How to: Recalibrate Speedometer with Forscan for 2021 Bronco

[Perfect-Beast-2]

Tarikh, most 35s aren’t exactly 35.0” in diameter. For example, Sasquatch tires (LT315/70 R17) are 34.4” diameter, so the circumference for that tire would be 2741 mm. Not a big difference between 2741 and 2791, but it’s still smaller. So be sure to use your exact tire diameter, and not the nominal diameter marketed by the tire maker. Might as well be exact, if you can.

Source: 2021 Bronco Factory Tire Size & Wheel Size Comparisons (Circumference, Diameter, Height, Width, Bolt Pattern, Center Bore)

I just used a tape measure and google to convert 34" to mm. Oddly, I get better gas mileage with larger tires after changing in forscan than I did with BD stock tires. I wonder if Ford had the wrong number in there before. Understanding of course that the computer is figuring out the mileage not real world by me.

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[rtaylor]

Bumping this thread, any updates / fixes to PCM 160a error?

Use the PCM service function instead of the PCM relearn. The PCM relearn doesn't work.

UPDATE: on new Forscan versions (2.3.52+), " PCM Module initialization/relearn vehicle data" is reported to work.

Detail:
1- I used FORScanSetup2.3.47.test20220221 (version that supports MY2022 goat modes) with OBDLink EX. You will also need a FORScan demo license.
FORScanSetup2.3.47.test20220221.exe

2- Set front/rear TPMS and tire size in BdyCM. For KM3 37x12.50R17D on sasquatch wheels, use 35psi and 2760mm. For sasquatch stock tires and wheels, use 39psi and 2653mm. Tire circumference cannot exceed 2800mm. DTC's will be set in 2-3 modules that will need to be fixed.

3 - To fix the non-PCM DTC's, run the AWD relearn. Don't run the PCM relearn (it doesn't work).

4 - Clear the DTC's. All should be cleared except PCM.
5 - Run the PCM reset-all-adaptations service function. This will fix the size mismatch and also clear the PCM DTC. It will relearn the engine/trans/fuel adaptations over time while driving. UPDATE: on new Forscan versions (2.3.52+), " PCM Module initialization/relearn vehicle data" is reported to work.

6 - Confirm all DTCs are cleared.

7 - Install a free speedometer app with tenth-mph readout on your phone and testdrive to confirm speed is within 0.5mph at 60mph cruise control. For new tires, the actual speed should be a little higher than speedo. For worn tires the actual speed will be a little less.

 

[redone17]

Thank you @rtaylor.

I was going to leave it - but, my OCD is driving me a little .

 

[Illini_STL]

Use the PCM service function instead of the PCM relearn. The PCM relearn doesn't work.

Detail:
1- I used FORScanSetup2.3.47.test20220221 (version that supports MY2022 goat modes) with OBDLink EX. You will also need a FORScan demo license.
FORScanSetup2.3.47.test20220221.exe

2- Set front/rear TPMS and tire size in BdyCM. For KM3 37x12.50R17D on sasquatch wheels, use 35psi and 2760mm. For sasquatch stock tires and wheels, use 39psi and 2653mm. Tire circumference cannot exceed 2800mm. DTC's will be set in 2-3 modules that will need to be fixed.

3 - To fix the non-PCM DTC's, run the AWD relearn. Don't run the PCM relearn (it doesn't work).

4 - Clear the DTC's. All should be cleared except PCM.
5 - Run the PCM reset-all-adaptations service function. This will fix the size mismatch and also clear the PCM DTC. It will relearn the engine/trans/fuel adaptations over time while driving.

6 - Confirm all DTCs are cleared.

7 - Install a free speedometer app with tenth-mph readout on your phone and testdrive to confirm speed is within 0.5mph at 60mph cruise control. For new tires, the actual speed should be a little higher than speedo. For worn tires the actual speed will be a little less.

thank you so much

 

[redone17]

That seemed to have worked! Going for a test drive now. Thanks!

Edit: I got my speedometer to be within 0.5-1 MPH of Waze and another GPS app on my phone. I ended up adjusting it down to 2620mm for 285/75R17. I need to do a run on the highway on cruise control. But, for now I am happy. It was about 4 MPH under at 30, and 8 MPH under at 60.

 

[balber]

Use the PCM service function instead of the PCM relearn. The PCM relearn doesn't work.

Detail:
1- I used FORScanSetup2.3.47.test20220221 (version that supports MY2022 goat modes) with OBDLink EX. You will also need a FORScan demo license.
FORScanSetup2.3.47.test20220221.exe

2- Set front/rear TPMS and tire size in BdyCM. For KM3 37x12.50R17D on sasquatch wheels, use 35psi and 2760mm. For sasquatch stock tires and wheels, use 39psi and 2653mm. Tire circumference cannot exceed 2800mm. DTC's will be set in 2-3 modules that will need to be fixed.

3 - To fix the non-PCM DTC's, run the AWD relearn. Don't run the PCM relearn (it doesn't work).

4 - Clear the DTC's. All should be cleared except PCM.
5 - Run the PCM reset-all-adaptations service function. This will fix the size mismatch and also clear the PCM DTC. It will relearn the engine/trans/fuel adaptations over time while driving.

6 - Confirm all DTCs are cleared.

7 - Install a free speedometer app with tenth-mph readout on your phone and testdrive to confirm speed is within 0.5mph at 60mph cruise control. For new tires, the actual speed should be a little higher than speedo. For worn tires the actual speed will be a little less.

I would just like to give a shout out! thanks rtaylor! Just did above and this solved all my existing DTC issues with NOT being able to run the PCM Relearn. I ran AWD relearn without issue, then I reset all adaptations on PCM, cleared the DTC log and cycled engine. Looks like all went away but one and that's related to my speaker system. Going to let it run a while and see if it clears, but I"m guessing that has to do with how I wired the amp to the speaker system.

5 minutes into a test drive, shift points are better, RPMS are staying up and it is responding like when I had it when there were 32's. Kuddos man!

 

[redone17]

I would just like to give a shout out! thanks rtaylor! Just did above and this solved all my existing DTC issues with NOT being able to run the PCM Relearn. I ran AWD relearn without issue, then I reset all adaptations on PCM, cleared the DTC log and cycled engine. Looks like all went away but one and that's related to my speaker system. Going to let it run a while and see if it clears, but I"m guessing that has to do with how I wired the amp to the speaker system.

5 minutes into a test drive, shift points are better, RPMS are staying up and it is responding like when I had it when there were 32's. Kuddos man!

Is it the same speaker DTC as this?

ACM: Code: B1A06 - Speaker #6

Additional Fault Symptom:

- Circuit Open

Status:
- DTC Present at Time of Request
- Malfunction Indicator Lamp is Off for this DTC

Module: Audio Control Module

 

[balber]

Is

yep!!! That’s the one

 

[redone17]

yep!!! That’s the one

Mine is doing the same thing. No idea why. All speakers are working fine. I did the ACM change to accommodate for full range in the back…did you?

 

[balber]

Mine is doing the same thing. No idea why. All speakers are working fine. I did the ACM change to accommodate for full range in the back…did you?

that must be what it is, I did the same thing. I also added a sub/amp but I’ve checked all my connections.

 

[redone17]

that must be what it is, I did the same thing. I also added a sub/amp but I’ve checked all my connections.

I’m going to change it back to stock and see…

 

[balber]

I’m going to change it back to stock and see…

Let me know

 

[7amanino]

Use the PCM service function instead of the PCM relearn. The PCM relearn doesn't work.

Detail:
1- I used FORScanSetup2.3.47.test20220221 (version that supports MY2022 goat modes) with OBDLink EX. You will also need a FORScan demo license.
FORScanSetup2.3.47.test20220221.exe

2- Set front/rear TPMS and tire size in BdyCM. For KM3 37x12.50R17D on sasquatch wheels, use 35psi and 2760mm. For sasquatch stock tires and wheels, use 39psi and 2653mm. Tire circumference cannot exceed 2800mm. DTC's will be set in 2-3 modules that will need to be fixed.

3 - To fix the non-PCM DTC's, run the AWD relearn. Don't run the PCM relearn (it doesn't work).

4 - Clear the DTC's. All should be cleared except PCM.
5 - Run the PCM reset-all-adaptations service function. This will fix the size mismatch and also clear the PCM DTC. It will relearn the engine/trans/fuel adaptations over time while driving.

6 - Confirm all DTCs are cleared.

7 - Install a free speedometer app with tenth-mph readout on your phone and testdrive to confirm speed is within 0.5mph at 60mph cruise control. For new tires, the actual speed should be a little higher than speedo. For worn tires the actual speed will be a little less.

Thanks Alot that was helpful Dtc cleared

 

[GRAYFOX-SVT]

Just wanted to give my experience on this for anyone else who runs into an issue. I have an Outer Banks and changed the wheels / tires over and wanted to correct the MPH. I went up to 285/70/17 tires.

I set the MM circumference value and hit write, as soon as I did this I got a CEL for the 4 wheel drive system / service soon. I did the step on page 1 for resetting the AWD module and after doing this I no longer had the CEL notification. I shut the vehicle off and turned it back on and the CEL did not come back. I wont be driving it again until tomorrow but it appears as though everything is all set.

 

[RustysBronco]

Use the PCM service function instead of the PCM relearn. The PCM relearn doesn't work.

Detail:
1- I used FORScanSetup2.3.47.test20220221 (version that supports MY2022 goat modes) with OBDLink EX. You will also need a FORScan demo license.
FORScanSetup2.3.47.test20220221.exe

2- Set front/rear TPMS and tire size in BdyCM. For KM3 37x12.50R17D on sasquatch wheels, use 35psi and 2760mm. For sasquatch stock tires and wheels, use 39psi and 2653mm. Tire circumference cannot exceed 2800mm. DTC's will be set in 2-3 modules that will need to be fixed.

3 - To fix the non-PCM DTC's, run the AWD relearn. Don't run the PCM relearn (it doesn't work).

4 - Clear the DTC's. All should be cleared except PCM.
5 - Run the PCM reset-all-adaptations service function. This will fix the size mismatch and also clear the PCM DTC. It will relearn the engine/trans/fuel adaptations over time while driving.

6 - Confirm all DTCs are cleared.

7 - Install a free speedometer app with tenth-mph readout on your phone and testdrive to confirm speed is within 0.5mph at 60mph cruise control. For new tires, the actual speed should be a little higher than speedo. For worn tires the actual speed will be a little less.

What gearset do you have in yours?

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