Correct your speedometer error - no flash or tune required

[Spart]

Process of elimination - maybe we need to be looking at the ABS as-built.

Or maybe we don't.... uggh.

So I compared four different cars. ABS is module 760.

Blue is GT Manual with 3.55's.
Green is GT Manual with 3.31's.
Purple is GT PP Manual with 3.73's.
Brown is GT Auto with 3.15's.

At first you might think, hey! Lots of differences! But not really. 760-01-01 through 760-01-04 are merely the VIN.

That leaves us 760-02-01 and 760-02-02 as the only lines that have meaningful differences.

The first digit of 760-02-01 would seem to correlate to whether the car is an auto or manual. Not helpful.

The fifth digit of 760-02-02 does change, but for some reason is the same for the GTPP with 3.73's and the Auto GT with 3.15's.

The fifth and sixth digits of 760-02-02 seem to correlate to whether the car is a PP or not. I do know that the fifth digit seems to control whether you're able to use the drive mode toggle when you do a swap from base to Sync 3.

Maybe the ABS needs a relearn procedure just like the PCM does? :frusty:

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[Spart]

I'd go back and make sure nothing was damaged with the ABS sensors when you did the axle / rear swap. Sounds like it's in limp mode. Try pulling the fuse or disconnecting an ABS sensor and see what happens - since apparently it does it regardless of what value is in the BCM - if I'm reading your posts correctly.

I really doubt it. I've talked to three people now that have this same sort of issue with a diff swap.

 

[Elit3Sally]

I really doubt it. I've talked to three people now that have this same sort of issue with a diff swap.

But out of these 3 issues, are we all showing the same? I asked my ford service friend as well as my tuner it seems my hub bearing is faulty ( hence the code )

 

[Spart]

But out of these 3 issues, are we all showing the same? I asked my ford service friend as well as my tuner it seems my hub bearing is faulty ( hence the code )

These guys haven't resolved the issue, but I talked to another guy on FB a while back that fixed it by going back to the stock rear end. I asked him to visit this thread and post his experience so we have some more data to work with.

 

[Brazenbuck]

OK, I just put another 20 miles on my car and it's acting the same way. I'm ready to conclude I didn't catch a tank of bad gas and it's a all about the diff swap. Going back to 3.73. 3:31's aren't worth this headache.

 

[Spart]

OK, I just put another 20 miles on my car and it's acting the same way. I'm ready to conclude I didn't catch a tank of bad gas and it's a all about the diff swap. Going back to 3.73. 3:31's aren't worth this headache.

I'm sure there are some tuners out there who have made these issues go away. I doubt they're willing to give away the secret sauce though, if it turns out this can be remedied through FORScan.

 

[Brazenbuck]

I'm sure there are some tuners out there who have made these issues go away. I doubt they're willing to give away the secret sauce though, if it turns out this can be remedied through FORScan.

You're probably right, but my tuner started this journey by saying there were no PCM/BCM changes required for a gear swap. It's not worth it to me to get another tuner and keep chasing after this.

 

[Elit3Sally]

These guys haven't resolved the issue, but I talked to another guy on FB a while back that fixed it by going back to the stock rear end. I asked him to visit this thread and post his experience so we have some more data to work with.

These guys haven't resolved the issue, but I talked to another guy on FB a while back that fixed it by going back to the stock rear end. I asked him to visit this thread and post his experience so we have some more data to work with.

That's not really an option for me. I'm not gonna rebuild the old diff, the clutch backs are PASTE lol I blown a seal and never noticed so was racing my 3.15 diff with 0.8 QT of fluid vs the recommended 1.8GT. My friend at Ford and my tuner say the error i am getting is a mechanical fault

===ABS DTC C0036:07-AB===
Code: C0036 - Left Rear Tone Wheel

Additional Fault Symptom:
- Mechanical Failures

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

the Speed Sensor in the rear cannot read the Hub so it is throwing off the speed sensor which is jacking up the speedometer and the ABS see's one wheel spinning out of in a different way and thinks the car is sliding .. so im gonna do the replacement and see where we end up

 

[LFCRulesOK]

Does anyone know where the ODB port is on a RHD Mustang? I checked this video out and it said to just look at the opposite (driver's) side, but I couldn't see the port.

[ame="[MEDIA=youtube]4a98GoHbinE[/MEDIA]"]

I swapped out the factory fronts 255 for 285 and 275 rears for 295. Same wheel diameter but an aspect ratio of 35 instead of the factory 40. I also had the Ford Performance Sports Suspension pack and lowering springs installed. Does that affect the speedo as well?

 

[msweet]

Does anyone know where the ODB port is on a RHD Mustang?

Are you being serious? Sit in the drivers seat and look next to your right knee

I did this on my car and it seemed to enable some other setting, felt like a soft limiter kicking in at a specific rev point (different point in different gears). Had to load it back to stock. I've not heard of anyone else having this issue, so not sure if it's an export specific thing or what.

All I did was change that one field and write, did it 5-10 times all with the same result :shrug:

 

[Spart]

I did this on my car and it seemed to enable some other setting, felt like a soft limiter kicking in at a specific rev point (different point in different gears). Had to load it back to stock. I've not heard of anyone else having this issue, so not sure if it's an export specific thing or what.

All I did was change that one field and write, did it 5-10 times all with the same result :shrug:

You need to also do the PCM relearn, which is detailed in the OP.

 

[msweet]

You need to also do the PCM relearn, which is detailed in the OP.

Ah ok, I don't think that was there when I did it almost a year ago. My OBD reader broke, if I buy another one I'll try that

 

[SiMuL]

Ah ok, I don't think that was there when I did it almost a year ago. My OBD reader broke, if I buy another one I'll try that

I had the same issue you did. I thought my throttle body was having an issue. I don't recall a PCM relearn procedure back then either. I'm glad to know there is a fix for the issue I was having, though!!

 

[Spart]

I had the same issue you did. I thought my throttle body was having an issue. I don't recall a PCM relearn procedure back then either. I'm glad to know there is a fix for the issue I was having, though!!

Nope, sometimes it happens with tire size changes and sometimes it doesn't.

Regardless of whether you have it or not, doing the PCM relearn is a good idea. Gets rid of the DTC and your PCM thinks your car came with that tire size from the factory. What it does with that info I can't tell you, but it can't be a bad thing.

 

[stingerbtry]

You're probably right, but my tuner started this journey by saying there were no PCM/BCM changes required for a gear swap. It's not worth it to me to get another tuner and keep chasing after this.

I'm having the exact same issues that you are. I also swapped out the 3.73s for 3.31s and the car goes into limp mode under load. It stays like that for ~10 seconds and then returns to normal. The worst part is that in limp mode the afr goes so lean that I'm getting misfires. It actually broke the electrode inside of one of my plugs and based on the resistance I'm seeing there is another that's almost broken. So you changed the BCM line 0726-12-01 to 014B-XXXX-XXXX and it didn't fix anything? I thought the plugs were my issue and didn't realize that the gear swap was causing this. My tuner, like yours, also said that there were no changes needed with the swap since the speed sensors handled the speedometer. Did you ever figure it out? I ordered new plugs and was just about to put them in and change the BCM to account for the gears and tire size but if that doesn't help anything then I'm not sure what I'm going to do. I really don't want to go back to the 3.73s or drop the rear end again for any reason actually. My brother's a master mechanic and also didn't believe there were no changes to be made after a gear swap. He said at the very least the new pinion ratio would need to be changed in the ABS module or settings (not sure where it's located without opening forscan). I guess that's where I'm going to start looking. Here's a pic of a nearly new plug that's been destroyed as a result:

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