I have a TPMS issue with my Aspen. The backstory is it had dead and mis-matched sensors and the dash light on and no pressure readings from 2 sensors when I bought it. Bought a set of 4 new after market sensors and installed. I cleaned up the valve stem holes and wheel lips to solve my slow leaks as well. Within a few minutes of driving SHAZZAM! they all read and all was wonderful for around 1000 miles. I thought i had matching tires but found i did not. The Aspen had 2 new Pirelli Scorpion AS tires on the front and a slightly older series of Pirelli Scorpion Verde on the rear, about 2years by date codes. I bought 2 new matching AS series for a matched set of 4 tires. This is where things went off the rails. I watched the process through the window into the shop. They pulled the front wheels off and re-balanced. The wheels were returned to their original locations L/R Front. The rears were broken down and new tires installed. I lost track of these two and am not sure if they were put back to their original L/R locations in the rear. I figured no harm, a few miles and things will sort themselves out. Instead, now I have pressure readings that are criss-cross and don't follow the wheels. When I went to the tire shop all my sensors read 32PSI. Now I read 32LF 34RF and 34LR and 32RR. I think my originals are the 32PSI and the new tires are the 34PSI.

No CEL or TPMS light but when I look with my scantool (Launch X431) it has a fault code that TPMS cannot read tire position C151D in the WCM Module. This follows what I see with 32/34PSI. I do not know the sensor IDs and do not have the equipment to read them. It appears I can force a sensor ID to program into a certain wheel location but I have no values to enter. Does anybody know how to get the system to RESET or suggestions to solve my mis-read location issues? Will this happen with every tire rotation service in the future? Anybody else found the system to be finicky?

I was also wondering how the system picks up the sensors? Are there receivers near the wheel locations or how would the system auto-read new sensors... Any additional insight would be appreciated.

 

Question I have is are you checking the pressures manually with a tire gauge or just going by what the sensors are saying on the EVIC? The sensors can have a margin of error. Although they all may have read 32 psi at the shop, once you drove on them, the pressure could have changed due to temperatures. The system also updates pressures as you are driving above 15 mph for 10 minutes. Therefore, it may not have read correctly when sitting still, but then updated to actual pressures when driving.

I have no idea how the system determines the location of each sensor. Been trying to figure that one out myself. From what I have been reading and watching on videos, you need a special TPMS scan tool to get the sensor ID's and then another special scan tool to program. Although you have the tool to program, you don't have the reading tool. However, per the TPMS reset instructions, this is not required.

Per the reset instructions for TPMS on Aspen, it recommends airing all tires to the proper placard pressure (door label) using a manual tire gage. Better to use mechanical gauges than electronic as they are more accurate. Leave the vehicle off for 20 minutes. Then drive the vehicle over 15 mph for at least 10 minutes. The relearn process may take 10-35 minutes of driving. The vehicle will relearn the sensor ID's. Then manually check the pressures again with your gauge to see if they match each location displayed on the EVIC. They should be very close. Even then, I often see some slight variances. Again, the sensors are not perfect and temperatures can change the pressures from start to end. They are just an added safety precaution.

To make sure they are reading in the correct location, try adjusting the pressure a little low or high on one. I generally run mine at 35 for better tread life. So for example, put one at 32 and the rest at 35. Drive for 10-35 minutes and see if it displays in the correct location. Then put back to correct pressure. Repeat for each tire. This may be a long process, but at least you will be sure the locations are correct.

If the above does not get you back to normal, you may want to do a full reset of the system by disconnecting the battery overnight. Hopefully this will trigger a full relearn of the sensors.

 

Thank you for the reply.

The only thing about the pressures themselves was I had set them all cool, in my garage and all were shown equal upon arriving at the tire shop. The tire shop equipment would of course be slightly different, which helped me deduce that the two slightly different pressures seen immediately pulling out of the shop, were from their influence and the two new tires. Then the scantool provided the C151D error where it was unable to determine correct location. The error has remained in a status of "active" and immediately returns when trying to clear it.

Since I have been chasing down several small "gremlins" since starting my ownership and rehab of the Aspen in May and over the last 3000 miles-ish, that code is a new one I have not seen it before now.

I think I will try the over night battery dis-connect option and see if things normalize (easiest route). If not, I believe the tire shop (Discount Tire) has the tool that will read individual IDs and then note them to try and force locations. I also thought of trying to force program a made up/BS ID number into the 4 positions as a type of reset and see if the truck can then recognize and relearn the sensors correctly.

My Google searches too, have turned up no information on how it sees the sensors and determines their location. I have looked in the wheel well areas for some sort of pick-up device but have not seen anything.

 

Yeah, gremlins are difficult to pin down and with everything going electronic these days, they are only going to get worse. I have a few myself on mine. Keep us posted on what you find and if you get it figured out.

 

I did find a solution. I went back to Discount Tire this morning. They read the sensor IDs with a Bartec tech 450 Pro tool and I wrote down the IDs for my own record. Then they plugged into the OBD port and wrote the sensor IDs to the correct locations, FIXED. It is always easy with the right tools. I still do not know how the vehicle picks up the sensors and determines which wheel position they are in... Just me but i like to know how things work.

 

Right tools do help. Glad you got it fixed. I too would like to know more about how it determines which is which. I mean, if you rotate tires front to back, does it know this and changes the position on the display or just displays incorrectly. Very curious..