

The only electrical connection seems to be to the solenoid on the power steering rack.

So, why can’t you remove the HICAS computer?

Is the power steering speed sensitive?

Does the HICAS computer vary the amount of power assist by varying the amount of steering rack hydraulic assistance bypass using the solenoid?

Does the HICAS computer know the speed (via a link to the ECU)?

Does the HICAS computer open/close the solenoid depending on that speed?

Is it a simple open or close? Or does the solenoid have various amounts of bypass?

Say 0% at <20kph, 30% at 60 kph, 50% at 80 kph and 100% at >100 kph?

Is there a definitive NISSAN publication on R32/33/34 variable assist power steering?

For some time I have been contemplating removing the HICAS computer from the R32GTST. I was considering using one of the Datalogit outputs to control the power steering assist. But I need to know the solenoid parameters.

cheers

{This is from memory out of the r32 gtr service manual..}

The variable assist is done on the solenoid on the steering rack.

The varying voltage to the solenoid comes from the hicas computer. There is a speed signal that goes from the speedo cluster to the hicas computer. The force ramp is not quite linear but can be approximated as increasing with speed, graph in manual.

I am fuzzy on wether the speed signal goes through the ecu before going to the hicas module, just sure on the origin and end point.

As my copy of the manual is at home I can't confirm or deny, But I have been studying this section recently because mine has power assist issues at the moment. Car has been converted from auto to manual at some stage and wiring is all up the duff.

If any of this helps at all...

James.

*edit for v vs f.. f increases. Fairly sure v decreases.

Edited March 13, 2007 by heller44

[Sydneykid]

{This is from memory out of the r32 gtr service manual..}

The variable assist is done on the solenoid on the steering rack.

The varying voltage to the solenoid comes from the hicas computer. There is a speed signal that goes from the speedo cluster to the hicas computer. The force ramp is not quite linear but can be approximated as increasing with speed, graph in manual.

I am fuzzy on wether the speed signal goes through the ecu before going to the hicas module, just sure on the origin and end point.

As my copy of the manual is at home I can't confirm or deny, But I have been studying this section recently because mine has power assist issues at the moment. Car has been converted from auto to manual at some stage and wiring is all up the duff.

If any of this helps at all...

James.

*edit for v vs f.. f increases. Fairly sure v decreases.

Thanks James.

The R32 speedo cable (mechanical) goes to the speedo, then electronic to the ECU.

Solenoid voltage......maybe duty cycle? Using the variation in duty cycle to provide different levels of assist.

Time to stick a meter on the solenoid, jack the rear wheels up, try various kph and see what happens to the solenoid.

If solenoid pulsing is the case then I could use a Jaycar digital pulse controller (similar circuit to IEBC) with the speedo pulse as the input. But I might as well leave the HICAS computer in, they weigh about the same. I have already pulled the warning light bulb, so no gain there. The only thing I could do is program my own levels of power assist.

cheers

[mr_rbman]

all i know is that i dis connected the hicas computer and lost my power steering then i re connected it and my power steering was back so i'm leaving it!

[heller44]

No worries.

I'll look at the manual when i get home. There is a fairly comprehensive writeup on the variable assist in there.

mr_rbman: thats about what you'll have to do to keep it. Others I have seen trying to strap the solenoid have just had either very heavy or very light steering. Just letting the system do its job is the best way.

I'm currently missing a clutch switch input and neutral switch input to the hicas computer.. without those two I can't even get into the diagnostics mode... But hey, I might be chasing wiring.. but at least I gained a 26.

James.

Edited March 13, 2007 by heller44

[salad]

An alternative to removing the bulb from the dash is cutting one wire on the smaller of the two plugs into the hicas computer. It is green with white trace line, and is in the bottom left corner. I found this easier than removing the dash to pull the bulb out and the light will still come on if you have low power steering fluid.

You can also just leave the smaller plug out and it has the same effect, I didn't notice anything else going wrong when I did that.

[heller44]

Voltage:

0 km/h (0 MPH) : Approx. 4.4 - 6.6V

100 km/h (62MPH) : Approx. 1.5 - 2.2V

This is the value range that it should be delivered to the solenoid. According to the manual.

Still unsure if it a pwm signal or a variable dc. IF it is a straight solenoid function, it would be a pwm, which a digital meter would just be reading the rms of the pulses.

The speed signal from the speedo gauge goes to the ecu and to the power steering control unit (which is housed in the hicas module, thats why it has a seperate smaller plug. ie. what salad said above ^ ).

Thats an idea.. Might do some diagnosis this weekend, bring the cro home and have a look-see..

James.

Edited March 14, 2007 by heller44

[heller44]

The smaller plug by itself on non-hicas cars contains all the wiring for the power steering control.

The smaller plug on the hicas equipped cars has the hicas solenoid outputs, hicas failsafe output and hicas warning light, so it could be left unplugged after the hicas unit is locked.

The larger plug contains all the inputs and the power steering output.

The wiring diagrams show the same plug shape used for hicas and non-hicas, just wiring changed.

James.

[mr_rbman]

i just cut the wire like salad said to stop the light coming on!

Edited March 13, 2007 by mr_rbman

[Sydneykid]

Voltage:

0 km/h (0 MPH) : Approx. 4.4 - 66V

100 km/h (62MPH) : Approx. 1.5 - 2.2V

This is the value range that it should be delivered to the solenoid. According to the manual.

Still unsure if it a pwm signal or a variable dc. IF it is a straight solenoid function, it would be a pwm, which a digital meter would just be reading the rms of the pulses.

The speed signal from the speedo gauge goes to the ecu and to the power steering control unit (which is housed in the hicas module, thats why it has a seperate smaller plug. ie. what salad said above ^ ).

Thats an idea.. Might do some diagnosis this weekend, bring the cro home and have a look-see..

James.

Hi James, thanks for that info. Would I be right in assuming 6.6 volts (not 66 volts)?

From memory (always risky) doesn't 14 volts DC cycled at 20hz = 4 volts?

So it is most likely a pulsing solenoid, something like lower voltage = lower frequency = higher bypass

cheers

[heller44]

Sorry about that. Finger fault. 4.4v-6.6v

The voltage measured could be a function of an decrease in the frequency, or an decrease in duty cycle, or an decrease in voltage. If I had to bet, I'd say an decrease in duty cycle would be the more likely, easier to pwm the signal than try and vary the frequency.

[someonestolecc]

I was toying with the idea of a variable resistor but then that would be static, I'm also not convinced it's a safe thing to do.

I'm scared of just putting a backing plate on because the Nissan part is really flatly machined, I also don't want super light steering.

SKid - was the way you were planning to do it based around replicating the stock HICAS computer's adjustment based on speed?

[Sydneykid]

I was toying with the idea of a variable resistor but then that would be static, I'm also not convinced it's a safe thing to do.

I'm scared of just putting a backing plate on because the Nissan part is really flatly machined, I also don't want super light steering.

SKid - was the way you were planning to do it based around replicating the stock HICAS computer's adjustment based on speed?

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