GPS inaccuracy, wheel tick frequency and tire circumference hex

I was hoping to make a few changes as I’m having issues with the accuracy of the GPS when using the Nav and CarPlay. sometimes when I turn it will show me in a field or incorrect location. The longer I drive the worse it is. My original post is here of the sync 2 to sync 3. This is in a 2011 Lincoln MKX and the new sync 3 was from a 2017 MKX

I would like to make changes to the following lines
7D0-03-01 *xxx xxxx xxxx Wheel Tick Frequency
0=20ms (Default Sync 3)
2=40ms (Default Sync 2)
I currently have line 7D0-03-01 set to 0 I’m not sure if this should be changed

The other thing I wasn’t sure about was 7D0-07-03. Currently it looks like 0056 5683 0010 this is from the original 2017 MKX as built. If I was to change the wheel ticks to revolution front and rear, I’m really not understanding the formula same thing with tire circumference. I was looking for some examples of the formula but had no luck. I was hoping someone could help me?
The tires are 265/40/22 that is a circumference of 95.3” or 242.15cm
so would the value for xxxx-xx**-xxxx be 95?
HEX=DECx1+100=Value (cm) x0.393701=Value (in)
(242.14 x 0.393701 = 95)

7D0-07-03 xx xxxx xxxx Install Angle of APIM for Accelerometer Z (Deg) cont.
7D0-07-03 xx
xxxx xxxx Wheel Ticks to Revolution Front HEX=DECx1+40=Value (unitless)
7D0-07-03 xxxx xx xxxx Wheel Ticks to Revolution Rear HEX=DECx1+40=Value (unitless)
7D0-07-03 xxxx xx
xxxx Tire Circumference (cm) HEX=DECx1+100=Value (cm) x0.393701=Value (in)
7D0-07-03 xxxx xxxx **xx Distance from IP to Rear Axle (cm) HEX=DECx1+100=Value (cm) x0.393701=Value (in)

SYNC Region: NA

Navigation Variant: Nav

Manufacturer Year: Pre MY20

Install Type: Retrofit

Old SYNC Version: 2

New SYNC Version: 3.0.18093

Do you have a error message, if so what is it?

Update Method: Official Ford

If I go into APIM bezel dignostics it shows where tire circumference is 112cm this is not correct does anyone know the correct valve to use ?

All the values from line 7D0-07-03 that I originally used was from the original as built for the wreaking yard apim.

The other thing I noticed is if I scroll through the configuration in bezel diagnostics it says gas type is “diesel” when I have line
DE00/7D0-01-02: xxxx-*xxx-xxxx set to “0”

0=Gas Vehicle, SWAC Not Available

Location information in the apim bezel diagnostics does not show any information either

There are a few things that don’t seam to jive

I found this thread , could this all be related to the fact I’m not on sync 3.4 ?

ive been playing with the as-built and i’m totally lost as to what the issue could be

i went on ebay and got a few different VINS from a lincoln mkx and looked at the corresponding tire sizes . I then went to Fords as-built site and viewed line 7D0-07-03
there were a few with the value of 86 where tire circumferance would be. i tried this value . did a master rest and took the car for a drive. gps was way out

i then found this thread

and tired this Hexadecimal to Decimal converter that was in the above thread Hexadecimal to Decimal Converter

i pulled up the circumference in the BCM as it accounts for “tire squish” with a corrected value . (242cm) if i put 242 into the hex converter i get F2.
i then put F2 in location 7D0-07-03 xxxx xx** xxxx
the GPS is just as inaccurate.

everytime i was making a change and writing the asbuilt i was preforming a master reset right after. i would then go to the test screen

Test settings
clear DR calib
and then go for a 15min drive making at lease 4 right and 4 left turns the longer i drove with all configurations the worse the accuracy would get then it would jump back on the road after making a turn. The red icon GPS marker would turn short and show in the field.

playing with the circumference hex formula would bring me back to the as built data supplied by Fords data base
HEX=DECx1+100=Value (cm) x0.393701=Value (in)
86=134x1+100= 234cm

First things first, IGNORE THE BEZEL DIAGNOSTICS DATA. This is nothing but the base load for all Sync 3 vehicles with some reflected changes in the asbuilt. (This is the base settings as defined in the Sync application JSON files.)

Secondly, make sure the GPS is working. You cannot resolve this issue if it is not.

Now once the GPS is functioning correctly, Fill in the Specific Vehicle Data fields in the asbuilt with a 2016 Edge or MKX APIM asbuilt. It is probably better to load the entire APIM asbuilt and start from there. This should make the GPS and Nav work, and if there is a wandering issue troubleshoot from there. Entering just any values trying to troubleshoot this will not really work as the Nav needs to be able to ‘dead reckon’ based on the last GPS location. If you don’t have a trusted location, it just won’t work.

thanks for responding . I originally did that when I went from the sync 2 to sync 3. I then went through the As-Built data base line by line and made my changes accordingly.

the Nav works its not 100% accurate it will get progressively worse when driving in a straight line and when you come to a stop sign it will be visibly off on the map then it will correct itself. driving in the city using carplay or nav is tough

I would be very greatful if someone with more knowledge then me would be able to look at these few photos as i’m totally at a lose.

Here is the GPS location diagnostics from my unit,

I have spent most of the day reading threads and trying to configure/compare the As-built against My sync 3 install, the only varation i have found with the MKX depending on the vin is tire Circumferance and internal Gyro. (besides the obvious options) i have changed a few values back and forth But cant seem to Fix the inital issue.
I dont know what i’m looking at, but i’m wondering if the antenna i have is in fact a POS!

the 2D and 3D accuracy will progressivly get larger and larger. when you stop for a second at a stop sign or traffic light it will catch up.

The Tire Circumference HEX changes in the as built depending what tire size came on the vehicle from the factory i have tried both factory HEX values for an mkx (84) and (86). All the data was pulled from using Vin numbers from Ebay Motors

i currently have this value set to 8E as corresponds with the current tire size of 265/40-22. For what its worth this is the size that is used in the current BCM settings as well.

No matter what setting i have tried its like the GPS cant keep up with how fast the car is traveling. I wouldnt care other then the fact that this messes up apple car play as well.

i even updated the sync to a newer software version thinking that might solve the issue, it did not!

Here is a side by side comparison.

As mentioned in an earlier post every time i made a change i did a master reset.

Thanks in advance

The nav accuracy is way off, it should be sub 10 meters. The time to first fix is too long. Also the heading is not correct. All of this is independent of the Vehicle Settings, this is an indication that the antenna is weak. The fact that the GPS is wandering and the location fix is not accurate would bear this out. Just because the APIM can see the satellite does not mean the signal is good enough to decode the GPS positional data. Keep in mind the nav and satellite receiver are not controlled by Sync 3 and are independent subsystems of the APIM. These could also have issues by themselves which can cause these issues. However, it comes down to the satellite data is not correct and you can’t fix that through Sync.

The data for 7D0-07-xx from the 2017 MKX should work fine for the 2011 MKX, as there were no significant changes to the vehicle over those years.

you mentioned that the “heading is not correct” when i took this picture the vehicle was just sitting parked. would this make any difference ?

Hi, I am having this exact same issue with Ford Mustang that I have upgraded from Sync2 to Sync 3 with a kit from ebay. Everything works fine expect for this GPS issue exactly as you have described, 2d and 3D accuracy gets worse the faster I go, but all other GPS indicators, no of satellites HDOP signal strength are all good.

Not sure where you mounted the gps antenna.

I had mine attached to the top edge of the screen(magnetic antenna).I moved it onto the dash and it fixed the problem. 2d and 3d accuracy is within 2 meters anytime I pull it up.

Line 7d0 03 01
I changed from roof mount to IP mount antenna that didn’t make any noticeable difference. Not sure what your as build looks like.

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Your asbuilt is likely wrong for the vehicle parameters.

Yes this was the problem exactly. For whatever reason it was sent wrong for the seller even though the had my vin.

I found a car online that came with Sync 3 used that data and it actually got worse!

I then used a forscan asbuilt comparer and it showed that the asbuilt I downloaded was identical to my car. So the one I found for sale must have retrofitted Sync 3 along the line.

I found another car for sale with sync3, got the vin, got the as built compared to mine and saw it was different, used the different settings in my car and problem immediately solved. All is good now.

In the meantime the seller was telling me I needed to attach my GPS to the A Pillar and it was centre speaker causing interference :joy:

Glad you got it sorted. Thanks for the feedback.

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