Which brand sensors were the troublesome ones, and what were the replacements that worked?

 

Excellent technical description.

 

they were all OEM gm units as far as I was told, but I can't actually know that for sure but I have no reason to think they were lying
it's been I think 5 years now and not one issue ever since

 

The actual technical terms are not permitted on Corvette Forum.

 

I drove the car some this weekend, after swapping the L and R fronts around and what do know, the front passenger would not read. I think it’s evident it is a single issue with the passenger side.

Have you moved any antennas yet?

 

Yes, you have the same problem as me.....

Not yet, I will be able to start doing this in about 2 weeks....

 

Im curious to see how that goes.

Do you know where all the antennas are? I’m seeing info saying that there is one in each door and a couple behind the dash but i can’t really verify that. I don’t mind pulling door panels but im not crazy about tearing into the dash.

 

Antenna locations:
1) behind the radio & climate controls
2) just behind the center console storage compartment/armrest, on the rear bulkhead wall.
3) behind the left rear wheel well liner (this is called the left door sensor in the GM service manual, but it is not in the door)
4) behind the right rear wheel well liner (this is called the right door sensor in the GM service manual, but it is not in the door)
5) rear cargo area floor, near the rear fuse/relay box, under the removal access floor panel
6) mounted on the outside of the rear tub, between the bumper cover and the outside of the tub, near the rear Corvette emblem.

 

After studying the Factory Service Manual, there is more info to share concerning TPMS system components, specifically a seventh antenna.
The confusing portion of the service manual is because there are two different versions of the TPMS system.

There is a "UJM" system (RPO = XL7, 315MHz) for C7s exported to Japan, which does not have an auto-learning feature for wheel sensors. This system has 6 antennas.

The "UJN" system (RPO = XL8, 433MHz) used in USA C7s, has an additional antenna/receiver module "K65 Tire Pressure Indicator Module" (pn = 84429916), which is needed for the auto-learning feature. This K65 7th antenna/receiver module is mounted on the rear of the rear tub, behind the bumper cover. This module reads the signal strength of the sensor signals transmitted, and the signal strength is used to determine if a sensor is located in the front (weaker signal) or the rear (stronger signal). This info, plus the direction of rotation (CW or CCW) info transmitted by each sensor, allows the BCM to Auto-Learn determine the position of each wheel sensor (front Left, Front Right, Rear Left, Rear Right).

So, the bottom line is that the K65 module may also have something to-do with the intermittent inability of the TPMS system to read the signal transmitted from the front right passenger wheel.

Also, it is not clear to me which (or all) of the other 6 antennas are used to receive the TPMS wheel pressure signals. I suspect that only some of those 6 antennas are only used for the keyless entry and key-in-the-cabin detection and engine start authorization.

 

Im still not sold on moving any antennas. I’m starting to get a little bit of the red a$$ that this system is so finicky you can’t put a set of wheels you like on the car without a problem.

 

moving antennas would be crazy to try before just replacing the sensors that are acting up.
why not just do that? Take the loose wheels to a dealer and the sensors can be replaced super easy.
if you can zero in on one in particular, which it seems you have from swapping them, just take that.
I did the same thing, but mine was both fronts, and the problem was solved instantly

 

The problem with changing the brand new TPMS sensors for another brand new sensor is messing up my brand new forged wheel as a result of a tire dismount/remount.

 

I hear ya on that but it's still the least intrusive, potentially problematic move IMO. Messing with antennas might give you an endless nightmare that can never be solved.
Plus, they say (which I haven't seen but I do think is true) that you don't actually have to dismount the tire to replace a sensor. Apparently you just use the machine that does it, but only use the tool
that presses in the sidewall off the bead, giving space to access the sensor and replace it, and then just release the tire back onto the bead. I think that's what they did with mine.

Also, any shop that does large wheels with super low profile tires can mount and dismount without harming a wheel, But still, I understand why you don't want them completely removed again.

 

The shop doesn't need to completely dismount the tire to replace a TPMS. They just partially break the bead local to the TPMS and push the tire down while they get their hand in there. Pretty easy and not traumatic to the rim (assuming it's a competent person doing it of course).

 

because I've mostly ruled out it being just a sensor by swapping them. If I though that was the problem of course that's what I'd do. I've ran both front wheels on both sides of the car. They both work on the drivers side. Neither of them work on the passenger side. There's a signal issue on the passenger side. Its not as simple as just replacing the sensor.

 

Seriously TPMS was trying to put me in the trees recently. I was running a bit quickly down a twisty backroad, rounding a corner at 60 or so, and the front passenger sensor communications stopped. (Not the first time.) The car's computer took action to save me from a non-existant flat, and the vehicle dynamics instantly became totally different. I was not exactly in full control and thoughts of driving through the trees involuntarily did cross my mind.

The problem started when I replaced the original wheels. Usually tire pressure is accurately captured. But at random times communications just stop while I'm driving, and then just as randomly pick back up.

I sure hope some of you smart folks can figure this out and share a solution.

 

Yes, this is exactly what my main problem was. The tpms fail is the LEAST of the issue, it's the crazy stability control limp mode or whatever the hell it is that is the real issue.
Mine was identical. One of the fronts would go out, BAM, bizarre limp mode would trigger all kinds of interventions around corners where I wasn't even CLOSE to losing control.
It made the car miserable to drive, you literally couldn't have any fun at all without driveline interference actively kicking in to alter the course of the vehicle.

 

Just replaced my stock wheels with fully forged. Tires and new sensors mounted at the Chevy house. No issues so far. Z06

If it's always the right front wheel regardless of the which wheel is in that position, I guess it could be the antenna or perhaps a connection to that antenna or an issue within the box.

Just thinking about the wheels, I assume the sensor shoots the signal through the tire during a significant portion of its visibility to the antenna.

Interesting that the passenger front seems to be source of the problem for all here?

 

I had an idea, which isn't necessarily a good thing. But here goes anyway....

Note that this is something Chevrolet (who made these awesome cars available in the first place thank you Mother Chevy!) would have to do, if they chose to step in.

A real fix might not be developed any time soon. But a workaround could possibly be a DIC accessible TMPS intervention opt-out. Something that changes a sensed TPMS situation to remove its input to the car's control functions. Maybe there could be a flashing light on the instrument panel to let you know that there is a sensed condition, but that would be as deep as it goes. Those folks who don't want to take this path aren't forced to take any action at all.
Of course, no lawyer in their right mind would allow this to be a hard set user selected option, this would be oe of those things that returns to the default full engagement mode every time the car is turned off.
I know the mother ship has their Corvette team busy on other things, like C9 refinement. And I understand that this is critical stuff. But I see from post #19 (I think) they do monitor what we say. So if this solution is possible, please please please Chevy, could you please see if someone can break away for a few hours to scope this out?
Assuming this temporary solution could be developed, I would gladly sit in the dealership waiting room while the technicians diddle with my Z06. Christmas is coming, be my Santa......

Also, a recent post asked if the problem was just with the passenger front. In my reading of the posts on this discussion I think the answer is no, it is not exclusively the passenger front having this problem. But yes, the majority of the comments indicate this is the most common location to glitch out.

 

So i think i resolved my issue. The sensors that i use i order from a site called corvette garage.com and they advertises the part as a “GM” tpms sensor. I went back and tried to verify that they were actually the GM Shrader part number and i could not verify. I bought 2 new genuine GM sensors and had them swapped into my front wheels. I got the car out yesterday and went cruising for a while and never got the tpms alarm. So i think my issue is resolved.

Are you using GM sensors?