R32 non hicas power steering solenoid issues!

[D.phantom]

So I’m having issues with my power steering. the obvious heavy and light and comes on and off randomly now it’s constantly heavy. I’ve read through forums regarding this issue and what I’ve gather is that it’s referring to hicas deletion. That’s the problem mine didn’t come with hicas. 
 

I’ve rebuilt the steering rack, pump, changed the bent hardline on the rack and taken out the solenoid to clean and loosen up the actuator, applied 12v to get it moving. Roughly checked the loom to see if there’s any damage to the loom and nothing.

Now I’m checking the wiring. I’ve tested the wiring to the solenoid and it’s fluctuating between 0.07v to 0.03v. Does anyone know what it’s supposed to be reading? 5v?

Anyone one know how this all works? Is there a fuse in between? What else is it connected to? How does it connect to the speed sensor? A resistor fried in the ecu? Please help. It’s been years

Thanks in advance 

[GTSBoy]

I have no idea what the power steering control module is on a non-HICAS car because I've never seen one. But it is a fair bet that is essentially the same thing as on any other Nissan of the period with variable PS. So, Maximas, that sort of thing.

It will pick up the ECU's speed signal off the "bus" (there's not really a bus - any consumers of the VSS are all just connected to that output on the ECU). The output should (most likely) be a PWM signal to give you an effective average voltage between the minimum and maximum values. You could possibly look at the HICAS part of the R32 manual to see what that range is likely to be (for non-HICAS, as it should be about the same).

[joshuaho96]

8 hours ago, D.phantom said:

So I’m having issues with my power steering. the obvious heavy and light and comes on and off randomly now it’s constantly heavy. I’ve read through forums regarding this issue and what I’ve gather is that it’s referring to hicas deletion. That’s the problem mine didn’t come with hicas. 
 

I’ve rebuilt the steering rack, pump, changed the bent hardline on the rack and taken out the solenoid to clean and loosen up the actuator, applied 12v to get it moving. Roughly checked the loom to see if there’s any damage to the loom and nothing.

Now I’m checking the wiring. I’ve tested the wiring to the solenoid and it’s fluctuating between 0.07v to 0.03v. Does anyone know what it’s supposed to be reading? 5v?

Anyone one know how this all works? Is there a fuse in between? What else is it connected to? How does it connect to the speed sensor? A resistor fried in the ecu? Please help. It’s been years

Thanks in advance 

I don't have the full R32 factory service manual so I don't really know how to help you here but there is an EPS control module that modulates the EPS solenoid, marked C or 28500 in this diagram.

 

The R32 GTR service manual floating around mentions it should be about 4.4-6.6V between the diagnostic connector and solenoid valve at 0 kph, then 1.5-2.2V at 60 mph, it also has the no HICAS equipped variant connector mentioned:

 

Edited May 6, 2024 by joshuaho96

[D.phantom]

Ok thanks for that info. I’ll have another poke around when I have time and update you guys

 

[D.phantom]

Do you know where the EPS module will be located? And also the diagnostic connect located under the dash?

 

[GTSBoy]

2 hours ago, D.phantom said:

Do you know where the EPS module will be located?

A is the HICAS CU.  As far as I know, there are no other modules located at A in a car with HICAS, so it is fair to presume that F is the variable power steer module for non-HICAS cars. Same location, give or take. Makes sense - the wiring loom for the HICAS cars has the speed signal, power, solenoid drive, etc wires all present there - so why move the module and have to upend the wiring loom?

 

Having said the above though, it may be the case that F is further down in the rear guard - it's hard to tell. In which case it may be something else.

2 hours ago, D.phantom said:

And also the diagnostic connect located under the dash?

Yes, it is the multi-pin plug next to the under dash fuse box. Top left corner. Can't miss it. Be very careful though - use insulated probes to poke around in there so  you don't accidentally short 12v to ground or an ECU input etc etc.

Edited May 6, 2024 by GTSBoy

[D.phantom]

Ok thanks again

[joshuaho96]

1 hour ago, GTSBoy said:

A is the HICAS CU.  As far as I know, there are no other modules located at A in a car with HICAS, so it is fair to presume that F is the variable power steer module for non-HICAS cars. Same location, give or take. Makes sense - the wiring loom for the HICAS cars has the speed signal, power, solenoid drive, etc wires all present there - so why move the module and have to upend the wiring loom?

 

Having said the above though, it may be the case that F is further down in the rear guard - it's hard to tell. In which case it may be something else.

Yes, it is the multi-pin plug next to the under dash fuse box. Top left corner. Can't miss it. Be very careful though - use insulated probes to poke around in there so  you don't accidentally short 12v to ground or an ECU input etc etc.

I don't know if this is accurate. The EPC places the EPS control unit somewhere in the engine bay or somewhere in the interior near the firewall, presumably because the things it's controlling mostly live up in the front of the car unlike HICAS which has a whole steering rack on the rear axle to handle.

@D.phantom The R32 GTR manual actually has more than I give credit for talking about the non-HICAS cars:

You can probe the pins on the diagnostic connector directly to read the EPS solenoid voltage as far as I can tell following the flow chart.

Edited May 6, 2024 by joshuaho96

[GTSBoy]

4 hours ago, joshuaho96 said:

The R32 GTR manual actually has more than I give credit for talking about the non-HICAS cars:

Nah. I reckon that that is the HICAS CU. Just the large plug, PS specific and other I/O. I can't see that there'd be a need/want for the (non-HICAS) PS CU to be watching any of those inputs other than the speed sensor.

[joshuaho96]

10 hours ago, GTSBoy said:

Nah. I reckon that that is the HICAS CU. Just the large plug, PS specific and other I/O. I can't see that there'd be a need/want for the (non-HICAS) PS CU to be watching any of those inputs other than the speed sensor.

HICAS has a much more complicated circuit diagram, for some reason the R32 GTR service manual discusses both. The HICAS module has proper 2 way communication over consult, the "EPS control unit" doesn't have any of that and only exposes a raw analog voltage for the EPS solenoid valve. It's ultimately mostly about speed sensitive steering but the non-HICAS unit also looks at the neutral switch/brake/clutch switch to adjust how it provides assist.

[GTSBoy]

40 minutes ago, joshuaho96 said:

the "EPS control unit" doesn't have any of that and only exposes a raw analog voltage for the EPS solenoid valve. It's ultimately mostly about speed sensitive steering but the non-HICAS unit also looks at the neutral switch/brake/clutch switch to adjust how it provides assist.

Yeah, alright, I take it back. I hadn't bothered to compare the terminal numbers - they're not the same. I was working on the presumption that it was the "small plug" half of the HICAS CU because it has the same plug as the small plug on the HICAS CU. And...the drawing says "Refer to Super HICAS system circuit diagram" which seemed to place it firmly in the world of HICAS, not non-HICAS.