FORD Fiesta Sync 3 GPS Issues

[G00NERJJ (John Morris)]

Hi All,

I am hoping someone may be able to help me. I recently did the conversion from Sync 1 to Sync 3 in a Fiesta in the UK.
The GPS seems to be wandering off at times and could be a good few miles off from where I actually driving.

I saw this forum page that stated the angle that the APIM is laying can effect the accuracy.

GPS issues after changing APIM physical orientation

I retrofitted a 10p display from an explorer into my Taurus. In my efforts of doing so I had to flip the APIM 180 degrees with the connector facing the cabin. After doing so my GPS is not accurate at all. I thought I remember reading somewhere that there is an asbuilt value for the physical orientation of the APIM. That could have been a sync 4 thing I read though. Anyone have any ideas? Looking at the sync 3 asbuilt I am not seeing anything immediately obvious that could fix this.

Currently I have the Sync 3 APIM located where the original Sync 1 APIM was (under the glove box) laying flat down with the large connector facing straight up. What angle would this be as I am struggling to figure out on what axis this angle would be? Never was good at this sort of thing

Any help would be much appreaciated!

---

SYNC Region: EU

Navigation Variant: Nav

Manufacturer Year: Pre MY20

Install Type: Retrofit

Old SYNC Version: 3.4 23188

New SYNC Version: 3.4 23188

Do you have a error message, if so what is it?
No error message.

Update Method: Official Ford

[F150Chief]

If you keep it that way…

You need to change the values in the APIM asbuilt for the APIM mounting position, since you flipped the APIM.

7D0-07-02 - #### - xxxx - xxxx - Install Angle of APIM for Accelerometer X (Deg)
7D0-07-02 - xxxx - #### - xxxx - Install Angle of APIM for Accelerometer Y (Deg)
7D0-07-02 - xxxx - xxxx - ##xx - Install Angle of APIM for Accelerometer Z (Deg)
7D0-07-03 - ##xx - xxxx - xxxx - Install Angle of APIM for Accelerometer Z (Deg) cont.

Install Angle of APIM for Accelerometer X (Deg)
HEX=DECx0.006+0=Value (degrees)
Install Angle of APIM for Accelerometer Y (Deg)
HEX=DECx0.006+0=Value (degrees)
Install Angle of APIM for Accelerometer Z (Deg)
HEX=DECx0.006+0=Value (degrees)

Is there not a kit that is specifically for this swap to place the APIM on the screen?
Where did you source an APIM asbuilt that you are using? There are specific values that should be populated at 7D0-07-xx and also 7D0-05-xx that are specific to the vehicle model and options. Your Nav depends on these values to be correct to function properly.
Also, is the GPS functioning correctly?
Post your APIM asbuilt here.

As far as the axis question:
The X-axis typically represents horizontal movement, the Y-axis vertical movement, and the Z-axis depth.

[G00NERJJ (John Morris)]

Thanks for the reply!

Yeah the original location of the APIM on these Fiestas over in the US is usually set behind the screen, but I got told by a few people that the APIMs were prone to failure as they are placed directly on sunlight so recommended I placed it under the glove box.

I did get this APIM from a MK8 fiesta which I believe are located behind the dash clocks which would mean the x, y and z axis would be completely off anyway
The AsBuilt I took directly from the APIM itself once it was plugged into my car.
GPS functions at times, but most of the time will start to wander off and then may come back eventually.

I have looked in the diagnostic screen and can see the signal strength of the GPS seems pretty strong and can see the satellites it is connected.

Here is the AsBuilt, hopefully it is attached okay…

Sync 3 Asbuilt_JM.abt (487 Bytes)

[F150Chief]

Asbuilt looks ok.
So, you will need to translate the axis change and try some asbuilt entries. The APIM is now sitting flat on the rear of the unit, I assume. Keep in mind that the axis relationship of the APIM does not relate to the screen, it is the way the gyro is mounted in the APIM. The gyro must be aligned for the GNSS INS navigation to perform properly.

The OEM asbuilt shows…
7D0G7G2 0000 6428 006C (6C is the checksum so ignore it.)
7D0G7G3 00
This equates to…
x = 0000 HEX=DECx0.006+0=Value (degrees) = 0
y = 6428 HEX=DECx0.006+0=Value (degrees) = 25.64
z = 0000 HEX=DECx0.006+0=Value (degrees) = 0

For perspective, my 2015 F-150 with Sync 3 mounted to the screen at a very slight tilt shows these values at…
7D0G7G2 0000 029A 007C (7C is the checksum so ignore it.)
7D0G7G3 00
This equates to…
x = 0000 HEX=DECx0.006+0=Value (degrees) = 0
y = 029A HEX=DECx0.006+0=Value (degrees) = 3.996
z = 0000 HEX=DECx0.006+0=Value (degrees) = 0

My 2019 Nautilus with Sync 3 mounted to the screen at a more laid-back tilt shows these values at…
7D0G7G2 0000 19B7 00B0 (B0 is the checksum so ignore it.)
7D0G7G3 00
This equates to…
x = 0000 HEX=DECx0.006+0=Value (degrees) = 0
y = 19B7 HEX=DECx0.006+0=Value (degrees) = 39.498
z = 0000 HEX=DECx0.006+0=Value (degrees) = 0

Let’s assume that your APIM is in the same orientation but just laid back flat in relation to the vehicle. This would require the value to be changed to reflect the APIM lying horizontal. This does not change the axis definitions, just the values.
I would say that a value of 90 degrees would be what is needed. So, this would be, using the reciprocal of .006…
y = 3A98 HEX=DECx166.666+0=Value (degrees) = 90.00
(90x166.66=14.999.94=HEX 3A98)
(Rounded to 15,000)

Your new value…
7D0G7G2 0000 3A98 00xx (xx is the checksum so ignore it.)

Input this value, let FORScan figure that checksum and write. Make sure the APIM is ignition cycled. See how it works. Remember, the GPS must be working correctly, and clock also.

Here is an informative article on how GNSS INS works.
Introduction to Dead Reckoning | Advanced Navigation

As a footnote, Sync 4 in a 2021+ F-150 is mounted down in the dash, not to the screens. The mounting of the APIM is rotated to the front on the Z axis, therefore required a change to the Z axis to 180 degrees from 0 degrees on 2020 and older Sync 3 vehicles. The X and Y axis’ are straight, or 0 degrees. This mounting configuration is common to the Sync 4 platforms.

Post a pic of the APIM install in your vehicle to determine the proper positioning of the APIM in relation to the axis’.

[G00NERJJ (John Morris)]

Wow I really appreciate the in depth reply mate, thank you!

When you refer to the OEM AsBuilt, is that the OEM of a MK7 Fiesta with Sync 3?

Unfortunately the way I have got it in the car, it is a bit hard to get a decent photo…
But if I was to take the APIM out and place it directly on a table, looking directly over it this is the orientation it is in the car.

With that in mind, would you believe that I would need to set the Z axis to 180 degrees like you described in the sync 4? Basically it is like that but is flat down rather than standing up. Then as you said set the Y axis to 90 degrees so that it is laid flat on the side of the APIM with no connectors (connectors facing up towards windshield)

That article was also an interesting read, I never knew that they would use this to determine positioning. I am guessing the same principle applies for maps on a phone as well?

Regarding the GPS working, I presume it is as from the photos attached you can see that it is connecting to satellites and signal seems strong. The clock however is off by an hour as I don’t think it can determine the GMT/BST time difference? It does state this when I try a GPS time reset. But I manually set the time so that it is correct.

[F150Chief]

@G00NERJJ

When you refer to the OEM AsBuilt, is that the OEM of a MK7 Fiesta with Sync 3?

The one you attached…

@G00NERJJ

With that in mind, would you believe that I would need to set the Z axis to 180 degrees like you described in the sync 4?

Likely, yes. Be prepared for that.

@G00NERJJ

the same principle applies for maps on a phone as well?

It does.

@G00NERJJ

Regarding the GPS working, I presume it is as from the photos attached you can see that it is connecting to satellites and signal seems strong. The clock however is off by an hour as I don’t think it can determine the GMT/BST time difference?

Looks like the GPS itself is working fine. The location accuracy is good.

[G00NERJJ (John Morris)]

@F150Chief

The one you attached…

Oh sorry, for some reason when I did the calculation it came to 153.84 degrees? That’s why I was a bit confused.

I will give it a go setting it to 90 degrees on the y axis and 180 degrees on the z and will let you know how I get on.
Do you think I will need to change any of the other settings like tire circumference and any on 7D0-05-xx?

Thanks again for your help

[F150Chief]

@G00NERJJ

Do you think I will need to change any of the other settings like tire circumference and any on 7D0-05-xx?

Probably not since the vehicles are similar, but you can play with it. You can’t break it…
One thing I was thinking about was the orientation of the APIM with the fins facing up, might be 270 degrees rather than 90 degrees. Keep that in mind.

[G00NERJJ (John Morris)]

@F150Chief

One thing I was thinking about was the orientation of the APIM with the fins facing up, might be 270 degrees rather than 90 degrees.

Yeah I did think that as I was trying to mentally think what orientation it would be, however I tried 180 on z and 270 on y and it seems to have made it even worse

The 2D and 3D accuracy seems to have gotten a lot higher (I am guessing the higher the value, the worse the accuracy?)

I will give it a try with setting the y to 90 degrees once it has stopped raining here to see if it makes any difference.

[G00NERJJ (John Morris)]

I set the y to 90 degrees and it seems to be a lot better with the 2 journeys I did.
It did wander off a couple times but seemed to bring itself back where as before it would stay lost and I would be miles away from where I actually was.

Does the compass work off of the GPS or the APIM accelerometers? Sometimes this seems to be facing in the incorrect direction if I am stationary.

[F150Chief]

Both actually. GPS will tell you where you are, but the decoding unit (APIM) determines the actual way you are facing from GPS data and corrects data when you move.

So right now you have the y axis at 90 degrees and the x and z axis’ at 0 degrees…
So, when you are driving does the map progress in the direction you would expect?
And not jumping around and traveling off severely?
Looking at the NAV screen, there is no GPS alert with the red circle and slash thru it?
I am not familiar enough with a 2016 Fiesta ST, but do the tire circumference settings seem close to you?

I think that the APIM position is very close now, but you might want to check the other settings for accuracy…