DIY - Bypassing Tire Pressure Warning System (TPWS / TPMS)

[CTScott]

Yes.

[auxmike]

Originally Posted by CTScott

Yes.

OK then.
SO, this method does NOT require the the light to be off pre procedure OR that the wheels/sensors to be mounted on or near the car before starting, right? Even if you start out with the light on, it does'nt matter this way.
Is this all true?
Thanks!

[CTScott]

Originally Posted by auxmike

OK then.
SO, this method does NOT require the the light to be off pre procedure OR that the wheels/sensors to be mounted on or near the car before starting, right? Even if you start out with the light on, it does'nt matter this way.
Is this all true?
Thanks!

That is correct. This mod actually just disables the warning light, which is why the initial state before doing the mod does not matter.

The TPWS is completely independent of all other systems on the car. It actually uses legacy ISO-9141 comm, rather than CAN bus, so the ECM doesn't even have the ability to talk to it.

[hackenfort]

CTScott,

Just wanted to say THANK YOU!

This is the first thing I did when I bought my new Yaris a few months back.

Sure beats taking the inst cluster out and covering the led for the light!

so THANKS AGAIN!

Kevin

[zelig]

Originally Posted by CTScott

That is correct. This mod actually just disables the warning light, which is why the initial state before doing the mod does not matter.

The TPWS is completely independent of all other systems on the car. It actually uses legacy ISO-9141 comm, rather than CAN bus, so the ECM doesn't even have the ability to talk to it.

So the light is the only onboard indicator of TPMS state? Is there a service tool to interface with the TPMS and read/report status? I suppose I'm basically wondering if there's any advantage to tricking the system into seeing a "good" state vs just disabling the warning light.

Also, is there any identifier such as a part number on the TPWS ECU?

I'm really excited to try this!

[CTScott]

Originally Posted by zelig

So the light is the only onboard indicator of TPMS state? Is there a service tool to interface with the TPMS and read/report status? I suppose I'm basically wondering if there's any advantage to tricking the system into seeing a "good" state vs just disabling the warning light.

Also, is there any identifier such as a part number on the TPWS ECU?

I'm really excited to try this!

The TPMS is completely independent of the ECM, but the Toyota Techstream tool can communicate with it via the ODB port. The TPMS is the only system on the Yaris that does not communicate over CAN BUS, but rather just communicates via the older ISO-9141 spec. So, there really isn't any advantage to tricking the system instead.