Ford Focus ST Deflation Detection System Troubleshooting

I recently swapped my OEM snowflakes to a set of 17″ titanium rims wrapped in some new Blizzaks for my winter setup. I crossed my fingers that the stock TPMS sensors from the titanium would work, but I couldn’t get the “deflate until horn honks” procedure to work. So instead of forking out some cash for new sensors, or disabling TPMS, I decided to take a shot at using Deflation Detection System (DDS) instead. This is the ESC sub-system that uses the wheel speed sensors (I believe) to detect when a wheel has a smaller circumference than expected and trigger the tire pressure light. I was only able to find two accounts of people trying this, one of which reported that it doesn’t work, one reported that it does. So I fired up FoCCCus and changed the appropriate field from TPMS to DDS.

I’m happy to report that it works flawlessly on my 2013 FoST! I followed Ford’s parameters of resetting the system in the IPC under driver assist and gave it at least 13 miles of normal driving to learn the parameters. Then I dropped one tire from 35 psi to 20 psi. Within 3 miles of driving, the IPC reported a low tire pressure and the cluster light illuminated.

This is pretty awesome. No need to fool around with which sensor went bad.

 

Good to know:

In my opinion, TPMS is nice until the sensors fail or the batteries start to become marginal. In my case, I was willing to disable them (for off road use, of course) rather than figure out which one is bad, buy another one, then pay my tire shop to re-mount my blizzak. To do it right, I would do all 4, which would be an added expense. DDS has been a boon for my time and my wallet. I like this system much better, even though it’s less accurate, under the “less is more” philosophy. Less parts to break/replace, and a clever way of executing a government mandate that’s already dubious at best.

 

Update:

Not on the DDS functionality, as it still works flawlessly, but rather about the TPMS sensors from my 17″ Titanium rims. With an Autel MaxiTPMS TS401 reader, I confirmed that the Titanium rims have 315mhz sensors, and my factory snowflakes are 433mhz. This is why I wasn’t able to get the re-learn procedure to work.

Autel MaxiTPMS TS401

This surprised me, as the rims came from a 12-14 Titanium according to the part number and design and my FoST is a 2013. I was under the impression that all pre-facelift (and maybe even 2015-17) Foci used the same TPMS sensors.

Oh well, DDS is perfectly sufficient. I might keep it active even when I return to the snowflakes in the Spring.

 

Question: where buy the focccus software just for this feature.?

Answer: FoCCCus is free. I used an ELM327 cable clone.

elm327-bluetooth-usb-review-1

I should also mention that I restarted the ABS module after enabling DDS in FoCCCus. This is done on the ABS tab, either using the Reset ECU or Initialize ECU (I can’t remember which, but I think it was initialize) button. This cleared the low tire pressure light. I then cleared any DTCs through Forscan.

So in some of the cases I’ve found where people couldn’t get DDS to work, I suspect it’s for one of a few reasons:

1) The “learning” procedure was not executed correctly. Start this under driver assist -> Deflation Detect (hold until it says “Tire pressure stored”), then do at least 13 miles of mixed driving
2) Deflated tire scenario was not tested for long enough. It takes at least 3 miles of continuous driving, and DDS will only detect a loss of psi if it’s at least 25-30% of what it was when the learning procedure was executed.
3) ABS module was not reinitialized as described above.

 

Ford’s General Service Bulletin regarding DDS:

https://mega.nz/file/IVwFRLZA#gsDTPGfOvSMLEMHJBJEr3jgxW13QY1VS9b3K08fDCyE

 

Question: when you correct tire pressure, does it automatically turn off?

Answer: It doesn’t automatically turn off when you correct the tire pressure. The light will remain illuminated until you re-initialize the learning cycle (system information -> driver assist -> deflation detect). When I did that, the light turned off immediately.

 

Big thanks to @ Melchior for his contribution.

 

Thanks to Laurance for editing.

 

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