Learn Me TPMS Calibration: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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Dec. 14, 2010 6:17 p.m. JohnyHachi6 New Reader

Did a search and didn't find a thread specifically about this. If there is one; my apologies.

Here's the issue. My girlfriend took her 2006 RX-8 into a tire shop (Firestone I think) to get some new street tires this last Sunday. (Kept the same wheels and TPMS sensors, changed out all 4 tires.) I told her to make sure that the TPMS light was off before she paid and took the car home, but when she went to pick up the car they told her that the light was on and would go off after driving for a few miles. So, Monday (yesterday) morning she drove the car in to work and sure enough, the light went off. So far so good?

However, this morning while she was driving to work the light came back on but was flashing, which the manual indicates is a fault in the TPMS. Since then we've driven the car to run a few more errands and it has come on flashing one other time - seems to only happen on longer (20+ minute trips).

She's taking it back to the shop tomorrow and they're going to take a look at it but they said it might be something that has to be fixed at the dealership and I'm dubious.

I'd like to know what is involved in the TPMS calibration/installation process and how the car knows which TPMS sensors belong to which wheels, etc... and what the shop SHOULD be doing when they change the tires.

FYI, it looked to me, based on the amount of brake dust on the rims, that they switched the wheel location front to back when they replaced the tires.

Thanks guys!
Dec. 14, 2010 6:20 p.m. Auto ADD Dork

First mistake was going to Firestone. I have had nothing but problems when I used them in the past.
Dec. 14, 2010 6:50 p.m. triumph5 Dork

I know zilch about the internal workings--other than they're RFIDed--of these, but wonder if they are direction sensitive? Could it be moving a rim from one side to the other has upset the internals? Which leads to, do the driver's and passenger's side have different part numbers?
Dec. 14, 2010 6:55 p.m. wlkelley3 Dork

Have the same problem with my 04 RX8. TPMS light starts flashing after driving long enough to warm the tires up. Dealer looked at mine and said a TPMS sensor on an axle is damaged and would cost around $200 to fix. With the dealer here, that would be at least that much. I just put up with it flashing. Less bothersome when you know why but still irratating.
Dec. 14, 2010 6:56 p.m. RexSeven Dork

If the TPMS system is the same as on my Speed3, then the TPMS sensors should be detected and the (!) light should turn off after 5-10 minutes, as long as the tire pressures are in the specified range. Since the light is not turning off, that most likely means one of the sensors is damaged or installed improperly.
Dec. 14, 2010 6:58 p.m. mith612 Reader
Mitchell OnDemand: TPMS RESET

NOTE: Whenever tires or wheels are changed (such as changing to and from winter tires), the tire pressure sensor's unique ID signal code must be registered with the TPM system.
1. Turn ignition switch to ON position, then turn it back to LOCK position.
2. Leave the vehicle with the engine off, and wait for about 15 minutes.
3. After about 15 minutes, drive vehicle at a speed of at least 15.5 MPH (25 KM/H) for 10 minutes or more. Tire pressure sensor ID signal code will be registered automatically.
NOTE: If vehicle is driven within 15 minutes of changing tires, the warning light will flash because the sensor ID signal code would not have been registered. If this happens, park the vehicle for about 15 minutes, after which sensor ID signal code will register upon driving vehicle for 10 minutes or more.
Dec. 14, 2010 7:25 p.m. Ranger50 Reader

I would guess that one or more of the sensors got cracked taking the old tires off. Therefore, it broke and is rattling around in the tire. Most of the decent tire shops should have a TPMS sensor tool to trigger them on. The one that doesn't register is broke.

Brian
Dec. 14, 2010 7:39 p.m. tuna55 Dork

I worked at TRW and was an engineer when these systems were developed for Honda, Ford, Hyundai/Kia and GM. Mazda was not one of of them, though, so this may or may not apply.

Depending on OEM requirements, there were high line and low line systems.

A high line system had an initiator at each wheel well with a short range coil which would prompt the sensor to wake up and tell the BCM what the ID was. In this way, you could change sensors, positions, or anything else, start the car and it would figure it out itself. My boss at the time was working on a high line system with no initiators which would use signal strength and some work done at the factory to decide how much signal degradation could be expected from each position, but it seemed a long way off, and I doubt that technology is being employed currently.

A low line system skipped the initiators, and just had the sensors and the BCM. The sensors would scream if they got a low signal and the BCM would just say "hey driver, I have a flat... somewhere". Obviously, this type of system wouldn't care where the sensors were either.

Now, if the sensors were changed out for new ones, there is a procedure for teaching the BCM which sensors to look for (I think) in the low line case.

Again, your car may be entirely different, especially if they weren't made by TRW. I left in 2005, so who knows?

The procedure posted a few posts up which tells you to drive the thing after wiggling the right way rings a bell for turning on the new sensors, but that really should be only with NEW sensors, unless the system wasn't designed as well as what we sold was.
Dec. 14, 2010 9:05 p.m. JohnyHachi6 New Reader

Thanks for all your replies. I ran through the procedure that is needed when new TPMS sensors are installed (even though the old ones were used). Here's what I found: After driving the car for a total of exactly 10 minutes at speeds over 15.5 mph the TPMS light comes on blinking. This is happening repeatably and always after 10 minutes to the second. I assume what happened is that one of the sensors was damaged and is not transmitting, so the car spends those 10 minutes looking for a signal. After the 10 minutes with no signal found the light comes on to indicate a fault.

It's pretty clear that the shop damaged the sensor during the tire change so we'll see about having them replace it.

Thanks again for your help - much appreciated.
Dec. 14, 2010 9:15 p.m. tuna55 Dork

JohnyHachi6 wrote:

Thanks for all your replies. I ran through the procedure that is needed when new TPMS sensors are installed (even though the old ones were used). Here's what I found: After driving the car for a total of exactly 10 minutes at speeds over 15.5 mph the TPMS light comes on blinking. This is happening repeatably and always after 10 minutes to the second. I assume what happened is that one of the sensors was damaged and is not transmitting, so the car spends those 10 minutes looking for a signal. After the 10 minutes with no signal found the light comes on to indicate a fault.

It's pretty clear that the shop damaged the sensor during the tire change so we'll see about having them replace it.

Thanks again for your help - much appreciated.

Bingo!
Dec. 15, 2010 10:36 a.m. Hal Dork

Just to add some info to this thread:

If I swap the wheels on my Transit Connect from front to rear I have to go thru a training procedure to tell the computer module which wheel each sensor is located on. This is because of the differing tire pressures 36 front, 49 rear.

Since the sensors can be used with widely differing tire pressures. This leads me to belive that the only way I am going to be able to run lower pressures in the rear is to get someone to reprogram the computer module that monitors tire pressures.