Tire Pressure Monitor - Initialization Procedure
PRODUCT GENERAL INFORMATIONPG005-04
REVISED
October 7, 2004
Title:
TIRE PRESSURE WARNING SYSTEM INFORMATION AND RE-INITIALIZATION
Models:
'04 - '05 Highlander, RAV4, Sienna, & Solara, '05 Scion tC
TSB REVISION NOTICE:
^ July 25 2005: 2005 model year Scion tC has been added to Applicable Vehicles.
A note has been added to the "Initialization Conditions" section. The "Initialization Procedure" and "Verify Initialization" sections have been removed. The "Reset/Re-initialization Procedures" and "System Limitations" sections have been added. PLEASE READ ENTIRE TSB.
Previous versions of this TSB should be discarded.
Introduction
This service bulletin provides the proper procedures for normal maintenance re-initialization of the indirect Tire Pressure Warning System (TPWS). When performing service that requires tire rotation or tire replacement, suspension component replacement or alignments, the Tire Pressure Warning System must be re-initialized.
During initialization, the Tire Pressure Warning System, located within the ABS or Skid Control ECU, learns the tire sizes from rotational speeds and resonance frequencies.
Once the system has initialized, if tire pressures drop, the TPWS light will illuminate.
If the initialization of the Tire Pressure Warning System is not conducted correctly, the low tire message indicator on the combination meter display may illuminate without a noticeable change in tire pressure. Always initialize the system using the procedures listed in this TSB.
Applicable Vehicles:
^ 2004 - 2005 model year Highlander, RAV4, Sienna, and Solara vehicles equipped with VSC.
^ 2005 model year Scion tC vehicles equipped with ABS.
Warranty Information
Initialization Conditions:
The Tire Pressure Warning light can illuminate requiring initialization if any of the following changes occur:
^ When air pressure is adjusted up or down.
^ When the tires are rotated.
^ When one or more tires are replaced.
^ When suspension components (i.e., struts, shocks, springs, knuckle) are replaced.
^ When an alignment is performed.
NOTE:
Depending on the vehicle owner's driving patterns, habits, and trip duration, initialization of the TPWS may take a significant amount of driving, with several trips, to complete initialization. For this reason, the initialization should be completed by the customer during normal driving conditions.
Reset/Re-initialization Procedure
Following are procedures for a simple reset, such as when the light comes on due to low tire pressure, and for a re-initialization, necessary when tires are rotated or replaced.
Procedure
1. Confirm that the tire pressure is set to the exact specifications printed on the label in the driver's door jamb.
2. With the vehicle parked, turn the ignition switch to the "ON" position.
3. Determine if the system must be reset or re-initialized.
Reset - The system requires "reset" after the light is "ON" and air pressures have been adjusted or a flat repair was performed and the same tire has been reused. (If the tire was replaced, initialization must be performed.)
Re-initialization The system requires "initializing" after tire, wheel or suspension component replacement, after alignment, or after rotating the tires.
A. To reset the TPWS (does not require initialization), press the TPWS "SET" button, hold for 1 - 2 seconds until the TPWS light turns off, and then release the button.
^ This resets the tire pressure system monitor.
B. To re-initialize the TPWS, such as after rotating or replacing tires, press and hold the TPWS "SET" button until the TPWS light blinks 3 times in 1 second intervals. Release the "SET" button after the light completes 3 blinks.
^ This clears all memorized system data and starts the initialization process. After this procedure has been performed, it will be necessary to drive the vehicle to complete the initialization process.
System Limitations
Tire Pressure Warning System (TPWS)
If the following conditions exist, low tire pressure may not be detected and initialization may not be completed:
^ Initialization was not performed correctly after replacing or rotating tires or wheels.
^ The tire inflation pressure is excessively higher than specified, or tire inflation pressure suddenly drops due to bursting or other cases.
^ The vehicle uses snow tires, compact spare tires, or snow chains.
^ The vehicle is being driven on a slippery road surface, such as rough or frozen road.
^ The vehicle speed is less than 19 mph (31 km/h) or more than 62 mph (100 km/h).
^ On one or more tires, the tire tread pattern or manufacture are different from the others.
^ The tires are not the specified size.
^ The tread wear is very different among the installed tires.
^ The pressure of two or more tires drops at the same time.
^ Driving with rapid acceleration/deceleration or sharp turns.
^ The vehicle is overloaded.
^ Ambient temperature is below 32°F (0°C) or above 104°F (40°C).
^ The tires encountered impact on a pot hole or other road irregularity.
^ Aftermarket (non-factory) wheels and tires are installed on vehicle.
If any of these conditions exist, the TPWS may not properly function and the indicator light may give a false indication.
Most Common Conditions for TPWS Light to Come On (listed in order)
1. Improper or incomplete initialization (most common).
2. Tire pressure loss valve stem loose or improperly seated.
3. Wire harness damage or poor connection.
4. Skid Control ECU the TPWS monitor is integrated into the Skid Control ECU, which is attached to the brake actuator assembly (rare condition).
5. Ambient Temperature Sensor (VSC models) can be verified if there is no change in the displayed value when the vehicle is moved to different locations with different temperatures (for example, from cold weather parking lot to warmer repair shop).