A Modest Proposal To Solve The TPMS Problem

OK, I'll bite...

...why don't you like TPMS?

 

I don't think that would work since the sensor doesn't pick up any pressure. You'd have to put a sensor in a sealed PVC tube and pump it up with some pressure and keep it in the car somewhere.

 

The bag isn't pressurized, so won't the warning light stay on?

 

You beat me to it!!!

 

^^ Hehe I had to do that on my friends car since he upgraded his wheels without adding TPMS sensors so I experimented and it worked.

 

Black tape to cover the light? Not to elegant but it would work.

I don't understand how putting them in a plastic tube and pressurizing it works. I thought they operated on a differential pressure system that senses the pressure on the end that goes in the tire and compares it to the pressure on the outside end. Seems like you would need to drill holes in the tube and insert them so you could pressurize only the end that normally goes into the tire.

Or is that how you did it? If so were there any problems with leaks due to the curvature of the tube? I have thought of doing this also but I figured it would leak and end up alarming all the time.

 

Uhh...

might I point out that if you ever get into an accident due to low tire pressure... and your insurance finds out that you've tampered with the TPMS, then they can deny your claim...

You can also try this: black electrical tape over the warning light.
Recalibrate the TPMS sensor (not sure if its possible on the G3 prius)

 

You might be wrong about this Bob?

My impression from talking to people in the insurance business is that they are required to cover you if you are insured and have an accident, no matter what you have done that might have caused it. I think they would be required to cover me even if I were drunk or going 10 times the speed limit. After it's all over they may be able to raise my rates or even cancel me but they can't always do that either. Rates and reasons for cancellation may be dictated by state insurance commissions and differ from state to state.

I think if insurance companies could refuse to pay a claim because of bad behavior or nonfunctional safety equipment people would have a pretty hard time getting cars financed. The financial institutions would not want to put their capital at risk without insurance to back them up in case the car were damaged or destroyed.

 

According to someone on the internet:

 

TPMS uses absolute pressure sensors. In other words, the pressure sensor has a sealed chamber that is used as the reference pressure. A differential sensor using outside air pressure would be subject to contamination from dirt, water, salt, and other nasties.

Because of the sealed reference chamber, putting the TPMS valve stems inside a pressurized pipe works just fine.

Tom

 

Isn't there a way to reset the TPMS to use a different pressure as the baseline? Pretty sure there is, and you could deflate all your tires, set the new baseline, then pump them back up again.

(yes, this would fully qualify as "tampering".)

You can do the opposite if you run your psi higher and want to be notified when they lose even a little pressure. I think the spread is 8psi, so when the current pressure is that far below the baseline on any wheel, the light comes on.

I prefer to just ignore the light when my snow tires are on - and since snow tires perform SO far beyond the stock tires in the winter, that's more than an offset for the loss of TPMS (and I check pressures manually, so the insurance co would have to suck it up anyway). It would have been $350 to get a second set of sensors installed, and another $50 twice per year (and a f*cking PITA) to reset the system to recognize a different set of sensors.

And yes, I have had a flat on the regular tires and didn't believe the TPMS light when it first came on - but that plus the huge drop in MPG in the first mile convinced me that there was an issue, and probably saved my rim.

 

OK thanks for the information Tom, that looks like a good way to get rid of the yellow/orange light then.

Of interest, there are much better ways to design the system.

I looked at an Audi recently, if you install a new sensor or all new sensors (such as with snow tires) all you have to do is drive the car down the highway for 30 minutes without stopping and they system will register the new sensors and use them. They also have a way for the driver to reset the system if you want to use different pressures, as we do.

BMW also had a good system that didn't use pressure sensors at all. It looked at the difference in wheel speeds using the ABS speed sensors and when one wheel was slower than the others for a period of time it warned you of a possible low tire. I'm not sure if they still use that system or not.

On the other had I understand that owners of new Hondas have a lot more trouble with TPMS than Toyota owners. Their system reports over pressure as well as under pressure and there is no button for the driver to reset the thing. I ask a Honda service manager at a dealer near here, he said they are set for factory recommended pressures. He did say that for a price (I didn't ask how much) they could hook up the computer to them but could only change them about 6 pounds. I'm not sure what Insight owners that want higher tire pressures do, maybe they have a different system for the hybrids but I don't think so. I was considering a new Ridgeline pickup but the TPMS problems on the Honda owner sites scared me off, there may be a Tacoma in my future.

 

Yes it's easy to do, owner's manual page 442 & 443.

 

Then there's no need for the pipe bomb approach...

 

I don't think you can reset the system to 0 psi so if they are not in a tire or a "pipe bomb" the system will still be in alarm. I haven't tried it though.

 

I had that system in my last car (BMW). It was not a TPMS, but rather called a flat tire monitor. It was much less sensitive than a TPMS, so not a very good system in my estimation (I had the light come on and I pulled into a gas station immediately, and was 25 PSI low), and was replaced in subsequent years by a true TPMS, as required by US DOT.

 

I am thinking of getting getting four new rims for snow tires. Then I will put three snow tires on the new rims and put one on an old rim with a sensor. This way, in the summer three tires will have sensors and in the winter only one will. The warning light should not come on.

Do you think this will work?

Chris

 

I don't think that will work. The system knows when only one tire is low on PSI, so I would think that ALL the tires have to be there. If a signal (tire) is missing, then you'd probably get the TPMS light. I think it's 4 PSI on my 2007.
I know from one of the Corvette guy's here at work that if the Corvette sees a messed up TPMS signal, the engine will not go in to the performance mode. Corvette owners often use the PVC pipe method, and just put the sensors in there and have a tire valve on the pipe to pump it up. Pipe goes in the trunk. Then you can have all sorts of custom rims - the ones with racing slicks on them, etc. - and the TPMS does not interfere with engine performance