openinverter forum

Does anyone know how it works and how it figures out drivers intent to go left/right?

Is that sent from the "squib"? That part seemed to have a steering wheel position sensor in it.

Ours is connected but doesn't do anything, so I suspect it doesn't realise the wheel is being turned, so now wondering if someone has reverse engineered/debugged it a bit to figure out how it get's its signal.

I think I can answer my own question:

I had a look this morning at the workshop manual STC - "STEERING CONTROL SYSTEM".

STC-14 gives a list of priorities:
(1) U1000 - CAN Comm error
(2) C1609 - CAN Vehicle Speed
(3) C1601 - Battery Voltage
(4) all else

Further there is C1604 for the Torque sensor, which is part of the steering column according to STC and ST manual.

So I suspect the power steering unit needs to get a heartbeat CAN message with the vehicle speed information to be happy.
Has anyone generated those before? From the manual it appears that is normally generated in the ABS actuators, or at least with data from them.

Maybe replacing it with a manual pump is the easier way, although it would be neat to get it working.

We ended up fitting the TRW pump from an Astra H that everyone seems to be using as I don't have time to dig into this further right now.

I was wondering about the Leaf power steering unit as I also have one but will probably do the same as you.

I'm taking mine a step further and looking at swapping out the TRW for the Corsa B/C EPAS column. I imagine it operates the same as the Leaf or Prius steering column units. You can also get an aftermarket pot you fit to the dash to allow you dial up or down the responsiveness.
https://www.ebay.co.uk/itm/Corsa-B-C-Ki ... 2463712424
It's used everywhere in the rallying world, relatively straight forward fit and response is instant. It's the one thing that bugged me with the TRW was the constant whine and the delay when you jump into the car of 10 seconds before you have full pressure.
Just picked it up the epas this week but will be putting up my results when I get to swapping.

Sweet!
Look forward to seeing your progress, it might even use less power.