Backstory:
On memorial day I was taking a road trip and about half way into the 3 hour trip my TPMS light started blinking in my 05 4runner. I knew that it meant a sensor has gone bad but I stopped at the next exit just to double check my tire pressures and do a quick online search to confirm. I continued on my way.
When I got back from the trip I took it to Les schwab to figure out which sensor went bad. They pulled it in and sent em to wait inside. about 15 minutes later the tech came in and claimed that he couldn't get a reading from any of the tires and all the sensors failed and would cost a little over 400$ to replace them all. I immediately left because I knew there was absolutely no way that all 5 batteries in each sensor would fail within 48 hours of each other.
Since I have been planning to get new wheels I figured now would be a good time. So I ordered 5 denso 5500101 sensors from rock auto for much cheaper than les schwab wanted. After some research I ordered a ATEQ Quickset to program the new sensors.
Well I still don't have my new wheels yet but I have the sensors and the quickset andd the blinking light on my dash was bothering me. I figured I'd rather have it on solid saying a tire pressure was low rather than blinking. I took the quickset and pulled the codes from the OBD2 port. They were as follows:
FL:095C4090
FR:09A09090
RR:04AD0090
RL:04ACF090
SPARE:01983090
Immediatly the spare stood out to me as being different than the other 4. I was pretty sure when I changed tires previously I had also had the TPMS replaced. which would mean that the 4 on were newer than the spare and the spare was likely my culprit. So using the Quickset tool I reprogrammed it to look for the same 4 sensors and one of the new sensors that I would just keep in glove box until my new wheels arrived.
(Here's where my question arises)
I expected it to have the TPMS light come on solid saying that one of my tires is low... but instead it just went off. i figured maybe I need to drive it a bit to get the ECU to check the tire pressures and send out a warning. But after driving around to and from work for a day it hasn't turned on yet. Which got me thinking:
Our 4runners don't have a TPMS button to push to program the tire pressure like other toyota/lexus models. Perhaps when we program new sensors the ECU looks at the pressure they are at and stores that the pressure they should be and when the pressure drops to some number of PSI below that pressure, it then turns on to signal a low tire. Rather than having a pressure hard coded into the ECU that if the sensors drop below it turns on. Is that how the TPMS works?
Since I programmed my 4runner through the OBD2 with the spare sensor at regular air pressure that would explain why the light just went off. It thinks that 0PSI is what the tire is supposed to be at.
I plan to experiment this weekend with reprogramming the ecu with the spare sensor in some sort of pressure vessel and then letting the air out to see if it then triggers the low pressure indicator. But I was curious if anyone else has experienced this? I haven't seen any other threads going into detail just general TPMS questions.
If this is the case then this is a super simple way for people to get their TPMS light to go out without having to do the wiring mod. You simply take the 5 sensors from your OEM wheels reprogram the ECU to them at atmospheric pressure and throw them in the glove box, under a seat anyplace in the car and you don't have to worry about having them on aftermarket wheels.
On memorial day I was taking a road trip and about half way into the 3 hour trip my TPMS light started blinking in my 05 4runner. I knew that it meant a sensor has gone bad but I stopped at the next exit just to double check my tire pressures and do a quick online search to confirm. I continued on my way.
When I got back from the trip I took it to Les schwab to figure out which sensor went bad. They pulled it in and sent em to wait inside. about 15 minutes later the tech came in and claimed that he couldn't get a reading from any of the tires and all the sensors failed and would cost a little over 400$ to replace them all. I immediately left because I knew there was absolutely no way that all 5 batteries in each sensor would fail within 48 hours of each other.
Since I have been planning to get new wheels I figured now would be a good time. So I ordered 5 denso 5500101 sensors from rock auto for much cheaper than les schwab wanted. After some research I ordered a ATEQ Quickset to program the new sensors.
Well I still don't have my new wheels yet but I have the sensors and the quickset andd the blinking light on my dash was bothering me. I figured I'd rather have it on solid saying a tire pressure was low rather than blinking. I took the quickset and pulled the codes from the OBD2 port. They were as follows:
FL:095C4090
FR:09A09090
RR:04AD0090
RL:04ACF090
SPARE:01983090
Immediatly the spare stood out to me as being different than the other 4. I was pretty sure when I changed tires previously I had also had the TPMS replaced. which would mean that the 4 on were newer than the spare and the spare was likely my culprit. So using the Quickset tool I reprogrammed it to look for the same 4 sensors and one of the new sensors that I would just keep in glove box until my new wheels arrived.
(Here's where my question arises)
I expected it to have the TPMS light come on solid saying that one of my tires is low... but instead it just went off. i figured maybe I need to drive it a bit to get the ECU to check the tire pressures and send out a warning. But after driving around to and from work for a day it hasn't turned on yet. Which got me thinking:
Our 4runners don't have a TPMS button to push to program the tire pressure like other toyota/lexus models. Perhaps when we program new sensors the ECU looks at the pressure they are at and stores that the pressure they should be and when the pressure drops to some number of PSI below that pressure, it then turns on to signal a low tire. Rather than having a pressure hard coded into the ECU that if the sensors drop below it turns on. Is that how the TPMS works?
Since I programmed my 4runner through the OBD2 with the spare sensor at regular air pressure that would explain why the light just went off. It thinks that 0PSI is what the tire is supposed to be at.
I plan to experiment this weekend with reprogramming the ecu with the spare sensor in some sort of pressure vessel and then letting the air out to see if it then triggers the low pressure indicator. But I was curious if anyone else has experienced this? I haven't seen any other threads going into detail just general TPMS questions.
If this is the case then this is a super simple way for people to get their TPMS light to go out without having to do the wiring mod. You simply take the 5 sensors from your OEM wheels reprogram the ECU to them at atmospheric pressure and throw them in the glove box, under a seat anyplace in the car and you don't have to worry about having them on aftermarket wheels.
