Tire Monitor System - Diagnostic Tips

PRODUCT GENERAL INFORMATION
PG004-06

Title:
DIRECT-TYPE TIRE PRESSURE
WARNING SYSTEM DIAGNOSTIC TIPS

Models:
'04 - '07 Applicable Scion

November 28, 2006

Introduction

The Tire Pressure Warning System (TPWS) monitors the difference in tire pressure in all four or five tires (if the vehicle is equipped with a full-size spare tire) through radio wave signals from a tire pressure valve/sensor mounted in each wheel.

This bulletin provides an overview and diagnostic information for the direct-type TPWS.

Applicable Vehicles

^ 2007 model year Scion tC vehicles.





Required SSTs





Warranty Information

Summary of TPWS/Component Operation

^ Tire Pressure Warning System Antenna/Receiver:

The antenna/receiver receives each tire pressure, tire temperature, and the unique tire pressure warning valve/sensor ID numbers through radio wave signals from the tire pressure warning valve/sensors and then transmits the information to the TPWS ECU.

^ Tire Pressure Warning System ECU:

The ECU takes each tire pressure, tire temperature, and unique tire pressure warning valve/sensor ID information from the antenna/receiver and compares it to the specified value, which was registered during PDS. If the information received does NOT match the specified value registered in the ECU, it will transmit a signal to illuminate the Tire Pressure Warning System Indicator Light located on the combination meter. If the ECU is replaced, it is necessary to manually enter the tire pressure valve/sensor ID numbers using the Diagnostic Tester.

^ Tire Pressure Warning System Indicator Light:





The Tire Pressure Warning System Indicator Light on the combination meter is illuminated or flashes continuously when the ECU senses that the tire pressure, tire temperature, and/or unique ID number does NOT match the specified value registered in the ECU.





Conditions for the Tire Pressure Warning System Indicator Light "ON" or "Flashing" are listed in the table shown.

^ Initialization/"SET" Switch:

When initializing the TPWS, the present tire pressure is set as the standard pressure (for example: 32 psi). The TPWS determines a decrease in air pressure by comparing the standard pressure to the tire inflation pressure received from the tire pressure warning valve/sensor. Reasons for initializing the system include:

^ When rotating tires that have different tire pressures in the front and rear.

^ When changing or adjusting the tire pressure.

^ When changing tire size or when tires are replaced.





The vehicles listed in the table are equipped with an Initialization/"SET" switch:

^ "MAIN/2nd" Switch (Land Cruiser vehicles ONLY):

Land Cruiser is the ONLY Toyota vehicle with the "MAIN/2nd" switch. This allows the owner to have two different sets of tires and wheels, with two different sets of tire pressure warning valve/sensor ID numbers. For example, the second set would be used for snow tires. Therefore, register both the main and the second set of tire pressure warning valve/sensor ID numbers in the TPWS ECU using the Diagnostic Tester. Depending on what set of tire pressure warning valve/sensor ID numbers are being registered, the "MAIN/2nd" switch must be set in the correct position (i.e., "MAIN" for regular use tires and "2nd" for snow use tires).

^ "MAIN/2nd" switch in the UP position The TPWS ECU is programmed to read the main set of tire pressure warning valve/sensor ID numbers.





^ "MAIN/2nd" switch in the DOWN position The TPWS ECU is programmed to read the second set of tire pressure warning valve/sensor ID numbers.

Diagnostic Tester Setup





When diagnosing the TPWS with the Diagnostic Tester, it must be set up to read the tire pressures in "psi - gauge" (psi - g). Follow the screens below from the Diagnostic Tester to convert the tire pressures to psi - g.








System Concerns & Repair Methods

Registration Procedure

Registration of tire pressure warning valve/sensor ID numbers:

1. Jump TC and CG at DLC3 with the key ON and eEngine OFF for 30 seconds.





2. Register the 7-digit IDs:

3. Confirm the actual tire pressure to the Diagnostic Tester Data List and set according to the tire inflation pressure indicated on the vehicle loading specification label.

4. Confirm that the Tire Pressure Warning System Indicator Light is OFF.

5. Push and hold the Initialization/"SET" switch (if equipped) until the Low TPWS Light blinks 3 times and then release the switch. Keep the ignition key ON for 5 minutes for the system to initialize.

The registration is complete.











Diagnostic Flow Chart