Flapjack1

I had the dealer deliver a spare wheel and tire that matched the 19" rims that were on the car rather than the 18" that they stuck in there. Once I put the new spare in the trunk and drove for a few miles the TPMS went off. Is this a dealer visit?
I am using the reset button under the dash but it will not reset.

My guess is that the sensor in the new wheel will need to be registered with car.....dealer visitor. What a PITA!

Or am I way off base here?

jmcraney

If the sensor in your new spare is not registered in your car's TPMS then the alarm condition and the new spare are not related.

The button under the dash, the one you refer to as a "reset" switch is not a reset switch and will not cancel alarms. That button is a benchmark "set" switch.

Your alarm condition is likely related to an under-inflated tire or tires, or your system is mal-benchmarked, or a combination of both.

The first thing you would need to do is clear the alarm condition. Usually just inflating the tires to 33 PSI will do that. So, with the ignition off, inflate your tires to 33 PSI and then turn the ignition on, you don't need to start the engine, and wait for the tire pressures to be displayed in the display on the car's dash. The display will initially say "CHECKING" at each tire position and when it receives an input from the tire sensors it will display the tire pressure. It takes a minute or two to get all five tires.

If you are able to get a pressure (or a "CHECKING" from any missing sensors) from all tires without an alarm condition then you can benchmark the TPMS by holding the SET switch depressed until the display flashes three times (you have to do this with the ignition on but the engine does not have to be running and for safety it is best to do it without the engine running). If your old spare, the one with the sensor, is within range of your car's system then it must be included in this process.

I don't think the benchmark switch will work in the presence of an alarm condition so if you still have an alarm then it is likely caused by mal-benchmaking and you will have to do a stepwise benchmark. I will not get into that unless it is necessary.

Once you get your tires properly benchmarked then you need to avoid operating that switch.

I am not sure what to tell you about your spare without more information.

Flapjack1

Tires are properly inflated (took it to Discount tire last night but they could not reset it). The spare must not be matched/calibrated thus tripping the alarm. I hate having to go to the dealer for something as stupid as this, plus I will likely have to pay $60 for it.

jmcraney

A none reporting sensor will not cause an alarm.

So, the first thing you need to do is get the spares out of the picture by separating them from the car by either taking the spares to a remote location or moving the car several blocks from the spares. Then turn the ignition off and restart the car. If you get an alarm then it is coming from one of the four tires on the car. The next thing you would need to do is try to clear the alarm by over-inflating the tires, probably 42 PSI will do it. Turn the car off and restart it. If the alarm is cleared then you would need to operate the Benchmark Switch as I told you before. Then adjust the pressure in all tire to 35 PSI, turn the ignition off, restart the car and if there is no alarm do the Benchmark set again. Then adjust the tires to 33 PSI and repeat the process.

If that doesn't work for you then it is possible that someone benchmarked with one of the tires while it was grossly overinflated, for example 60 PSI which would set the warning threshold at 45 PSI. It becomes dangerous to try to overcome an extreme situation.

The next option is to disconnect the car battery for a few minutes. I believe that will set the benchmarks to 33 PSI (warning thresholds to 25 PSI). Disconnecting the battery will cause loss of your radio presets.

Tell us what happens when you do this.

edarte

When I switched from my summer wheels to winter I first get the checking message and then after driving 10-15 miles I get the chime and warning. When I take car back to garage the system picks up signal from summer wheels in my garage and goes back to normal. Happens every day.

Now if the dealer took the original spare away would not the system be triggered in the same way when it can't find it? I think the new spare also needs to be registered.

slam_w2k

I did the same with a new spare tire. You have to take both tires to either the dealer or a tire store to take the old tire out from your car computer then add the new tire in. No other way to get around it!

jmcraney

I do understand that there is an alert chime and message warning of TPMS problems if any sensor fails to report for about 30 minutes. However the Low Pressure Warning alarms come from sensors reporting a pressure below the alarm threshold and that is almost instantaneous. It is very easy to recognize a bad or missing sensor by observing the tire pressure reports on the multifunction display. Sensors that fail to report will continue to display "CHECKING" until the thirty minute timeout expires and then you will get an alert chime and message warning of TPMS problems. The low pressure alarms are displayed by showing all five pressures on the Multifunction Display with those that are below the alarm threshold highlighted.

Flapjack1

It was the new spare as I suspected. The sensor in that new wheel needed to be registed to the car by the dealer. I'm glad that warning bell/light is finally gone

jmcraney

You don't have to go to a Lexus dealer and spend $60 to get this done. We had a discussion about this recently and you might find some useful information here: https://www.clublexus.com/forums/ls4...-question.html

MikeE12345

Flapjack1,

Why don't you respond to jmcraney's detailed advice/comments by letting him know what type of warning you got; i.e. a "Checking" timeout or immediate pressure warning. This would clarify what was going on and that would be helpful to all of us as well.

Flapjack1

I am not sure what type of warning was going on but as soon as you start the car the two yellow lights would come on the dash and stay on....the low tire light and the yellow warning light in the tach. Dealer performed this service for free and said it happens all the time. During this TPMS warning light situation I had no access to see my individual tire pressures. Hope this helps clarify a bit. Coming off a bimmer to a Lex is a bit of a change when it comes to understanding the warning displays....I have yet to thoroughly read the 650 page owners manual but plan to skim through it soon.

Flapjack1

I appreciate the insight from that thread but my local discount tire was no help about adding the sensor to the car's system, they did not have a clue. They could crawl all around the TPMS on the BMW 750 but the LS seemed to leave them dumbfounded. I saw that in that thread you mentioned expensive electronic tools for a DIY, that might occur once a year....I'll pass on that. The dealer said bring it back anytime this occurs again and they will fix for free.....Sewell in Dallas.....great people.