Steering module PSCM code: U0401

[G.T.]

I've been trying to understand this code. From what I've read it means the PSCM is receiving implausible data from the PCM/ECM?

I assume the freeze frame is supposed to contain the implausible data? I dont see anything standing out though?

No PCM or ECM codes.

Steering seems ok.

No error notices in cluster.

I've tried clearing it multiple times and it keeps coming back.

I only noticed this checking for faults related to my bouncing window problem, had no inkling at all I'd find an EPAS fault.

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[Texstang]

I had a similar communication code in ForScan, believe it was the 401 code. I thought it was something electrical, maybe a dirty ground, but I cleaned all of them. I replaced the battery not long after (it was 5 years old and getting a little weak), and I've yet to see the code come back. I had verified that my negative and positive connections were tight and had no corrosion beforehand, but it seems like it's very sensitive to battery voltage.

 

[G.T.]

I had a similar communication code in ForScan, believe it was the 401 code. I thought it was something electrical, maybe a dirty ground, but I cleaned all of them. I replaced the battery not long after (it was 5 years old and getting a little weak), and I've yet to see the code come back. I had verified that my negative and positive connections were tight and had no corrosion beforehand, but it seems like it's very sensitive to battery voltage.

Thanks, I think this will be my first step! It worked (so far and for good I hope) for my jumping window problem.

I tried researching a bit more and another thing I saw others do was to check the actual values at the the module to look for any improbable ones to narrow things down.

Looking at the freeze frame, SW_ALIGN _OFFSET: 3276.60° seems sus now at a glance, need to find out what that is I think.

 

[Texstang]

I would see mine set the code about once per day, and I recall that it would occasionally show oddball values like that, but when I viewed the data stream, the values made sense. It was like it would produce weird values prior to starting the car, because the code snapshot was always at 0 mph from what I remember.

I also recall that the code was sometimes accompanied an ABS control module code about battery voltage. I also had a similar ABS code that mentioned invalid data received from the PSCM as well, but don't remember those code numbers.

 

[G.T.]

That's very helpful, will be watching out for things like that when I get the time to work on the car again.

 

[Cobra Jet]

The most common problem for the window issue is that water/moisture gets into the harness connector found inside of the door. You have to remove the door panel, unplug the connector, use compressed air to dry it out, then use dielectric grease to seal out any future water/moisture intrusion.

Here's 2 threads about inop power windows to check; maybe the info helps with diagnosis in your situation:

https://www.mustang6g.com/forums/threads/passenger-window-strange-issue.155949/

https://www.mustang6g.com/forums/threads/drivers-window-will-not-go-back-up-intermittently.151744/

Also check this thread for dancing/bouncing window:
https://www.mustang6g.com/forums/threads/window-reset.52786/page-3#post-1263052

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As for your EPAS issue:
All of the electronics in the S550 are sensitive to battery issues. As mentioned above if the battery is older, most likely it’s a battery issue.

The Ford EPAS unit is also known for water/moisture intrusion issues too. There is a circuit board and also small belt/gearing inside the unit. If the belt is worn and slips that too can cause issues.

Check this thread that has a lot of EPAS/PSCM tech info/links:
https://www.mustang6g.com/forums/threads/s550-epas-pscm-tech-accumulation.160616/

 

[G.T.]

Thanks @Cobra Jet, I did come across your EPAS thread and I just read through the ones you linked on the windows.

I neglected to mention that the battery is close to new and tests fine.

I am actually planning to try and clean the EPAS sockets as done in the thread you linked in your EPAS thread.

I really wasnt expecting the cleaning and dielectric grease to calm my window down this much, especially not seeing anything out of the ordinary at the sockets. I hope I dont jinx it saying that lol!

Hoping doing the same to the EPAS sockets will give positive results too.

 

[Basspro302]

Most of the time freeze frame does not show the issue. That code is triggered when the engine has a fault (misfires, throttle body issue, maf etc.) Its basically telling the abs/tc to shut off because the engine pcm can’t give the request the abs/tc/stabilitrac is sending it like reduce torque wheel slip is too much. It can also be caused by driving hard burnouts, doughnuts etc. If you are not having issues with the car ignore that code for now you will chase your tail.

 

[G.T.]

^ Been doing that but since clearing up some of the more annoying problems its getting moved up to the front of the queue lol!

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