Is there TPMS "Memory" in the GEM/SJB?

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buckyswider
Posts: 18
Joined: Mon Mar 27, 2017 4:58 pm
Vehicle: 2011 Mercury Mariner Hybrid

Is there TPMS "Memory" in the GEM/SJB?

Post by buckyswider »

Hi all, 2010 Escape Hybrid. I've been fighting a TPMS error light for a few years now. the 'ol B2872- Tire Pressure Sensor Fault.

In my early investigations, I discounted that it could be a bad sensor because all 4 show up in FORSCAN with Pressure, ID, Temperature. Thought it had to do with phone chargers and RF interference. Finally went back in today to try to fix it once and for all. Installed new USB ports and put them on a switch to help with troubleshooting.

After that I went back in to FORSCAN and found all the data again. Did the re-learn procedure with the Ford TPMS19 transmitter. Well, I couldn't get one of the wheels to register. But I'm still thinking, well, it has to be good, because Forscan sees it!!!

Figure with nothing else to lose I'd had that TPMS sensor swapped (I had already bought 4 new ones in advance of my new tires, which I forgot to bring with me when I got said new tires :( ). The tire shop swapped out the one that wasn't responding, and everything programmed up easily. Light, message, and code all gone!

So my question is: Does the GEM/SJB keep that last known readings of the 4 programmed sensors in memory? So I could be looking at data from 2 years ago, or whenever it was that the sensor went bad? You'd think there'd be some sort of time-to-live for data- say, if I haven't gotten data from that sensor in x days or whatever, discard what's in memory. This one sure lulled me into a false sense of security!!!
Ecmbuster
Posts: 937
Joined: Sun Mar 15, 2015 4:08 am
Vehicle: Volvo Bertone and two Motorcyles
Location: On a spinning rock

Re: Is there TPMS "Memory" in the GEM/SJB?

Post by Ecmbuster »

Interesting question and never encountered that in any vehicle.
Here's a bit of proof and you can try this simple test with FORScan.

Test it and the theory with TPMS. With FORScan, make sure there no changes and all tires set correctly, take a screen image with KOEO.
Exit and disconnect the OBD device. Remove the key and close the door.

Have your compressor or air supply ready.

Do nothing to this model except make sure all tires are set to factory specifications but drop one tire to 50% less air pressure capacity.
Now test with FORScan KOEO and see if the pressures are read. Take a screen image.
Another piece of information to add and happens with Euro models. They need to be driven, the sensor has to spin under the antenna.
NEVER drive a vehicle with FORscan operating and viewing it at the same time! Use screen recording software and save that movie.
Get a coffee and drive the car around the block a few times with the low tire carefully. With FORScan still connected, stop and then take a screen capture.
Name all your captures and post the experiment.

KOEO = Key On Engine Off
Do not ask for help in PM. Use the forum to ask and answer questions!
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