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Discussion Starter #1
Removed all my HICAS gubbins years ago but have just gotten around to removing the HICAS ECU.
Looking at the wiring diagram the HICAS ECU sends a signal to the PAS solenoid located in the fluid feed pipe. Having read many a comment on here about folks experiencing heavy steering after HICAS ECU removal, clearly there is a connection.

First of all, I need to understand how the solenoid operates...i.e is it a simple on/off operation or is it linear? I'm guessing that the solenoid either introduces or removes a flow restriction in the fluid feed line.

I have 2 options......
1. Take the original wire (from HICAS ECU to solenoid) and connect it to an output on my main ECU and provide it with (and this is where understanding the solenoid operation is required) either a fixed voltage to operate (on/off) or a programmed variable voltage (linear) to basically replicate the original output of the HICAS ECU.

2. Remove the solenoid completely and replace with appropriate grub screw to seal. Being a track only car I'm thinking this might be the best option but unsure of just how heavy 'heavy' actually is!!!



So, can anyone with knowledge of the solenoid operation explain to me if it is indeed an fixed (on/off) or variable (linear) voltage that is supplied to it?


TT
 

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Discussion Starter #2
So, need to revisit this again... Having now stripped all wiring out of the car, and in prep for new ECU and PDM I need to have a think about PAS.

I noticed the wires coming from the around the area where the rack and column join and I'm thinking this is the solenoid feed? I'm also thinking that, hooking it up to a PDM output, driven from the ECU should solve the problem and retain speed-sensitive PAS...

I'm thinking that as the ECU can 'see' vehicle speed it can send a message to PDM to send a variable voltage to solenoid thus regulating the steering weight.

Has anyone considered/done a similar thing and does anyone know what the solenoid voltage/speed relationship is??


TT
 

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The voltage is around 5v when stationary and 2v for light. I think the voltage would drop to about 1v at a few mph. This is all from memory.:runaway:
 

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Discussion Starter #4
Thanks Andy...helpful as always..

:thumbsup:

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Discussion Starter #7
No, not looked at it yet TBH. Other things getting in the way....

I reckon i'll just give the solenoid a feed from PDM and increase voltage with speed with the numbers Andy gave above.


TT
 
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