Ranger Mods

OK this is a Stewart question, but someone else may know?

After my recent PCM update I noticed I had the following DTC in the PCM Module
PCM P1635:00-2F
Code: P1635 - Tyre/Axle out of acceptable range.

P1635 - Ford
Type Powertrain - Manufacturer Controlled DTC - Manufacturer Controlled
Description
Tyre Axle/Ratio Out of Acceptable Range Conditions

Cause
Engine running and the PCM detected that the Tyre and axle information in the VID Block does not match the vehicle hardware

I have 285/70/17's fitted and have changed the following in BCM
BCM 726-12-01 xxxx 0977 xxx as per tyre size change

Is the above mentioned VID block something we can access or do I need to go back to the dealer and ask the to fix?

Cheers

Jason

https://forscan.org/forum/viewtopic.php?t=6222#p21543

We receive many complaints that on new cars (usually after 2011-2013 model years) changing Tyre size in BdyCM causes P1635 in PCM and/or TCM.

Models app. after 2011-2013 model years keep Tyre size and axle ratio in BdyCM and other modules (first of all, PCM and TCM) load it from there. Some models have no dedicated TCM module. In these models PCM manages both engine and transmission.

PCM usually requires special function to learn related changes in BdyCM module. This function in FORScan is called "Configuration and Programming->PCM module initialization/relearn vehicle data". As for TCM, only some of them have this function actually implemented. FORScan has no ablity to determine if the TCM has the learning function supported or not. So it shows this function in the list for all TCMs. If you get error in this function, it most likely means that this function is not really suported AND is not necessary because TCM learns new Tyre size in an automated mode.

So far our investigations and investigations of our users show the following:

1. if Tyre size is changed AND PCM and/or TCM have not learnt the new Tyre size, the P160A code will most likely appear. In this case owner needs to run PCM and/or TCM module initialization/relearn vehicle data function.

2. If P1635 appears in PCM or TCM after Tyre size change, it means that the module has learnt the new Tyre size, but this Tyre size is out of allowed range . Actually, this is exactly what P1635 DTC description tells us about:

P1635 - Tyre/Axle Out of Acceptable Range

We suggest a simple test to check this. PCM and TCM modules usually have a TIRESIZE (or similar) PID that shows Tyre size in revs/mile or revs/km (depends on FORScan settings). Owner can add this PID to the Dashboard and check after the Tyre size change in BdyCM configuration (learn function may be necessary). The BdyCM parameter is the Tyre length (2 * Pi * R * 0.967) and TIRESIZE parameter is in revs/mile, but these parameters can be easily converted from length to revs/mile or vice versa.

At this moment the tests show the following behaviour:

i. If the new Tyre size is in acceptable range, the TIRESIZE is changed and matches (learn function may be neccessary)
ii. if the new Tyre size is out of acceptable range, the TIRESIZE becomes the lowest (or highest) possible value.

We suspect the tiresize limits are hardcoded in TCM firmware. The transmission as built data (TRID block) usually contain transmission strategy and solenoid ID numbers and doesn't seem to have the limits (but we cannot guarantee it). Also we do not recommend to play with TRID block as transmission strategy and solenoid ID are critically important for normal transmission work and if these values are incorrectly changed, it will be not good for the transmission health at all.

Hey Ross,

Yeah I did read that in the Forscan forum, I'd like to know if it is fixable?
Again this is after the PCM update.

Cheers

Jason

You can change VID block but it won't help you. As per the above post I went through all this long ago to try and fully resolve the issue.

PX3 I can do any tyre size you want, PX2 no.

Put 0977 back to 0934 and clear DTC and tell me the out come.

Also is this a manual or automatic?

Hi Stewart,

So put 0977 back to 0934 and cleared DTC's all good the code disappears, when I put back to 0977 the DTC reappears. I guess it's not causing any issues but I don't recall seeing prior to the PCM update, but that doesn't mean it wasn't there.

I did bring up the dashboard and had a look for Tyre size, found no reference in PCM but I did in TCM, the problem with that one is that when you select and then enable on the dashboard it's actually revs/min and not revs/mile as the description states and when I went for a drive it stayed fixed at 683 and not changing in real time. The seconds were increasing on the dashboard so I assumed it was running?
First time I've used that function to analyse.

Ute is an Auto mate

Cheers

Go through a range, so try.

0976
0968
0966
0958
0946

See how low you need to go to keep it clear then start coming up again.

Eg. If you find 0970 is ok then start coming up until you find the point where DTC start.

Last character will rotate 1234567890ABCDEF.

Thanks Stewart,
I'll give that a go when I get back from work in a couple of weeks

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