mjclsi

Guys...I am lost. About four days ago my TPMS warning light started blinking. Same tires and sensors have been on there for quite some time. The service book says to take it to the dealer, but I instead stopped by Discount Tire (where I purchased the tires) to see if they could look and figure out which sensor was acting up.

When he ran his sensor, none of my four sensors showed up as broadcasting at all! Now I know that all four of my sensors did not just randomly go out at the same time.

Any thoughts on what might cause this?

RCsGX

Bad TPMS ECU and or bad receiver.

See attached PDFs.

lesz

On my 2005 GX, at the start of every winter and when we have the first days with temperatures in the 10-15 degree range, my tire pressure warning light will come on even though all of the tires, including the spare, are filled with the proper amount of air. Using the re-set button inside the glove compartment gets the warning light turned off within a few minutes, and the warning light stays off for the rest of the winter. If I remember correctly, what I've done is to switch the button to the setting for a 2nd set of wheels and, then, switched it back to the setting for the first set of wheels.

RCsGX

Mann777 showed a picture from a manual that showed the a/b in the glovebox but it's in the place of where the CD changer would be? I would think that all GXs came w/ CD changers but maybe not...do you have a CD changer in your '05?






I have an '05 too and in my manual it shows the a/b switch below the steering wheel, which is exactly where it's at.

lesz

You are right, it is below the steering wheel. I was confused and mistakenly thought it was in the glove compartment because that was where a Lexus service adviser mistakenly told me to look for it the first time that I was looking for it. In any case, switching back and forth from the A position to the B position and, then, back to the A position has, for me, re-set the system and turned off the warning light when it has come on when it should not have come on

I should also add that, when I've used this method to get the warning light to go out, it has not gone out instantly, but, after a few miles of driving after using the switch, it has gone out.

RCsGX

^ Gotcha....

lexo98

iTrader: (2)

If none of your sensors are responding to his scan tool it's not a problem with the ECU. In my experience the scan tool is not as strong as the vehicle ECU when it comes to receiving the sensors signal. Chances are maybe only one is triggering the light, but most likely all are low enough to not read on discount tires scanner. The recommendation would be to replace all 4. If your vehicle is an 05 like when you joined the forum or have 80k miles it's probably time.

RCsGX

The OP said his TPMS light is blinking. A blinking light is a sign of some part malfunctioning within the system whether it's one or more of the tire sensors, ECU or receiver. Before I started spending money on replacing sensors I'd take it to Lexus first. No need in wasting money on 4 new sensors if that's not the cause of the problem in the first place.

mrblister

The tpms have lithium batteries in them that can last to up to 7,8, & in some cases 9 years. If one is triggering then most likely the batteries are near there end of life. They are really not replaceable but some people have attempted to do so. If you ever have had to change a cmos battery in a computer which are mostly lithuim you have to spot tack the flat wire contact to the battery. You cant solder it because the heat can and will cause the battery to explode. I have access to spot welder which charges a small electric charge to instantly fuse the wire to the battery. I have done this before . I have learned over time its best to get all new sensors and make sure of the date code and make sure they are a set of 5 different colors to include the spare. On my sc430 I only have to change 4 no spare.

RCsGX

I agree but if the OP doesn't know 100% that's it's a / the sensor(s) causing the blinking light there's no need to start spending money just yet. His best bet is to do what his manual says and take it to the dealer so he can find out the exact cause of the blinking light.

The sensors themselves are potted and the only way to remove potting material is w/ heat so unfortunately replacing the batteries aren't an option. Too bad because it would make dealing w/ tire sensors a lot easier if it was a simple battery swap.

lexo98

iTrader: (2)

After someone has tried to reset the system numerous times it goes into a lock out mode. Still sounds like it's the actual sensors. I don't disagree taking it to the dealer but depending on if they take mercy on you it might cost a lot more money.

Siven

I am cutting and grounding every wire going into the Module until I find the one that sends the signal to the dash. If I want to run with a low pressure for extra traction I sure don't need a yellow light in my face. Bad design.

RCsGX

I can see needing to air down in certain situations but the light will go off once you air back up. As per Lexus, the GX is supposed to be at 32PSI. I don't see why anyone would want or need to run a lower pressure full time? Most run tires at 35-40PSI.

If you do want to run them lower you can always have the main pressure reset. Example, lets say you want to run your tires at 25PSI all the time. You can have the main pressure set at 25PSI so the light won't come on until you drop well below 25PSI.

The system works fine and works how it's been designed to work, so I don't see how it's a bad design? I've had them on almost every vehicle and I've never had any problem w/ the system.

mjclsi

Hey guys...thanks for all of the help. We have been travelling (just dealt with the blinking light which has driven me CRAZY!) I am going to attempt the master reset and see what happens. Just like one person earlier...none of this happened until our first bought of truly freezing weather (which is a rarity in Texas.) Thanks again.

mjclsi

Hey guys...quick update. I looked at the switch (never realized it was there) and it was set to "2nd" instead of "Main" so I switched it back to "Main". Light went off. I'm wondering if me or my wife accidentally hit it somehow. I would have never found it without y'all, so thanks again! I really appreciate it.