Hello,

I've been having some really strange issues with my tire pressure monitoring system and I'm stumped.

Symptoms:
Upon turning the vehicle on, the tire pressure warning light flashes on and off for a minute or so before staying illuminated continuously. In Techstream, using the data list function, I can see that 3 sensors are reading but one is not. I also see trouble code C2126 (Transmitter ID not received) that I cannot clear.

Background:
Issue has developed over time. At first, the TPMS light would flash intermittently, usually during cold weather. It became more common slowly, and eventually became continuous. I suspected that one of the sensors' battery had died, and as part of a recent tire change replaced all 4 sensors with new OEM ones. The tire shop tried but could not program the new sensors, so I used Techstream to program the new sensor ID's and it indicated the the ID's were programmed successfully. The data list function confirms that the new IDs are entered.

Attempted Solutions:

• I attempted the TPMS reset button (under the dash) multiple times, but the ECU does not seem to enter the initialization mode. Based on this service bulletin I found (L-SB-0077-13), the light should flash 3 times and then turn off, but for me the light does not turn off and keeps flashing (same behavior as if I hadn't pressed the button).
• I switched the order of the ID's in Techstream and reprogrammed them. Originally, the #2 sensor was not reading, but after switching its ID with #3, the #3 sensor is not reading and the #2 is reading fine.
• Using one of the old sensors that I know were previously working, I tried to program in that ID in place of the ID that was not reading, but I still got no data. I know that the old sensor was working, even outside the tire, from before I programmed in the new IDs.
• I tried using the signal check function in Techstream to potentially get the ECU "unstuck", but this did not resolve the issue or provide any meaningful data. However, I might be doing this incorrectly, as I couldn't find any consistent guidance on how to do this.
• I disconnected the negative terminal of the battery for an hour with the headlight switch in the on position in an effort to reboot the TPMS ECU but this did not work.

Other Notes:

• Occasionally, when trying to program new sensor IDs (as I've tried this multiple times over the past few days in an effort to resolve this problem) I get an error stating that Techstream couldn't communicate to the ECU as it was in initialization mode. This leads me to suspect that the ECU is somehow stuck in initialization but I don't know how to break this cycle. I was able to get the ID's to program successfully by shorting CG and TC on the OBD2 connector using a paperclip.
• When using Techstream data list prior to getting the new tires/sensors, I was getting a reading on all but one of the sensors, same issue as I have now.
• I am using a VXDIAG tool with Techstream version 18.

I suspect one of these causes, but I'm not sure what diagnostic steps to take next:

• Bad TPMS sensor. However, this doesn't explain why I couldn't get a reading from a known good sensor. Also, the problem is similar to what I saw before getting the new sensors installed, and I'm skeptical that a brand new OEM sensor would be broken out of the box (although it is a possibility).
• Some sort of wiring issue. Maybe the wiring for the TPMS reset button has an open circuit?
• Damaged TPMS receiver/antenna. But, if say the #2 antenna was damaged, then switching the ID's around in Techstream should always lead to #2 not reading (but it didn't). Maybe the ECU has some weird way of assigning the IDs to antennas regardless of the order that they were entered?
• Signal integrity problem or some sort of interference, but I tried in multiple locations to no avail.
• Issue with the TPMS ECU itself, or some kind of software glitch.

Any advice or suggestions are greatly appreciated. Thanks in advance!

 

Drive to a Discount Tire and tell them your TPMS light is on and can they check to see if you have a bad sensor. They have a handheld TPMS device and in 30 seconds can tell you if your TPMS sensors are transmitting or not. This will confirm or eliminate the possibility of having a bad sensor.

This is a free service they offer and you won’t even have to pull your car into a bay.

Let me know what you find out. I have the exact same car and you were smart getting OEM sensors. I’ve heard aftermarket can be temperamental.

Pete

 

You shouldn’t push the button under the dash until the new sensors are communicating with the ECU already. Do it too early and the system will lock you out and you’ll need a tire scan tool or program that can unlock the ECU. That being said I’ve never seen that problem with a GS but never had someone play with the system that much before I got to it.

where are you located ?


https://www.dillvalves.com/wp-content/uploads/TPMS-PDFs/Relearns/RL-A1239.pdf

 

Here's an update:
Discount tire found that one of the sensors was not responding. I had them swap it out with one of the good old sensors for now (will try to return the bad one to the eBay seller). They were able to reprogram them and the TPMS light is off, but the pressures are still not reading on the dash display (still shows dashes in place of measurements). They are reading fine in Techstream.
I tried doing the TPMS button under the dash (with IGN ON pushed it until the light flashed 3 times, then released it and waited a few mins, then drove around for a bit) but it still won't read.

Where do I go from here? Is there something I need to do in Techstream? Should I try shorting the TC and CG on the OBD2 again?
Thanks for the help!

 

if you have at least 1 low or weak battery your probably going to have dashes when it gets cold out and eventually all the time. I’m going through this right now and just waiting until I replace the front tires. I have 2 new sensors in the rear and old ones up front on my 13’ GS. Sometimes I get pressure and sometimes I don’t. On trips I’ll get the occasional flashing light.

 

Funny I started to develop weird issues with my system too. (2015).
The pressures were low on all four tires so I put air on all four. Next time I was driving, the numbers disappeared and became all dashes and the yellow light started flashing. The next day, the readings came back. Two days later, yellow light flashing and dashes again.

 

Thanks everyone for the info, and good to hear that it’s not just my system that is having problems. My best guess is that there’s something up with the part of the system that determines the location of each tire, either on the sensor end or on the receiver end (I came to this conclusion because I can see all 4 values fine in Techstream). I live in a colder climate so it could just be snow or ice somehow interfering with the receiver and/or cold temperatures causing low voltage in the TPMS sensor batteries. I’ll see what it’s like when temperatures get a bit warmer and hopefully the issue resolves itself.

Thanks for all the assistance everyone!

 

if one of the sensors is bad, it will only show -- for all tires instead of showing the PSI numbers. it happened to me last week, I went to discount tire and ask them to scan which sensor was dead and got it replaced, cost $64 and everyting is normal now.

 

2 of mine are on their last leg. Dashes when it’s cold and I’ll get the flashing light on longer trips.