LED's and Tpms

From your description, I'd guess TPMS batteries (they do fail!) That, or try new dealer? Sorry I can't help more, but I'm sure there are others here who are sure to know exactly what your problem is! Good luck!

 

When the dealer hooks up to the car with Techstream, they can see the ID of each sensor, its battery status, the pressure and temperature it's reading, and the reasons for any time the TPMS lit the warning light. They could show you all that right on the laptop screen. Weird that they'd want to give you the impression they've got no information and swapping parts is the best they can do....

-Chap

 

No signal from anything, yes, that does suggest radiofrequency interference. You could consider bypass capacitors / ferrites / etc. on the wires serving the lights where you've installed LEDs.

Are the LEDs you're using actively regulated (if you have a variable voltage power supply to feed them with, and you sweep the voltage up from, oh, 10-ish to 14-ish, do they stay about the same brightness and decrease their current draw)?

I've never experienced an LED by itself being much of a source of noise, but cheap switch-mode regulators certainly can be.

You'd probably want unregulated in a Prius anyway, at least for the cabin lights, so the glamorous fade-up/fade-down doesn't get defeated by the regulator.

-Chap

 

The likely cause?

 

This is strange case I do not think we have heard any similar issue.

There are of course 2 elements to the TPMS system - (1) the 4 tire sensors, and (2) the receiver/logic unit in the car.
The vast majority of our discussion concerns the tire TPMS sensors, and they last a long time normally. Mine are going on 11 years old, and so far only one battery has failed in one tire. If one does break or goes bad, then the light comes on. Techstream should allow finding a bad unit. Gotta wonder if somebody is missing a bad TPMS.

Possibly the receiver unit had gone bad, which I don't recall ever hearing that before. One of our members here on Prius Chat got technical and figured out how to send code to the receiver unit to change the number of TPMS to 5 from 4 so he could check the spare tire pressure. Also there have been some hacks on the wiring mentioned on some websites, if I recall, to turn the warning light off. A wire could be misplaced in a insert socket somewhere.

 

My hunch is the tire shop messed up something.

 

Sprayed/soaked the sensors along with the wheel with lub. when installing the tires?

DO check that the LEDs are linear, not switching type. If there is no chip on the board, just a resistor or two then they are linear and won't cause any problems.

 

The only thing I can think of:
let's say you have the code set to a spare tire sitting on the garage floor, and that tire is low pressure.
So then when you pull into the garage the receiver picks up the signal and tells you its flat. This is basically what I do intentionally (with a good pressure) to turn my light off, even though I have one bad one. Actually I use a variation of that idea, but it works.

If I recall (check me on this) the Gen3 receiving unit may be located above the driver side door on the roof (inside) so I don't know if your LED work got into that area for some reason. Gen2 it was located near the dash which one might expect.

 

Black tape worked for a week until my wife saw what I did!

 

I am not sure this might be related but did the tire shop reset the TPMS after new tires were put on? I know for my 2005 Sienna, it uses the ABS sensors to measure the wheel revolutions. When my van got new tires, the shop forgot to reset the system so my tire pressure warning light kept coming on. I reset it and it did not come back. I am not sure what the Prius manual calls for after the tires are replaced.

 

It is very strange, that even with all the parts swapped out, the system STILL is not working.

What's goofy, and as a card carrying lapsed cargo cultist I have to note: there is nothing functionally wrong with the car, with it's ability to get you places and so on. All this hair-pulling consternation is over a system intended to detect problems, lol.

 

Planning to try replacing it with a shielded one?

-Chap