Help! TPMS for Dummies...

[BusaMan]

OK, y'all, I've gone thru every post on this site w/ "TPMS" in it, and I still don't find what I need to do to deal w/ the TPMS values. Specifically, I'd appreciate a detailed description of what I have to do to accomplish the following:
1) Make sure that the wheels are on the "corner" that the TPMS thinks they are. I bought the vehicle w/ Pirelli's installed, and I'm not at all confident that the replacement process put the same rim back on the same "corner"; e.g., is the wheel installed on the Left Front the one the TPMS thinks is on the Left Front.

2) Retrain the TPMS to accept the wheels where they are. I do want to rotate the tires, and not have to take it into the dealer just to get this done.

3) Calibrate the TPMS for each rim. All of my tires have 32 psi at this time (I may well reduce that to 30...), but my LF indicates 28, and the other 3 show 30 psi.

It was interesting to learn that the system only updates periodically, and doesn't show an instantaneous change in pressure. Wish there were a way to force an update, tho...

TIA

Tim

 

[mtrocket]

I think that changes to psi, corners, etc. have to be reprogrammed using a TPMS unit, which most tire shops (or dealers) have now. One of the downsides to having TPMS... or one of the upsides, if you happen to be a tire shop or dealer (ka-ching, ka-ching...).

 

[GizmoQ]

OK, y'all, I've gone thru every post on this site w/ "TPMS" in it, and I still don't find what I need to do to deal w/ the TPMS values. Specifically, I'd appreciate a detailed description of what I have to do to accomplish the following:
1) Make sure that the wheels are on the "corner" that the TPMS thinks they are. I bought the vehicle w/ Pirelli's installed, and I'm not at all confident that the replacement process put the same rim back on the same "corner"; e.g., is the wheel installed on the Left Front the one the TPMS thinks is on the Left Front.

2) Retrain the TPMS to accept the wheels where they are. I do want to rotate the tires, and not have to take it into the dealer just to get this done.

3) Calibrate the TPMS for each rim. All of my tires have 32 psi at this time (I may well reduce that to 30...), but my LF indicates 28, and the other 3 show 30 psi.

It was interesting to learn that the system only updates periodically, and doesn't show an instantaneous change in pressure. Wish there were a way to force an update, tho...

TIA

Tim

Having built and installed aftermarket TPMS systems, your questions seem naive to me, but let me try to alleviate some of your concerns. The answer to number one is to take your car somewhere you can air up the tires and with the key on, let all the air out of one tire at a time till the DIC shows a warning - it will tell you which tire it thinks is the problem. Then put air back in that tire and repeat for the remaining three. (Actually if you set the DIC to front or rear tire pressure, it will display current value updated every minute).

If the TPMS are not where the car thinks they are, I recommend visiting your local Cadillac dealer any day but Monday sometime after 3PM. I have had two dealerships reset my TPMS at that time and it took less than 10 minutes and neither charged me for the service (one was around the corner from our hotel in Charleston during last years XLR group trip).

Calibration of the TPMS is not possible, neither is changing the batteries. If its off by more than you can stand, you can first try a moderate road trip (30-100 miles) the TPM system is supposed to be self calibrating and this is done over an (unknown, to me) interval when the wheels are in motion. I have experience several instances when new TPMS sensors loose contact with the car and a quick roadtrip fixed the problem. If that doesn't work, your only other alternative is to replace the sensor - I think they go for ~$68 each.

The TPMS system on our cars is much like the ones I setup for CarPCs. They update routinely every minute or so as long as specific thresholds are met. As soon as the system sees a sensor outside the designated thresholds, it updates every 10-15 seconds until returned to within normal thresholds. I believe the standard thresholds for our cars are 25psi - 42psi. Anything outside that range will trigger a message on the DIC and initiate faster updates.

Hope that helps.

 

[ChicagoDave]

OK, y'all, I've gone thru every post on this site w/ "TPMS" in it, and I still don't find what I need to do to deal w/ the TPMS values. Specifically, I'd appreciate a detailed description of what I have to do to accomplish the following:
1) Make sure that the wheels are on the "corner" that the TPMS thinks they are. I bought the vehicle w/ Pirelli's installed, and I'm not at all confident that the replacement process put the same rim back on the same "corner"; e.g., is the wheel installed on the Left Front the one the TPMS thinks is on the Left Front.

2) Retrain the TPMS to accept the wheels where they are. I do want to rotate the tires, and not have to take it into the dealer just to get this done.

3) Calibrate the TPMS for each rim. All of my tires have 32 psi at this time (I may well reduce that to 30...), but my LF indicates 28, and the other 3 show 30 psi.

It was interesting to learn that the system only updates periodically, and doesn't show an instantaneous change in pressure. Wish there were a way to force an update, tho...

TIA

Tim

I had Sears redo my TPMS' for $20 - took about 15 mintues. One thing to keep in mind is that they "go to sleep" if not moved for like, 10 minutes or so (to save battery life) ... the guy just banged on the sidewall to "wake up" the sensor.

I found a "tool" for resetting the TPMS' from TireRack - it was pretty inexpensive. Haven't seen how well it works yet, though, my tires have been fine ever since.

Good luck!

 

[BoughtTheXLR]

To set the tire pressure sensor locations all you need is a decent size magnet.

turn on accessory power

Press and hold both lock and unlock on the fob until the horn chirps.

Place the magnet very close to the LF tire stem. The horn will chirp when it is recognized. No chirp? get a stronger magnet.

Repeat for RF, RR, LR in order

turn the car off

By the way, I've read that the learn procedure has 1-minute timeouts between the required actions.

 

[BusaMan]

Thanks for the responses. The Tire Rack lead to that trigger tool (the CUB model?) will probably get me what I need. Thanks, Chicago Dave!

I acknowledge the "naiveté" observation, as this is my first vehicle w/ TPMS. We usually buy vehicles and keep them for a long time, so I'm not as "worldly" as those who routinely keep up to date w/ the newest offerings. As it turns out, our 2011 SRX seems also to have the same system, so the trigger tool would appear to fit the bill for both cars.

Sure wish there were a way to calibrate those sensors. Seems to me to be a fairly trivial software element to add. Oh well...

Thanks again.

Tim

 

[XFireXLR]

After you get your TPMS issues taken care of, have your tires filled with nitrogen. Nitrogen is a bit more stable than air and will not fluctuate with temperature changes.

 

[Lola's Mom]

...
I acknowledge the "naiveté" observation, as this is my first vehicle w/ TPMS. We usually buy vehicles and keep them for a long time, so I'm not as "worldly" as those who routinely keep up to date w/ the newest offerings. ...Tim

Same here, Tim .... We're so backward we don't even get the whole BlueTooth, Ipod, etc. thing. It doesn't matter ..... you will enjoy your car just as much Maybe more since you're not going to spend your time worrying about it .... Just have fun with it and make good friends with your local Cadillac tech - they can be your best friend and teacher .... BTW, we had all of tires replaced at Discount Tire and they did a perfect job with the TPMs .... come to find out, the local Cadillac dealer doesn't have the equipent there to install tires and was going to send the car to the same place to have it done. Saved ourselves about 25%.

 

[ChicagoDave]

After you get your TPMS issues taken care of, have your tires filled with nitrogen. Nitrogen is a bit more stable than air and will not fluctuate with temperature changes.

I've done the same - my psi's do not fluctuate nearly as much now, as they did with regular AIR.

 

[BusaMan]

After you get your TPMS issues taken care of, have your tires filled with nitrogen. Nitrogen is a bit more stable than air and will not fluctuate with temperature changes.

My '64 'Vette, that I bought a coupla years ago, came w/ nitrogen-filled tires. They DO seem to stay real stable, but my issue is that I have to drive about 55 miles to get to the nearest (that I know of) place w/ nitrogen. I have a compressor in my garage.

When I was a (motorsports) dealer, I had a nitrogen tank, just for tires. One of my new tech's left the valve slightly open, and it all leaked out overnight. Cost me over $200 to refill the tank.

I tried the "magnet by the valve stem trick", but no joy. It's a pretty stout magnet, but it didn't haul the freight on this one. I think I might spring for that CUB TPMS Trigger Tool from Tire Rack. Looks promising.

Thanks, all.

Tim

 

[Crimson Pearl]

I run nitrogen in the tires on my XLR as well.

Also in my Tahoe, the nitrogen is much more stable.

Both have TPMS, which makes it easy to keep an eye on the pressures. Interesting comparison between the two vehicles, as one is driven a lot and one is not!