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Discussion Starter #1
Hi guys,

I want to mute the TPMS light when I have winters on. I've seen various write ups for the Yaris, Rav4, etc. I have the service manual but for the life of me can't find the wiring diagram for the TPMS ECU. Anyone have it? Or can tell me which part of the service manual to look in? Is it called something other than TPMS ECU?

Once I perform the mod I will write up and share with the forum.

Thanks.
 

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I looked in my repair manual too and can't seem to find anything at all. I looked everywhere. If it is in there it must be very little info. Seems there should be a receiver mounted somewhere and then likely some wiring to the ECU for the system. I'm curious about this now, so will be looking more. Maybe others have found these components and will chime in soon.
 

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Discussion Starter #3
I hope one of the CT experts in here knows something. I think a write up about a TPMS light bypass would be very beneficial to all of us and should be an easy mod.
 

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Discussion Starter #4
i think i found the problem. the manual that people have been passing around is for the european model which does not have a tpms system.

does anyone in here have the service manual for the US spec ct200h? if so, can they please look for the wiring diagram for the combination meter and see if there is a tpms light in that diagram?
 

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Wow.. I think you are right. I never noticed anything that let me believe the manual I had was other than for US until now. I looked under "new car features", "general", "major technical specs" and it only mentions "models for Europe" and "models for GCC countries" (Qatar, Saudi, etc).

Nice to learn this, but would love to find the USA spec manual.. Thanks!
 

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I hope one of the CT experts in here knows something. I think a write up about a TPMS light bypass would be very beneficial to all of us and should be an easy mod.
When I first got the CT I subscribed for 24 hours to a Lexus online repair info website. I think it is one the Lexus service guys can use. Can't find the link now, but.. during that 24 hours I saved a good number of files including wiring diagrams. I just checked and there it is. I have the TPMS wiring diagram. PM me your email address and I will send it to you. R:)
 

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So it looks like it is likely the Green wire coming out of the ECU going to the Combination Meter that supplies power for indication of the tire pressure warning light. (or it could just be providing signals to the CM???)Could you break that wire and maybe extend those wires over to a new push button switch using one of the spare spots in the 5 button bank left of the steering wheel? I have 4 spare spots there, but maybe you don't.
 

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Discussion Starter #8
PM sent for that wiring diagram!

I need to see where the ECU is located. If it's near the glove box I will just mount a small switch there so it can't be seen. Just open the glove box or something like that to turn on/off. That way everything appears stock.
 

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PM sent for that wiring diagram!

I need to see where the ECU is located. If it's near the glove box I will just mount a small switch there so it can't be seen. Just open the glove box or something like that to turn on/off. That way everything appears stock.
On the way...

I found a parts location diagram and system diagram in addition to the wiring diagram. Hard for me to understand if that green wire sends a communication signal or power. Good luck. Look forward to seeing what you can do.
 

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Discussion Starter #11
Success!!!!

I was able to add a switch so I can toggle between the default wiring and one where the light is disabled!!! Will post a write up with pics and wiring diagrams tonight!!!
 

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Success!!!!

I was able to add a switch so I can toggle between the default wiring and one where the light is disabled!!! Will post a write up with pics and wiring diagrams tonight!!!
omg! that is going to be one of the best how-to writeups for this car!

thank you so much for taking the time to figure this out!
 

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Discussion Starter #13 (Edited)
I am separating the write up into parts:
1) Concept - This is all you need for the basics
2) Actual install with pics
3) Description with pics of how to remove air bag and glove box.

Part 3 may not be necesssary. During the install I discovered you can remove the lower cover under the air bag and may be able to access the TPMS ECU from there. I can't confirm this as I put everything back together without verifying this but it does look like it is possible. On the Prius the ECU is up high behind the glove box. On the CT it's down low near your feet.
 

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Discussion Starter #14
TPMS Toggle Switch - Conceptual

Concept

The basic idea is to supply a constant +V signal to the TPMS light signal. Whenever this signal drops (below 7V I’m guessing) the TPMS light will go on. Unplugging the TPMS ECU will not disable the light because this causes a 0V signal to go to the TPMS light. See diagram below.

The idea is pretty simple. When the toggle is in the ON position you end up with the default wiring. +12V goes to 7 to power the ECU.

When the toggle is in the OFF position you cut power to the ECU and the +12V goes to the TPMS light. In this position the ECU is not detecting any signal. There is no harm to anything. Your original TPMS sensor codes are still there. When you power the ECU again it will detect your old sensors when you put your summers back on.


TPMS Location




System Diagram






Wiring Diagram - TPMS





Wiring Harness Pinouts

This is the view from the back of the harness. That is you are looking at this from where the wires run into the harness, not the end that goes into the ECU. On my CT200h the harness will label the 7 and 12 pin so you can’t screw up too bad.
For quick reference:
5 – Goes to combination meter for TPMS light
7 – Power +12V
9 – Ground




Appendix A – Background from Prius

The Prius solution is very similar to the one we need for the CT200h. You want to send a +12 signal to the 5 pin in the TPMS ECU harness. This turns the light off. The wiring pins are the same between the Prius and the CT200h but the location of the ECU is different so use this picture as background but NOT reference.

 

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Discussion Starter #15
oh and I need to send out a BIG thanks to kalo925 for the wiring diagrams. my freebie lexus support manual is for euro cars and did not include the location of the tpms ecu. could not have done this without kalo925
 

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Discussion Starter #16 (Edited)
Switch Connections

I used 18-22AWG scotloks to make the connections.

Cut the beige wire. That’s the +12V used to power the ECU. The 2 cut ends of the beige wire go to separate connections on the toggle switch.

The green wire is the signal going to the combination meter to turn the TPMS light on/off. I left that uncut. I connected that with the scothlok to the 3[SUP]rd[/SUP] connector on the toggle switch.



Harness

The beige wire is the +12V power. The green is the signal to the combination meter.

The 7 and 12 pins are marked on the back of the harness.



ECU Location

The ECU is located at the bottom of the control box. This is different from the Prius which has the ECU at the top of the control box. Because I was looking at the Prius diagram I thought I had to remove the glove box to access the ECU but in fact you do not have to. It is possible to access the ECU but just removing the bottom cover under the knee air bag.



The arrow shows the location of the ECU.


The arrow shows the wire bundle going into the ECU.


The ECU is marked with “ABS”. This was really confusing. It didn’t look like the ECU.

Toggle Switch




The toggle switch is accessible from the foot well. I ended up securing the wire to the carpet with velcro. The switch is not visible but easily accessible.

 

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oh and I need to send out a BIG thanks to kalo925 for the wiring diagrams. my freebie lexus support manual is for euro cars and did not include the location of the tpms ecu. could not have done this without kalo925
No problemo. That light on would annoy me too, but since I'm in Sunny California, no 2nd set of wheels needed. Great post and info.
 

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Thanks usando. Great guide. I installed the switch today and it worked great. A few notes:

1. I used a 3-terminal Single-Pole Double-Throw (SPDT) ON-ON switch for those who aren't familiar with the many switches which are available.
2. I can confirm that removing the lower panel below the airbag is enough to access the harness to the TPMS ECU. The panel is just attached by clips.
3. I used a scotchlok on the green wire and it was a b*tch to get on. That may have been because the wires I have going to the switch are 18 gauge and the car's harness wires are 22 gauge.
4. The 12V wire is described as 'beige' by the OP. It looked brown to me.
5. After cutting the 12V wire, I used T-taps instead of scotchloks. There's not much wire length to work with after cutting and I found getting the T-taps on way easier than the scotchlok I used on the green wire. I would probably use a T-tap on the green wire if I were to do this again.
6. I ran the wires+switch up the left side of the passenger footwell up to the glovebox. There's a piece of removable plastic there. I took that piece out, drilled an appropriate sized hole for my switch and mounted it. Please see pictures below:

 

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Location of ECU in 2015 Lexus CT200h

hello, reading some amazing work on disabling the TPMS. I got the impression this was for a Prius, just wanted to confirm the location of the ECU would also be below the passenger side airbag in a Lexus CT200h?
 
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