Oh well

 

I have read reports of "seat computers" failing on mercedes before. Seat computers, that's actually a thing.

 

 

I will just stick with my old, tired miata, maybe I can make it to 250k. Sounds like the guys need to make MS4, direct injection, seat, body, tire, with extra future computer disabling features for some of us.

 

Anyway, my original point was, I like Ian's pressure monitoring system. It seems far more reliable than the modern OEM equivalent, currently available (mandatory?)

 

I don't think its mandatory, its just added on as a "keeping up with the Joneses" feature. The new Ford comes with a backup camera tied into the infotanment system? Well, we better add this to all new GMs, can't let Ford get a leg up on us. As a result, the prices keep going up and quality keeps going down.

And I'm not talking about $60k luxosports, this is more and more common in the $13-$24k commuter and entry level car range as well. I'd much rather that TPMS or backup camera system be omitted, and maybe they spend that money on better materials for the steering wheel, or some additional sound deadening, or upholstery that does not feel like its been woven out of something that grew out of my back.

 

Some kind of tire pressure monitoring is mandatory (as of Sep 2007), you can thank the media's reaction to the Ford Explorer/Firestone debacle for that.

The cheap system uses wheel speed sensors. A tire that's low on pressure has a smaller radius, therefore it turns faster than one that's got the correct pressure in it. This works reasonably well for detecting one tire that's going flat, but it's not so good at detecting 4 tires that just haven't been topped up in ages and are all leaking at the same rate.

The direct monitoring system covers more cases and is more sensitive, but also more failure prone. That said, the bugs seem to have been largely worked out of it by now, and it's not a big deal for most for most people who don't buy multiple sets of wheels and who drive the car often enough to run out of tread before they run out of battery power.

--Ian

(Edit: was just reading the wikipedia article about TPMS and apparently the "wheel speed sensor" systems can actually detect simultaneous lowering of pressure on all four tires by looking for particular oscillations and vibrations. Crazy.)

 

 

Great. So now I have to stick with pre 2007 cars.

I thought I read somewhere that the OEM systems were actually setup to detect temperature rather than pressure, due to the fact that a tire will run hot when low. Is that not the case anymore?

 

The direct TPMS systems (the ones with radios) send both temperature and pressure. Indirect ones (wheel speed sensors) don't send either.

Indirect TPMS is pretty much invisible unless you want to run staggered tire diameters or something stupid like that.

--Ian

 

which cars run indirect? I've never even heard of that. always thought all of them were direct

 

Our 2007 Odyssey was indirect. Unsurprisingly, expensive German cars got direct, cheaper Japanese cars usually went indirect.

--Ian

 

Ok, so TPMS I can see, but what about all the other stupid options? I also loathe that they force you into this stuff with options packages. What ever happened to the days where you could buy a car without a stereo?

...and now I daily a 2004 WRX.

 

And for only $4,000 more, I coulda yanked the stereo out for you. You shoulda asked.

 

One of the problems with trying to retrofit the higher spec lights on a base car is that a lot of the time now it will have completely different wiring or even completely different modules. Or the lights will even have a module inside them. When I connect the scan tool to a GM product and do a full vehicle scan for codes it'll ask me what lighting options it has so it knows what modules are installed in the car. Also the only problems I really see with in tire tpms sensors are the batterys failing in them and needing to be replaced (gm) or aluminum wheels corroding around the valve stem then leaking (toyota). Gm doesn't make the metal stem ones anymore so if they fail you replace them with the rubber stem ones. I think its pretty nice to have except for the gm ones have to be reprogrammed after every tire rotation.

 

vlad, your wife's Mazda6 is indirect, as are all current Mazdas. GM uses direct in pretty much everything. The honda pilot is direct. my VW wagon was indirect.

G, the big reason they force you into other option packages is that they try to bundle popular things together to streamline manufacturing. The fewer iterations you have to build of a vehicle, the less you have to change things up and waste time and money. It's annoying. BUT on the bright side, you often do get each feature for less.

Example: On most Mazdas, the moonroof is paired with the Bose stereo. I'd often have people complain about this. But when you point out that they're only paying $800-1000 (invoice) for BOTH features, suddenly it's way more palatable.

 

o rly? didn't know that. cool, I guess.

 

Hmmmm, my hardtop didn't come with a moon roof

It's nice to know that there are rubber tire sensors now, instead of the screw(you over) together aluminum ones.

 

Yeah, it's all about controlling costs in inventory management. It's much cheaper to only make a few versions of the car.

I'm sort of keeping an eye open for DIY hackable direct TPMS sensors. I'd like to install them in my R comps so I can datalog tire pressures & temperatures on track...

--Ian

 

Yep, TPMS has been required since 2007. Backup cameras are required starting in 2018.