Captain_

Hi.
I have a question about rear axle steering ECU. It's easy to believe that this function is controlled by the PASM. But as I so far figured out it has its own control ECU as kindly explained by Porsche. I have been through the schematics but haven't found the location or even the smalest sign of it.
Anybody on the forum knowing about it and if it has its own control box (ECU), and if it has, the physical location of the ECU?

Thanks,

Todd B

RWS is not controlled by the PASM controller. I have DSC controller and I know for a fact it only manages the shocks. Not sure if the PSAM was a typo?

Maybe it’s the PSM controller?

Captain_

Thanks Todd B!! PSAM should be PASM, that was a typo.
That’s what I believe too. PSM Controller Lets see what we find there.
Or as Porsche puts it: Rear-axle steering. Fitted as standard, rear-axle steering combines performance and everyday driveability. An electromechanical adjustment system at each rear wheel enables the steering angle to be adapted based on the current driving situation, steering input and vehicle speed.

If it adapts on the current driving situation it for sure has to have some ECU controlling it.
Let us see if somebody here has dug in to it?

Jean

I believe there is no interaction with any control units.

Captain_

Thanks Jean.
Well that would defently explain the struggle finding its ECU. We know that the rear axle steering system uses both speed and steering input signals.
The question is, from where both left and right rear actuator takes its information? Could it take information from the steering gear controlling front wheel steering which also uses speed signal and produces steering wheel input signal? There is a single part number for both left and right steer actuators, so probably no built in ECUs in them.
Well, somebody probably knows. Just hope they jump on this thread.

sgreer78

Why do you want to know so bad? Just curious?

Captain_

Hi. Firstly I need to know how things I drive/fly work to be able to understand how to use them smart and effectively.
Ive during track days felt that the rear axle does things when sliding all for wheels during maximum attack which I never felt on a car without rear axle steering.
To be able to maximise the use of these modern system cars I just need to understand what it does when and why.
Then an interesting thread showed up here the other day (991.1RS wobble) Where some people indicated that the problem lay in the PASM, those people really seemed to have great experience in these cars.
But I just could not understand how PASM had anything to do with it. May be the PSM controller does? Therefore i started my own research.

JC Lacayo

I was wondering about that myself. Following.

I assume its the car's ECU which monitors speed and steering wheel angle

usrodeo4

I have never seen a blueprint or electrical/mechanical schematic of the entire GT2 RS platform (or other modern P cars with rear wheel steering). But regardless, the rear wheel steering is definitely controlled by computer as it must determine the course of action required according to road speed, steering angle along with longitudinal and latitudinal acceleration to either steer the rear wheels with the front, steer counter or stay straight. I would guess the rear wheels to steer counter to the front wheels at slow speed corners and with the front wheels on higher speed corners and probably also account when the driver is purposely over steering.

Tom@TPC Racing

All the input data is on CAN(Control Area Network). CAN is connected to every control module on the car via two wires.
Read the first sentence from Wiki- https://en.wikipedia.org/wiki/CAN_bus

FrenchToast

If I had to guess I would imagine it's a subset of stability management. Likely taking inputs from the steering angle, wheel speed, yaw sensor, etc. etc. But that's a guess, I don't really know.

If you ask your dealer service desk for the wiring diagram (might be called a current flow diagram) of the actuator, you should be able to trace where the connection originates. The actuator component is fairly simple and I can't imagine it has more than a few wires going to it. The actuator and all the modules will have codes called out in the diagrams (typically a letter with numbers). That said, don't get your hopes up too high. The wires may originate at a sub-module with unknown function.

Agree with you regarding the desire to find out how these systems actually work. But I think the best you can do is a broad understanding. Ask your dealer service desk if there is any documentation on it (sometimes they have self study brochures for employee training).

Captain_

Thanks FrenchToast.
I agree that would be the way to find out in a perfect world. And I guess it would work with any Japanese car company or BMW. But now we talk about PIWIS 3 and thats a different story. Its probably as modern as Microsoft DOS in comparison to rest of the industry's standard.
And boy I was surprised when the dealer service does not even find the connector described in PWIS 3 because PIWIS does not tell you where it is. I Know people well inside and PIWIS 3 is a forgotten priority and sad story. I have had the luck having Porsches head of design MM in my small studio here in Sweden many years ago. So my best chance fining out is probably getting the right connection with Vehicle Mechatronics Specialist in-house knowing how its designed.

Richard.

992 GT3 goes up to 2degress from 1.5 can we amend our 991 settings ?

Richard.

I guess not then !