TPMS woes

[Pursuit]

Bill,
I am still running the RSA's. A little more road texture transferred into the body. And that annoying "pinging" when each tire hits a crack in the road. Reminds me of the 2004 Z06 rims with the Goodyear F1's Supercar tires.

Maurice

[elc32955]

Just getting ready to hit 30K miles and my RSA's are getting close. I'll make the road trip later this month with them, but after that it's probably tire change time. Haven't figured out what I want to go with yet... Police price on the RSA's is cheap but don't think I can get that discount anymore...lol

[Navy Lifer]

I've got a set of "brand new" RS-A's if you're interested....

[elc32955]

Hmmmmm....sounds interesting. I'll get with you on those probably as soon as we get done with the meet and I get back. Who knows, after next Friday night the rears could be slicks... (GRIN)

Also my TPMS has been giving me fits again with the reduced temperature. It loves to alarm on the LR tire. I'll have to give my tires a little shot soon. Manual callout is 36 PSI all the way around for non-pursuit work, but get down to 34 PSI and it's alarm time. It's probably attuned to the 39/44 PSI callout for patrol work.

[Navy Lifer]

Eric, that's what I find a little confusing for me, as I mentioned in my Tuesday post. With the lower temps and tire pressures here, as fall has progressed and lower AM temps are becoming "normal", the alarm system is remaining "quiet".....yours is acting like mine was earlier this year. I was, admittedly, running lower than prescribed pressures (34-35 PSI), but I'm wondering if there's a temperature offset that comes into play with the system--ie. in colder weather, the TPMS factors in an allowance for pressure being lower from cold start, knowing that as the car is run for a period of time that temp, thus pressure, will normally rise (at least until really cold winter temps arrive), so that an alarm is suppressed for a long enough period to prevent "nuisance" indications when everything is actually OK.

In Florida, your car would probably still be above that temp where any alarm suppression would come into play--if that is, in fact, part of the system's M.O.

[Navy Lifer]

Well, I think part of my question in the above post has been answered.

Scenario:

Car sits overnight in garage, in low 50's - outside temp is right at freezing.

Back car out, check cold pressures - 34 PSI on all 4 tires by gauge.

TPMS shows pressures as (compared to gauge checks):
LF 31
LR 32
RF 32
RR 31 *with low pressure alarm

Drive car about 30-35 miles, with exterior temps indicated at 27F - 28F, start to finish.

At end of trip, TPMS shows pressures as:
LF 33
LR 35
RF 34
RR 34 *with low pressure alarm STILL indicated

Interesting that one tire (LF) remains "normal" at lower indicated pressure than the one in alarm

Question 1. Does an low pressure alarm clear "real time" as pressure reaches level above sensor alarm setting, or does it require going through a start cycle?

Question 2. Will multiple low tires display on DIC, or just the first that indicated low?

I'm sure some of the answers to my questions are in the owner's manual.....just wanted to put this out for any comments.

[Navy Lifer]

Learned more today from dealer tech. Also rotated tires, reset sensor positions, inflated to 36 PSI, cleared warning. There is a question of whether the spare may have been the source of the low alarm, since it was well below normal, but tech says not likely. TPMS apparently only looks at the 4 on-ground positions, but we're going to determine if the DIC/RCDLR (remote control door lock receiver) are capable of monitoring and setting alarm on the spare.

RCDLR is what controls settings/limits in TPMS, per the tech. He says we will be able to re-set the "normal" to whatever pressure is desired. The default settings for PPV create nuisance alarms for pressures that are entirely reasonable and would not normally turn on the alert on the IP. This means the system could be set to turn on the alarm by a pressure as low as desired, and that would end nuisance alarms--but it would still be possible to read pressure in each tire in real time.

I'll be getting the car to the tech in the next couple of weeks--much other "stuff" going on for now.

[Navy Lifer]

OK, as posted in my last report (above), the TPMS alarm threshold setting CAN be adjusted via the RCDLR. Went to the local dealer and got with their tech, and re-set the system (with Tech2 tool) to not alarm until 30 PSI. With 35-36 PSI "cold" settings I'm using, this should keep the system out of alarm territory unless tire(s) really ARE low. It also doesn't mean I won't monitor pressures and just wait for an alarm, as no one should. No more nuisance alarms!!!

TPMS is a fallable system--sensors do not always (or even usually) read the same pressure as a manual gauge will. It's not a matter (to me) of which is correct, but I'll generally go with the manual gauge reading before I'll trust the sensors, since, as mentioned previously, a gauge check validated same pressure on all 4 wheel positions, but TPMS indicated pressures were not consistent with the gauge check.

Where trouble starts is when the end-user (owner or family member) does a check via TPMS and finds that the tires are:

a) not displayed as being inflated to the same or "correct" pressure in all 4 positions

or

b) tires are not actually at pressures displayed on TPMS (a normal condition, in reality).

For example, someone--maybe tire shop personnel, or even an owner--makes pressure adjustments to individual wheel positions so the pressure displayed matches. Not saying anyone here would do that, but some owners of vehicles with TPMS are just that un-informed to think that all is "good" if the pressures all check the same. It actually happened on my last visit to a Discount Tire store (the free rotation & inflation service)--guy said he was going to adjust pressure on one position, and I said....no, you are not!

Deterioration of the sensor performance over time (battery life issue) would be something to think about, too. Local tech says the lifespan is in the 5 year range (did not look at Owner's Manual to see if anything is mentioned about this)--just something to be aware of.

[The Tech]

I have found on my car that the readings for the TPMS are real time but the alarm for low pressure does not go off until the pressure has increased by 6 psi. My sensors go to alarm at 31 or 32 psi but remain on until the pressure in the tire reads 37 or 38 psi. I have seen the same thing in different rental cars over the past couple of years. But at least my low fuel alarm comes on when I still have three gallons of gas.

[phastlt1]

Ok, I've been reading this thread (due to the fact I now have an issue) and have not read anything near what I'm experienceing. My car has just over 18k on it. I was driving down the road this morning, and got a TPMS failure warning. I am getting no pressure readings on any tire. I did have to put my spare on yesterday, as I destroyed the LF wheel by hitting something in the road while trying to avoid flooding on the roadway. Anyone else experiece an issue like this?