Steering Angle Sensor (SAS) Angle Reset/Calibration - Questions, Questions

[dspa]

Hi All,
I wasn't sure what sub-forum to post in, so hopefully this is a good place to start.
Since I bought my truck, I've had trouble with the steering wheel being perfectly straight. It wasn't terrible, but always noticeable (especially to Mr. OCD, here). It's always been off slightly either right or left. I've had it aligned twice at the dealer (2nd time because they made the steering wheel crooked the other way from when I took it in) and a 3rd time again, today, at what is considered the best alignment shop in Albuquerque.
After the alignment today, although it appears they got the tie rod adjustments pretty much perfect for straightening the steering wheel, I noticed a pull to the right at freeway speeds. It's not intense but it's there. Steering weight is also heavier to one side. I suspected the Drift/Pull Compensation so called the alignment shop to report the issue. Told them I'd drive it a bit more and report back again. Drove the truck some more and noticed the issue persisted on multiple roads/road crowns. Called the alignment shop again and asked them the question I had ASSumed I knew the answer to: "Did you reset the Steering Angle Sensor?" "No, we were unable to do that. Our computer couldn't access that function on your truck because it's too new." This is after they told me at drop-off that SAS reset was part of the alignment procedure, aligned the truck for me, and sent me on my merry way, never thinking/caring to tell me they couldn't reset the SAS. You know what they say happens when you assume.
So anyway, I started poking around on how to reset the SAS. I found the readout in FORscan that shows the SAS reading (in the ABS module under live monitoring, although curiously it's reported as a calculated value). However, I cannot for the life of me find a way to re-zero the SAS. I realize I could just disable Drift/Pull Compensation but that won't do anything for the other systems that rely upon the SAS being accurate. I've attached a picture below of what my steering wheel looks like when the SAS readout is 0.0.
At this point I don't think the dealer reset the SAS angle after the first 2 alignments I had, either. It is so far out of whack compared to the relatively small off-centeredness of my steering wheel before realignment that I can't imagine it was ever accurate.
All I want to do is reset it to 0.0 when the steering wheel is straight. Does anyone know how to do that, either with FORscan or another tool? I really don't want to take it to the dealer. I don't trust them, and they'll way over charge me for it. I'm willing to buy a tool for this as I'll probably need to do it again at some point in the future.
And yes, I looked, not just in the forum, but all over the web, for instructions on how to do this.
Thanks in advance to anyone who chimes in here with wise words (or snarkiness - I enjoy that too).
Dustin

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[Jesse-Infotainment]

Looks like you would need FDRS. If it isnt in the Wrench section of Forscan. Toe adjustment seems to be something that needs to be done while on the Alignment rack

 

[dspa]

Hi Jesse,
Thanks for this. I was afraid that was going to be the case. Seems strange that FORscan would not have this function. I wonder if they’re working on it.
That SECM doesn’t even appear in FORscan when I connect. I found a device from a third party company that claims to be able to access the SECM and perform the reset. I may give that a try.

 

[dspa]

I ordered a Thinkdiag 2. Supposedly it can perform the SAS reset. I’ll report back here with my results.

 

[dspa]

Well, that didn’t work. Bummer. At this point, I’m thinking I will just disable pull drift compensation for three or four years to give the indy mechanics time to get the ability to reset the SAS with their Hunter equipment. Or maybe the FORscan devs will figure it out.

 

[dspa]

Here's a short video I made showing how far off my steering wheel is from center compared to the FORscan STR_ANG_C readout: Video link (YouTube)

I can only think the truck must have come this way from the factory and that the dealer who did the first two alignments didn't re-zero it afterward. It's about twice as far off as the steering wheel centering that I was trying to correct with the alignments ever was.

PS: If someone else with FORscan would be willing to tell me if their SWA parameter also reads -780.10, I'd be interested to hear that. As of now it's got me a little curious.

 

[powerboatr]

have you tried this?
i know it will sound really weird. but turn off truck, then turn steering wheel a few turns to get wheels pointed left or right about half travel.

then start truck and drive straight, you will have to pull wheel to get you straight, and it will sort of fight you with some resistance in the steering wheel, like the power steering is OFF( or a truck with no pwr steering) but after 1/2 mile or so the truck will figure out the steering is back to center.
i found out about this in my 16 expedition one day when i had turned the wheels left when truck was off, it drive harsh for about 1/2 mile, even though i could steer and drive straight then all the sudden it was normal and truck drove straight.
it costs you nothing

and our trucks have a built in "auto trim of sorts" to allow you to not have to hold wheel so hard in cross winds or crowned roads the system is supposed to pick up your inputs and then hold the wheel while giving you a less tight grip.

 

[dspa]

Hi powerboatr,

Thanks for the idea. What you are describing sounds like pull/drift compensation. I turned that off in FORscan tonight and will be taking the truck out on the freeway for a while tomorrow to see if it helps with the pull. Even if it works, it still leaves the problem of the truck thinking the steering wheel is turned almost 5 degrees to the right when it is tracking straight. What other systems this may affect, I can’t say for sure, but at the very least, I imagine it has an effect on the ABS, traction control and the adaptive headlights. I just don’t know. I have a bad feeling I’m going to end up back at the dealer.

 

[dspa]

Alright, updates...

During the night I heard back from the manufacturer of the Thinkdiag 2, ThinkCar, and also from the FORscan developer.

The ThinkCar folks I'm still going back and forth with. I'm probably going to end up returning it. Not only does it not seem to want to connect with my truck, but the software is not very intuitive and constantly asks for reviews. They are trying to help, so I'll give them a chance for now. I've got time with Amazon to do the return, yet.

The FORscan developer actually sent me a test build with the SAS Calibration function enabled. It's in the ABS module. This makes sense as that's the only place I found a reliable readout for steering angle. However, the calibration/reset process failed out before it could initiate. I emailed him back and sent him my debug logs and am waiting to hear from him again. Interestingly, he did tell me there is no SAS reset function in FDRS for the 2021+ trucks. If that's the case, it's beyond me how the truck is supposed to know that the steering wheel is centered. Maybe it's an adaptive process sort of like powerboatr described.

Anyhow, I drove the truck about 50 miles today on a mix of freeways, highways, and surface streets with the Pull/Drift Compensation turned off. I really liked it. The pull to the right is gone. The truck also behaves like other vehicles I've driven in my life. No weird dead feeling at center... I just steer, compensating on my own for road crown. Feels natural. I may turn it back on eventually... I may not. Before I do, I really want to figure out why the Calculated Steering Angle is reading so far off. Maybe I'm overthinking it, but it just doesn't seem like it should be that way.

 

[dspa]

Heard back from FORscan and ThinkCar during the night.

FORscan: "Sorry, but according to the debug information provided, the SAS calibration function is not supported by your ABS module."

ThinkCar (Paraphrased): Try using an Android phone instead of an iPhone, or return the device for a refund.

I sent an email to a reputable indy Ford service shop in Chicago to get his thoughts. Maybe he'll answer, maybe he won't. I wouldn't blame him if he doesn't. But I hope he does.

 

[Jesse-Infotainment]

Adaptive Steering System

The SECM controls the functions of the adaptive steering system and communicates with other modules through the SASM over the HS-CAN2 . The SECM and the SASM communicate over a private CAN .

To activate, the SECM requires the following:

• Battery voltage
• Ignition voltage
• Communication with other modules over the HS-CAN2
• Power pack status message from the PCM

The SECM uses a motor to turn a toothed hub connected to the steering shaft to add or subtract incremental turns to the driver steering shaft input. At low speeds the same steering input from the driver delivers more front wheel angle, providing more low-speed agility. Low speed maneuvers require significantly less steering wheel rotation. At high speeds, straight line driving precision is increased, providing the driver with an improved highway driving experience and feel during moderate-to-high-speed cornering.

As the driver turns the steering wheel, the SASM detects the speed and direction of the steering wheel rotation and transmits this information to the SECM over a private CAN . The SECM responds by activating the motor in the appropriate direction and speed to change the turning ratio of the front wheels, thereby reducing the necessary number of steering wheel turns required by the driver.

The SECM is self-monitoring and is capable of setting and storing Diagnostic Trouble Codes (DTCs). Depending on the nature of the DTC set, the SECM may send a request to the IPC to illuminate the adaptive steering system warning indicator and display a message in the message center, alerting the driver of a potential adaptive steering system concern. The warning message is sent over the HS-CAN2 to the GWM where it is converted to a HS-CAN3 message and sent to the IPC over the HS-CAN3 .



Buy a mongoose and get FDRS so you can get it handled. Take it back to the alignment shop and let them use it to do the alignment. That is how the alignment is supposed to be don e in the trucks witht he SECM.

 

[dspa]

Hi Jesse,

Wow, that's an info-packed post and a good read!

My truck, however, doesn't have adaptive steering or an SECM.

I got a reply from the indy mechanic in Chicago. We might be on to something, but I want to wait on his reply to my reply before I get any more in the weeds, here.

Friggin' Ford completely burying what used to be a simple function to drive people to dealership service departments makes me miss my 2001 Ram Cummins more and more. Centering the steering on that thing just took a couple of wrenches and a few minutes of my time. And no computers!

 

[dspa]

Time for me to eat some crow. Here goes...

It does not appear my truck requires a steering angle sensor calibration after an alignment. Trucks WITH adaptive steering have a module called the SECM (Steering Effort Control Module) that requires calibration, but trucks without can just be toed and sent on their way.

After hooking up to FORscan, Thinkdiag, and my mechanic friend's very expensive Autel MaxiSys, it is obvious my truck has neither a SECM (makes sense since I don't have adaptive steering) nor an SASM (and therefore no SASM to calibrate).

Regarding the readout in my YouTube video... it does appear that this CALCULATED steering angle in the ABS module is indeed just that: a calculated value. From the service manual:

ABS Module
The ABS module is attached directly to the HCU and is not available separately for service. The ABS
module is the ECU for all of the ABS and stability control systems, parking brake and electric brake
boost. The ABS module monitors all sensor inputs and all CAN messages relating to ABS , stability
control and driver input, then directly controls the solenoid valves and the hydraulic pump motor in the HCU . When an ABS , EBB or stability control system fault has been corrected or a new component has been installed, the ABS module must be programmed or calibrated using a diagnostic scan tool. The calibration procedure is required for the stability control sensors to learn the zero-position of the vehicle. The calibration procedure requires the vehicle to be on a level surface and not moving. The calibration procedure (IVD Initialization) is carried out using a diagnostic scan tool. The vehicle must also be driven over 20 km/h (12 mph) for at least 1 minute on a fairly straight road which allows the ABS module to find the steering angle center.

Powerboatr, I think your advice was the most sound I received in this thread, which basically amounts to "drive the truck for a while and it will figure itself out." Additionally, Jesse's post above will prove extremely relevant and helpful to any of you who have a truck WITH adaptive steering.

I also struckthrough (but left for posterity) my comment about Ford burying the procedure in my above post. On the contrary, they've actually made it very easy to get an alignment done by keeping a SAS reset out of the equation!

 

[HammaMan]

There's a couple degrees of adjustment capable within the wheel itself by loosening the bolt. It took me 3 tries to get it OCD perfect post raptor wheel install.

 

[dspa]

There's a couple degrees of adjustment capable within the wheel itself by loosening the bolt. It took me 3 tries to get it OCD perfect post raptor wheel install.

I actually tried this a few months ago when I added back the heated steering that Ford felt it necessary to remove during the truck's production. Couldn't get it enough in one direction to straighten it. The alignment shop I went to a few weeks back did a good enough job that my OCD is (mostly) appeased. I'm also not uncomfortable doing micro adjustments on tie rods if needs be.

I"m just happy to know there's no SAS calibration/reset required after an alignment. Makes things a lot easier, now and in the future.

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