TPM Hack? - K-Bikes.com - Excellence in Motion
 
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post #1 of 7 (permalink) Old Jun 8th, 2013, 11:54 pm Thread Starter
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TPM Hack?

Some time ago there was a ref to a thread about hacking the tire pressure sensor to
replace the battery, anyone know where that thread is?
I've searched for a while unsuccessfully.

I'm going to try it. I was able to carve out the battery, CR2032, tonight out of a sensor that
was replaced in my front wheel a year ago. Now the back wheel is giving the error. Its also
tire change time so its an opportune time to try replacing the rear sensor's battery.

Do I simply replace the battery and put it back in?

Am wondering what to use to reseal the sensor. Its kind of a rubbery material.

2016 R1200 GSA, 2007 K1200 GT, 1981 CBX, 1975 Norton, 1968 Moto Guzzi
The Banks Tour - Fair to Outer
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post #2 of 7 (permalink) Old Jun 9th, 2013, 12:37 am Thread Starter
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Found it, FYI:
http://www.advrider.com/forums/showthread.php?t=746068
and
http://www.youtube.com/watch?v=Mpjz0cDjnK4

2016 R1200 GSA, 2007 K1200 GT, 1981 CBX, 1975 Norton, 1968 Moto Guzzi
The Banks Tour - Fair to Outer
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post #3 of 7 (permalink) Old Jun 17th, 2013, 1:35 am Thread Starter
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Replaced TPM battery

After seeing the above links I tried it myself, first on a used front sensor as practice that was
replaced in Denver in Sep 2011 when the bike had 16,700 miles on it. Then on the rear
sensor that was becoming bad now with 34,000 miles. I needed to change the rear tire so it
was a good time to try this out.

Getting the battery out isn't difficult as shown in the youtube, just be careful while you are
prying away the rubber like coating. The battery is roughly in the center of the area about
1/16" of inch down. I carefully lifted the old battery out and pried away the tabs that are
spot welded to the old battery. The bottom tab will get bent upward a bit but that is ok since
it will assist with making a good contact to the new battery. I used these batteries with
tabs already spot welded on:

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

I bent the bottom battery tab down a little and put in so the existing tab from the sensor
would push against the tab from the bottom of the new battery. Next I quick soldered the
two top tabs together.

I found that the bottom tabs were pushing the battery up from it intended location so I
dabbed a bit of JB Quik Weld to the high side of the battery and to the case and held it in
place until the glue setup.

Next I layered the area with a hot glue gun to seal it up and let it set up for a couple hours
before putting the sensor back on the rear wheel. So mounted up the new tire and took it
for a spin. It works! So far I only have about twenty miles on it but am heading out to
Dawson City soon and will have 1500 miles on it by the time get home. I'll post again if it
fails.

Hopefully I've managed to attach two pics showing the finished project.
This is definitely do-able and worth trying to avoid $100+ for a new sensor and dealer labor.
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post #4 of 7 (permalink) Old Jun 21st, 2013, 8:06 am
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Great write-up! Many thanks for this information.

So..........do your sensors still work?

This is just the type of do-it-yourself write up that I need, as I just purchased a 2007 K12 and both the sensors are acting up.

Why can't these sensors work as good as the ones you find on basically EVERY automobile?

Originally, I was going to try to just unhook the system altogether, but if they can be fixed this easily, I'll take a stab at that for sure! Thanks again!!!

2007 K1200GT
Dark Graphite Metallic
Bought it with 2,055 miles on the clock - June 2013
Rode 1,100+ miles to get it home
Current miles: 10,350+
Xenon, Remus Hexacone slip-on
BMW small top box (that now likes to fly away on it's own) with pad for the lady

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Last edited by Tom07K1200GT; Jun 21st, 2013 at 8:40 am.
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post #5 of 7 (permalink) Old Jun 21st, 2013, 7:07 pm
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Quote:
Originally Posted by Tom07K1200GT
Originally, I was going to try to just unhook the system altogether,!!!
I don't know how you could "unhook the system"... I have had both of mine go bad at different times, and I would have just left it alone until the next time I needed tires, but what happens is that you get a warning on the OC which won't go away.

Speaking of the TPM, and not intending to hijack the thread here, my TPM indication is always two pounds less than my reading with a manual tire pressure gauge. Does anyone have TPM that reads the same as their gauge?
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post #6 of 7 (permalink) Old Jun 21st, 2013, 10:58 pm
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Quote:
Originally Posted by chuckwilmot
Speaking of the TPM, and not intending to hijack the thread here, my TPM indication is always two pounds less than my reading with a manual tire pressure gauge. Does anyone have TPM that reads the same as their gauge?
This comes up frequently. TPM systems usually correct the actual pressure reading to standard temperature (which I believe is 20C/68F) for internal calculations, but for some strange 'we do it this way at BMW' reason BMW also displays the corrected (vs. actual) pressure on the rider display, resulting in variances from the reading given by a handheld pressure gauge. To make things even more confusing the variation of TPM display reading from that displayed on a manual gauge will be more or less depending on tire temperature at the time so the amount of variation will not be constant. As a result you can't always count on the TPM display matching a pressure gauge, although sometimes it might. All you can really do is set the pressure where it should be with a good tire gauge and let the TPMS do its thing... it will still accurately warn you if the pressure deviates too much, which is its primary function.
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post #7 of 7 (permalink) Old Jun 27th, 2013, 12:54 pm Thread Starter
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partial success

I'm back from a 1500 mile run from Fairbanks to Dawson City (on the Yukon River) that
included several rough construction zones, 110 miles of gravel/hard dirt surface on the Top
of the World Hwy but mostly a mix of pavement and chip seal. Plenty of vibration causing
road surface.

The sensor became intermittent after the first set of rough road on the first day and that
was the pattern for each succeeding 4 days of travel. Now at home on nicer roads it is
doing the same thing but with less time working on each ride.

It will be a while before I have time to pull the rear tire, at least one bead, and remove
the sensor to inspect it.

Assuming the solder connection on the top or positive side has not broken, I may solder
the bottom tab this time. I didn't do that last time since it was held in place with the JB
weld "tab" on top. Another possibility is that I broke something internally in the sensor
when prying the tabs off the old battery. Maybe cutting them off would have been less
stress, if that would leave enough contact length to reach the tab that comes on the new
battery.

I'll report back after the next fix and ride time. I'm not to the point of taking it to the
local BMW dealer yet. Fortunately I have a great dealer in Fairbanks (decent one in
Anchorage too) that has so far been reasonable for maintenance costs for stuff I didn't
want to do and they keep it up to date on recalls and advisorys.

I've learned loads from the rest of you guys so hope this is a way of paying it back.
David

2016 R1200 GSA, 2007 K1200 GT, 1981 CBX, 1975 Norton, 1968 Moto Guzzi
The Banks Tour - Fair to Outer
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