Suspicious TPMS data?

[gregd]

Hi folks,

My Roadster 2.0 goes in for its annual maintenance tomorrow, and I'm thinking of asking them to check out the rear TPMS system.

I have an OVMS module installed, and noticed that almost always the rear tires read exactly the same pressure and temperature. The fronts are nearly always slightly different from each other, both in temperature and pressure. The VMS display of the tire parameters shows the same behavior, though with slightly less precision.

It seems to me that there's something odd going on with the rears, but I can't imagine what sort of condition would cause it, since each tire has a unique ID, and the car should record each tire individually. It's not like there's a crossed or shorted wire somewhere that could cause this. And, that the numbers do occasionally differ, suggests that the data is, in fact, live and independent.

Any thoughts? Is this worth bringing up with the service guys, or would I be wasting their time? I know I could let some air in/out of one of the tires to check, but it's late, and there may be more going on here than a quick experiment could determine...

 

[ShawnA]

Hi Greg,

I have communicated with Scotty on various TPMS issues.
His problem was after time something was corrupting the addresses in the antennae.

He has made some intriguing yet odd discoveries...
Both front and rear antennas have all four tires addresses in each of them...

If the front antenna has all 4 addresses correct the system will work fine even if the rear antenna is corrupt.
The reverse is true it the rear antenna has all 4 addresses correct the system will work fine even if the front antenna is corrupt.

When the addresses are corrupt in both antennae - the car is screwed and will issue the dreaded message.

From Scotty's instructions I was able to successfully program the rear antenna and got the system working with
a full set of new sensors.

I used a tool to get the addresses and I used Scotty's hack to set them in the rear antenna.
I used the rear antenna because it was easier to access.

While doing this I noticed that all of the plain steel fasteners holding the bottom pans were badly rusted.
I replaced them all with 316 Stainless Steel.

So after the long history - Tesla can do their quick scan and program routine and you should be good to go.
Their tool also checks sensor voltages so if they are on the way out it might be a good time to replace them.
I used a Dill 2112 sensor for replacements.

Good luck,

Shawn

PS Do you have a zany aftermarket radio of some sort?
Scotty still has not figured out what is corrupting his addresses...

 

[gregd]

Ah, right. Corrupted addresses... So this is a long shot, but if one of the antennas had all 4 sensors correct, and the other had the back tires swapped, that could explain the symptoms, depending on the sequence of updates.

The main Roadster tech wasn't doing my car today, so I didn't bring the issue up. Will monitor more closely, and see if a pattern develops. I wonder, do the CAN bus messages on the diagnostic connector (the one under the passenger dash) include the sensor ID? I'm thinking they don't...

 

[ShawnA]

Hi Greg,

Mine seems to function OK with the correct addresses by Scotty in the rear antenna.
The front antenna has 4 different addresses - the old sensors - and the car ignores them...

I have never been able to retrieve addresses from the car by CAN, K-line, or LIN
while the antennae were still mounted in the car.
They are easily obtained by a TPMS tool that will read 433 Mhz sensors in the tires.
They are easily read by virtually ALL TPMS tools.

I am still working on an ATEQ VT55.
Ateq is still seeking protocol information from Tesla to add the OBD2 ECU update
to the VT55 and their other tools.

You may want to request a listing of your addresses from the technician
when he reads and updates them.
They would be good to have if Scotty or others come up with an alternate solution.

Shawn

 

[gregd]

Thanks for the update, Shawn.

It looks like I will be needing new tires some time this summer. It will probably be best to address this situation at that time.

 

[markwj]

I wonder, do the CAN bus messages on the diagnostic connector (the one under the passenger dash) include the sensor ID? I'm thinking they don't...

Nope.