Add this one to the TPMS lore file.

Hello friends,

I recently had a "fun" experience at a local tire and wheel joint with the TPMS system in my 2009 Tacoma. If you don't want to read the whole story, the solved issue and explanation is at the very bottom of this post.

I went in and purchased 4 new winter tires for a set of steelies that didn't have TPMS installed. The price was pretty dang good and papa was feeling his oats, so I asked how much for 4 new TPMS sensors along with the skins. (Frivolous detail: I have had my eye on one of those magic summer/winter TPMS change boxes and wanted an excuse to get one. Now I have two sets of wheels with TPMS sensors, so I obviously need to get one.)

There was a brief bit of grunting, eyebrow waggling, hairy fingers punching calculators, and gesticulating, and so they went ahead and put those in for me. An astonishingly short amount of time later, off I go and the TPMS light is still on. I gave it a few minutes on the big road, just to see if any ghosts needed to be let out of the machine, and then turned right around and went in to let them know about it. The gentleman at the front desk consulted with a tech, who said it was normal and that if it didn't turn off by the time I got home, to come back.

For the record: I genuinely didn't feel like dealing with it that day, and chose to believe them despite knowing that the flashing TPMS at startup meant there was a system error, not simply a fault indicator.

The next day, I decided to see if there was any chicken waving I could do to learn about the TPMS system in the truck. I turned it off and on, played with the TPMS button, thought very hard thoughts about radio waves, and then on a whim decided to go check the tire pressure in the brand new just-mounted tires.

"Aha," I thought to myself. "If I catch the dumb mistake now, I can be my own hero, and not the jaggoff in the mini monster truck who doesn't even know how to check his own tire pressure."

Tires 1-3 were exactly where they should have been. Tire 4 had an extra 15 PSI in it, so I let them out to be with their friends in the atmosphere. Some of you have already guessed what happened next - the *#W%$^(@#$% TPMS light blinked system error at me and then went solid as I drove back to the tire and wheel.

I watched another tech perform an exactly perfect TPMS relearn procedure on my truck with 4 (four) different machines. At one point, he came to me with a tear-stained, grubby-fingered LCD display to show me that the computer swears it's done. The only thing they can do at this point is tear the tires open and put four new TPMS sensors in.

I didn't have time, so I went back again a few days later early in the morning. When I walked in the first thing the guy asked me was if I wanted a refund on the TPMS and to have the new sensors put in immediately for free. Well, this time I DID have time, and I was very curious to know what was going on so I could file it away for next time. I suspected that they were using shite sensors as sales tools and I'd just been bit by it, knowing what little I do about aftermarket TPMS.

I watched on the screen out front as they got the truck in and got one wheel off and popped open to do the surgery when they stopped, put it back together, back on the truck, and then disappeared off the rack with the truck. I waited and waited and waited for the truck to appear out front so they could tell me "here's your refund, go away".

Eventually, the truck pulled up out front and parked. The manager walked out and I clearly heard him ask "Did that fix it?" with a very interesting expression in his voice. The tech bunched his eyebrows over the mask and gave a fast, sideways nod. It looked.... sketchy. I was not amused. I really wanted to hear the explanation, so I busted ass out the door as unobtrusively as possible to hear it. I needn't have bothered, the guy looked at me and said, "Check this out..."

My 2009 TRD OR AC is registered as, was sold as, VIN comes back as a 2009. Production date was 05/2008. It would appear to have an ECU that thinks it is a 2008 model year. As soon as the tech had the idiea, he plugged model year 2008 into the first machine to hand, and performed a TPMS relearn, and it worked exactly correctly the first try after failing dozens of times with multiple machines.

Is this a situation that is well known? These guys do about a billion TPMS relearns a month and had never heard of it happening.