Toyota Yaris Forums - Ultimate Yaris Enthusiast Site
 

 


 
Go Back   Toyota Yaris Forums - Ultimate Yaris Enthusiast Site > Technical Forums > DIY / Maintenance / Service
  The Tire Rack

Reply
 
Thread Tools Display Modes
Old 11-24-2008, 12:32 PM   #1
CTScott
ULTIMATE
 
CTScott's Avatar
 
Drives: 09 5dr LB, 2x 08 3dr LB
Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
DIY - Bypassing Tire Pressure Warning System (TPWS / TPMS)

Note: Please jump to page 3, post #45. The first pass of a solution on pages 1-3 ended up not working.

For the simple method, please jump to post 115. This method does not require resistors.

http://www.yarisworld.com/forums/sho...&postcount=115


Following is a DIY to disable the system, without causing the TPWS light or MIL (malfunction indicator light {or check engine light, as some like to call it}) to light.

A while back there was a thread about the issues with either using rims which are not compatible with the tire pressure sensors or running two sets of rims. The Yaris TPWS can only be programmed to respond to one set of four sensors. To switch to a second set, you would have to bring your car to the dealer to have the TPWS reprogrammed for the second set (This is typically about a $90 charge).

I did a bit of reverse engineering on the TPWS and believed that I found a soultion. Linny recently tried this solution and verified that after more than 100 miles of driving there were no issues.


Procedure :
(WARNING: Modifying anything on the Yaris is done at your own risk!!!)


The TPMS ECU is located behind the lower passenger glove box:




The TPWS system will only report an issue with not hearing from the sensors if for 15 minutes it doesn't hear from a sensor while the vehicle speed is 5 MPH or greater and the Engine speed is 1000 RPM or more.

To keep the system from reporting an error, do the following:

1. Start without an error: If you start with the system in the error free state (by starting the vehicle and having the 4 tires with the sensors next to the vehicle (or mounted on it) and ensure that the TPWS light is not lit or flashing.

2. Shut the engine off.

3. Pull out the lower passenger glove box and locate the TPWS ECU (to the right, just above the fan assembly):



3. Clip and cap both ends of the VSS and ESS wires to the TPWS ECU. Leave a couple of inches on the connector side so that you can resplice if you wish to re-enable the system. The connector is shown below. The VSS wire is the Violet one and the ESS wire is the red one, two pins after the violet one. Also, if you wish to switch between a set of rims with sensors and a set without, you can add a DPST (dual pole, single throw) switch to disconnect / reconnect both wires as desired to disable/enable the TPWS.



For adding the switch the following is a good choice:



http://search.digikey.com/scripts/Dk...?name=CH867-ND

To wire the switch, connect the cut wires to the sets of terminals on either side of the switch as follows:

Red - - Red
Vio - - Vio


Someone posted a DIY of disabling the feed to the light (the brown wire on the connector above, if you were wondering). The problem with just clipping this wire is that the DTCs will still be logged and may result in your Malfunction Indicator Light coming on.

Last edited by CTScott; 09-23-2009 at 01:57 PM. Reason: Point users to the working solution.
CTScott is offline   Reply With Quote
Old 11-24-2008, 12:51 PM   #2
Tamago
Start another Oil Thread!
 
Tamago's Avatar
 
Drives: ZZW30
Join Date: Dec 2006
Location: South FL
Posts: 4,890
Send a message via AIM to Tamago Send a message via Yahoo to Tamago
very nice :)
Tamago is offline   Reply With Quote
Old 11-24-2008, 01:03 PM   #3
kou
 
Drives: 08 lb
Join Date: Aug 2007
Location: nj
Posts: 935
i will be doing this in the spring.thank you.
kou is offline   Reply With Quote
Old 11-25-2008, 12:27 PM   #4
TheSilkySmooth
 
TheSilkySmooth's Avatar
 
Drives: 08 3DR 5M Bayou Blue; 09 Fos
Join Date: Oct 2008
Location: New Hampshire
Posts: 622
Super DIY write up. Thank you CTS for the effort! I am planning to put vinter tyres on My Daughter's Yaris and was concerned about setting a code as she is due for Emissions and saftey inspection this november. The SW seem like a good idea. CTS You dont have to shunt any of the cut wires to keep an open antenna out of the ECU?

Does anyone know if the 14" steel rims sold through Tire rack or Discount Tire Direct will clear the calipers? Her car has optional 15 inch rims. I wish to put a 165-70 snows on the front to get better force/unit area (µN/cm2) at the contact patch.

Thank you for helping,

- Papa
TheSilkySmooth is offline   Reply With Quote
Old 11-25-2008, 12:34 PM   #5
Tamago
Start another Oil Thread!
 
Tamago's Avatar
 
Drives: ZZW30
Join Date: Dec 2006
Location: South FL
Posts: 4,890
Send a message via AIM to Tamago Send a message via Yahoo to Tamago
Quote:
Originally Posted by TheSilkySmooth View Post
Super DIY write up. Thank you CTS for the effort! I am planning to put vinter tyres on My Daughter's Yaris and was concerned about setting a code as she is due for Emissions and saftey inspection this november. The SW seem like a good idea. CTS You dont have to shunt any of the cut wires to keep an open antenna out of the ECU?

Does anyone know if the 14" steel rims sold through Tire rack or Discount Tire Direct will clear the calipers? Her car has optional 15 inch rims. I wish to put a 165-70 snows on the front to get better force/unit area (µN/cm2) at the contact patch.

Thank you for helping,

- Papa
14's should clear fine, stock brakes aren't huge.. +39 offset should work as well
Tamago is offline   Reply With Quote
Old 11-25-2008, 12:36 PM   #6
CTScott
ULTIMATE
 
CTScott's Avatar
 
Drives: 09 5dr LB, 2x 08 3dr LB
Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
Quote:
Originally Posted by TheSilkySmooth View Post
Super DIY write up. Thank you CTS for the effort! I am planning to put vinter tyres on My Daughter's Yaris and was concerned about setting a code as she is due for Emissions and saftey inspection this november. The SW seem like a good idea. CTS You dont have to shunt any of the cut wires to keep an open antenna out of the ECU?

Does anyone know if the 14" steel rims sold through Tire rack or Discount Tire Direct will clear the calipers? Her car has optional 15 inch rims. I wish to put a 165-70 snows on the front to get better force/unit area (µN/cm2) at the contact patch.

Thank you for helping,

- Papa

No shunting is required. The two wires we are disconnecting are both 12 V analog signals which the ECU is pulling through A to D converters. We shouldn't be able to pick up enough noise to cause a false signal detection.
CTScott is offline   Reply With Quote
Old 11-25-2008, 12:39 PM   #7
Tamago
Start another Oil Thread!
 
Tamago's Avatar
 
Drives: ZZW30
Join Date: Dec 2006
Location: South FL
Posts: 4,890
Send a message via AIM to Tamago Send a message via Yahoo to Tamago
Quote:
Originally Posted by CTScott View Post
No shunting is required. The two wires we are disconnecting are both 12 V analog signals which the ECU is pulling through A to D converters. We shouldn't be able to pick up enough noise to cause a false signal detection.
i thought speed and tach signals were both pulse signals.... ?
Tamago is offline   Reply With Quote
Old 11-25-2008, 12:44 PM   #8
CTScott
ULTIMATE
 
CTScott's Avatar
 
Drives: 09 5dr LB, 2x 08 3dr LB
Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
Quote:
Originally Posted by Tamago View Post
i thought speed and tach signals were both pulse signals.... ?
They are frequency modulated pulses. The TPMS microcontroller pulls them in through an analog input.
CTScott is offline   Reply With Quote
Old 11-25-2008, 12:53 PM   #9
Tamago
Start another Oil Thread!
 
Tamago's Avatar
 
Drives: ZZW30
Join Date: Dec 2006
Location: South FL
Posts: 4,890
Send a message via AIM to Tamago Send a message via Yahoo to Tamago
Quote:
Originally Posted by CTScott View Post
They are frequency modulated pulses. The TPMS microcontroller pulls them in through an analog input.
ah cool so where they enter the ENGINE ecu they're pulse signals, then they go out to the cluster as pulses (correct me if i'm wrong, i recollect setting up a Defi VSD heads up display, and grabbed pulse signals for tach/speed) and the ECU also sends analog outputs to the TPMS?

do you have a wiring diagram of the ECU?
Tamago is offline   Reply With Quote
Old 11-25-2008, 01:14 PM   #10
CTScott
ULTIMATE
 
CTScott's Avatar
 
Drives: 09 5dr LB, 2x 08 3dr LB
Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
Quote:
Originally Posted by Tamago View Post
ah cool so where they enter the ENGINE ecu they're pulse signals, then they go out to the cluster as pulses (correct me if i'm wrong, i recollect setting up a Defi VSD heads up display, and grabbed pulse signals for tach/speed) and the ECU also sends analog outputs to the TPMS?

do you have a wiring diagram of the ECU?
The ECU sends the same pulsed signal to the cluster and the TPWS. The Combo Meter has a microcontroller, which reads the tach and VSS inputs directly, as well as a CAN bus interface to get the odo data and MIL input from the ECU. All of the "data" signals are 12 V, so the microcontrollers have to level shift them to use them (via optoisolator, A-D, etc.).

The Defi's micro would have to do the same thing. By the way, was the Defi VSD worth the money?

For the wiring diagrams, I just have the 09 service manual.
CTScott is offline   Reply With Quote
Old 11-25-2008, 01:20 PM   #11
Tamago
Start another Oil Thread!
 
Tamago's Avatar
 
Drives: ZZW30
Join Date: Dec 2006
Location: South FL
Posts: 4,890
Send a message via AIM to Tamago Send a message via Yahoo to Tamago
Quote:
Originally Posted by CTScott View Post
The ECU sends the same pulsed signal to the cluster and the TPWS. The Combo Meter has a microcontroller, which reads the tach and VSS inputs directly, as well as a CAN bus interface to get the odo data and MIL input from the ECU. All of the "data" signals are 12 V, so the microcontrollers have to level shift them to use them (via optoisolator, A-D, etc.).

The Defi's micro would have to do the same thing. By the way, was the Defi VSD worth the money?

For the wiring diagrams, I just have the 09 service manual.
i've installed 3 sets.. one on my xA the base VSD.. it was essential to life for me until it was vandalized :( it would record max speed/RPM which worked well for primitive datalogging at autocross..

the second one was the VSD that would hook up to the LINK system.. this one went in the yaris. speed/tach on the windshield is awesome..

i now have a VSD-X for my xA.. it has its own screen. i had it installed for a bit then removed it. it's a nice piece but a little OTT for this build. i believe DEFI has discontinued all their HUD's..
Tamago is offline   Reply With Quote
Old 11-25-2008, 09:01 PM   #12
Chupacabra
Banned
 
Drives: 2009 Yaris liftback
Join Date: Nov 2008
Location: CT
Posts: 350
Scott,
Insanely awesome thread! Thank you!!!....
Chupacabra is offline   Reply With Quote
Old 11-25-2008, 09:20 PM   #13
blacksandiegovitz
Your mom goes to college
 
blacksandiegovitz's Avatar
 
Drives: 08 Vitz
Join Date: Oct 2008
Location: Just chillin' out brah !
Posts: 1,434
Man soooo killer. Installed trd/racing hart 18" and didn't have the sensors installed on them , Im so over the "warning" light on the dash . I'll be doing this this weekend .
blacksandiegovitz is offline   Reply With Quote
Old 11-26-2008, 04:02 PM   #14
linny
 
Drives: '08 liftback mt
Join Date: Nov 2008
Location: Mn
Posts: 39
Thumbs up

The hardest part about this procedure was pulling the glove box out! Thanks CTSCOTT! I tried to get the service guy at our dealer to tell me how to disable the system and he wouldn't budge. He would just offer that what most people do is simply 'deal' with the light since most do not have the want or resources to drop $90 each time they want to switch rims/tires.
linny is offline   Reply With Quote
Old 11-26-2008, 04:24 PM   #15
mikenacarato
SIPNDEW
 
mikenacarato's Avatar
 
Drives: 15 STI
Join Date: Oct 2008
Location: Brentwood, TN
Posts: 2,281
Send a message via AIM to mikenacarato
very nice! i was just about to ask if there was a way to bypass it and then i saw this.
mikenacarato is offline   Reply With Quote
Old 11-26-2008, 06:11 PM   #16
Ratboy
 
Drives: Sedan
Join Date: Oct 2008
Location: Baltimore
Posts: 6
okay...you guys lost me. Do you need to cut the wires or can you just leave it unplugged? Or are you just cutting the two wires?
Ratboy is offline   Reply With Quote
Old 11-26-2008, 07:42 PM   #17
linny
 
Drives: '08 liftback mt
Join Date: Nov 2008
Location: Mn
Posts: 39
I cut the two wires as specified in the pictures provided by CTSCOTT. After cutting the wires I wrapped each of the ends from the two wires in electrical tape. I then plugged the connector back into the ECU unit and that is it!!
linny is offline   Reply With Quote
Old 11-26-2008, 09:50 PM   #18
Yarice
 
Yarice's Avatar
 
Drives: 2008 LB Meteoric Metallic
Join Date: Oct 2008
Location: Victorville, CA
Posts: 200
Does this project also work for an 2008 3dr LB?
Yarice is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tire pressure sensors Tink1 Wheels, Tires and Suspension Forum sponsored by The Tire Rack 11 10-21-2008 05:53 PM
Intake Systems Decision Maker.. Blenjar Performance Modifications 25 09-15-2007 10:07 PM
The Tire inflation debate... Tankota General Yaris / Vitz Discussion 20 06-01-2006 07:09 PM


All times are GMT -4. The time now is 08:15 AM.




YarisWorld
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.