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Special switch resets warning thresholds on Prius

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Special switch resets warning thresholds on Prius

SUBJECT VEHICLE: 2006-13 Toyota Prius.

RELEARN PROCEDURE? Yes, see Reset procedures.

SPECIAL TOOLS NEEDED? Yes, a Toyota Techstream.

The Tire Pressure Monitoring System (TPMS) on the 2006-09Toyota Prius is designed to provide warning when tire inflation pressure of one or more tires is low. A tire pressure monitor valve sub-assembly equipped with a tire pressure sensor/transmitter is installed in each tire and wheel assembly.

NOTE: The system will need to be initialized when tires are replaced with tires of different pressures; tire pressure sensor and/or tire pressure monitor ECU are replaced. When a tire pressure sensor and/or tire pressure monitor ECU are replaced, the sensor ID must be memorized by the tire pressure monitor ECU prior to system initialization. See reset procedures.

The sensor measures the air pressure of the tire, then the measured value and transmitter ID are transmitted to the tire pressure monitor antenna and receiver assembly on the body as radio waves. These radio waves are then sent to the tire pressure monitor ECU from the tire pressure monitor receiver.

If the transmitter ID has already been registered, the ECU compares the measured air pressure value and the standard value. When the value is less than the standard value registered in the tire pressure monitor ECU, the tire pressure warning light on the instrument cluster will turn on. In order to reset the warning threshold in accordance with variant tire pressure settings due to tire types and installation positions, a tire pressure warning reset switch is used. This switch is used to initialize system after certain repair procedures.

NOTE: Due to the air valve angle of the tire pressure warning valve and transmitter, they may not be used on wheels other than those originally installed on the vehicle.

Under the following conditions, the system may not function properly:

• the areas, facilities or devices that use similar radio wave frequencies are located in the vicinity of the vehicle;

• a radio device of similar frequency is used near the vehicle;

• a lot of snow or ice is stuck to the vehicle, especially around the wheels or wheel housings;

• tires and wheels are installed that are not equipped with a tire pressure sensor;

• snow tires or tire chains are used;

• the battery of the sensor has been depleted;

• wheels other than manufacturer factory wheels are used (if any other wheels than the specified ones are used, the system may not function properly because the radio waves are differently transmitted from the tire pressure sensor);

• depending on the tire type, the system may not function properly even though the specified wheels are used;

• using a different type of tire in combination with genuine tires; and

• if the system was initialized with tire pressures which are not the specified values.

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Tire pressure monitor warning light

NOTE: The tire pressure warning light may turn on due to natural causes such as natural air leaks or tire pressure changes caused by temperature. In this case, adjusting the tire pressure will turn off the warning light.

NOTE: If the warning light turned on due to very low outside temperatures (such as in winter) causing decreases in tire pressure, adjust the pressure to a higher pressure suitable to cold conditions. Tire pressure decreases by about 1.45 psi (10 kPa) for every 50 degrees Fahrenheit (10 degrees Celsius) drop in ambient temperature.

When the tire pressure warning light does not go off, or when it comes on during driving, check the tire pressure and adjust as necessary. The warning light should turn off within a few minutes. If the warning light is still on even though the tire pressure is correctly adjusted, the tire could be punctured. Repair as necessary.

If the warning light turns on within several hours after adjusting the tire pressure, the tire may have a slow air leak. If the warning light is still on or blinks, there is a malfunction in the TPMS. See appropriate manufacturer service information.

Reset procedures

NOTE: The system will need to be initialized when tires are replaced with tires of different pressures; tire pressure sensor and/or tire pressure monitor ECU are replaced. See initializing tire pressure monitor system. When a tire pressure sensor and/or tire pressure monitor ECU are replaced, the sensor ID must be memorized by the tire pressure monitor ECU prior to system initialization. See tire pressure sensor registration.

When the tire pressure warning light does not go off, or when it comes on during driving, check tire pressure and adjust as necessary. The warning light should turn off within a few minutes.

NOTE: If the negative battery terminal is disconnected, initialize the following system after the terminal is reconnected: Power Window Control System. Refer to the owner's manual or appropriate manufacturer service information.

Initializing TPMS

NOTE: The system will need to be initialized when tires are rotated; tires are replaced with tires of different pressures; tire pressure sensor and/or tire pressure warning ECU are replaced. If tire pressure sensor and/or tire pressure warning ECU were replaced, ensure that tire pressure sensor IDs are registered <I>prior</I> to initialization. See tire pressure sensor registration.

CAUTION: DO NOT operate the reset switch without adjusting the tire inflation pressure of all tires. Otherwise, the low tire pressure warning light may not come on even if the tire pressure is low, or it may come on when the tire inflation pressure is actually normal. If you push the reset switch while the vehicle is moving, initialization is not performed.

NOTE: When initializing the system, the present tire condition is stored as a standard. During initialization, the tire pressure sensor measures the inflation pressure of the tires, and registers the signals that are transmitted into the tire pressure warning ECU at a frequency of one per minute. The initialization process is completed when the signals from all tires have been received.

The initialization process is canceled if the ignition switch is turned to the OFF position during initialization. To initialize again, the tire pressure warning reset switch must be pressed again.

1. Set the tire pressure of all wheels to the pressure specified on the tire and loading information label.

2. Turn the ignition switch to the ON position.

3. Press and hold the tire pressure warning reset switch until the tire pressure warning light blinks three times at one-second intervals.

4. Connect the Toyota Techstream to the DLC3.

5. Enter the following menus: Chassis/Tire Pressure Monitor/Data List.

6. Confirm that the expected tire pressure data of all tires are displayed on the Techstream screen in order to check the completion.

NOTE: Initialization is normally completed within five to six minutes.

NOTE: If the initialization has not been completed successfully, DTC C2177/77 is set after the vehicle is driven for 20 minutes or more.

NOTE: The initialization can be terminated by connecting terminals 13 (TC) and 4 (CG) of the DLC3.

Tire pressure sensor registration

NOTE: When a tire pressure sensor and/or tire pressure monitor ECU are replaced, the sensor ID must be memorized (registered) by the tire pressure monitor ECU prior to system initialization. To perform this procedure, a Toyota Techstream must be used. It is not necessary to register the sensor ID(s) when only tire rotation is performed.

NOTE: Before beginning the registration process on vehicles where tire pressure sensors have not been replaced, retrieve sensor transmitter ID(s) using the Techstream or by reading the ID on the tire pressure sensor. If sensor is being replaced with a new one, make a note of the seven-digit number (transmitter ID) before installation, as it cannot be seen after sensor is installed (see Figure 1).

1. Set the tire pressure of all wheels to the pressure specified on the tire and loading information label.

2. With the ignition switch OFF, connect the Techstream to the DLC3.

3. Turn the ignition switch to the ON position.

4. Enter the following menus: Chassis/Tire Pressure Monitor/Utility/ID Registration.

NOTE: If this step is not completed within 300 seconds, registration mode will be canceled.

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5. Perform the procedures displayed on the Techstream.

NOTE: It may take about two to three minutes to update the tire pressure data. If the values are not displayed after several minutes, perform troubleshooting according to the inspection procedure for DTCs C2121/21 to C2124/24. If the IDs have not been registered, DTC C2171/71 is set after three minutes or more.

6. Confirmation of transmitter ID registration:

a. Enter the Techstream menu items in this order: Chassis/Tire Pressure Monitor/Data List.

b. Confirm that the expected tire pressures of all tires are displayed on the screen.

Demounting/mounting procedures

CAUTION: The tire should be demounted from the wheel using the tire changer manufacturer's instructions. Use the following information to avoid damage during the demounting/mounting procedures.

NOTE: The system will need to be initialized when tires are replaced with tires of different pressures; tire pressure sensor and/or tire pressure monitor ECU are replaced. When a tire pressure sensor and/or tire pressure monitor ECU are replaced, the sensor ID must be memorized by the tire pressure monitor ECU prior to system initialization. See reset procedures.

NOTE: If the negative battery terminal is disconnected, initialize the Power Window Control System after the terminal is reconnected. Refer to the owner's manual or appropriate manufacturer service information.

Tire pressure sensor

CAUTION: DO NOT try to install a tire pressure sensor in a steel wheel or aftermarket wheel. Due to the unique air valve angle of the tire pressure sensor, use only in original style factory wheels.

CAUTION: The use of tire sealants is strictly prohibited for vehicles equipped with TPMS. Tire sealants can clog tire pressure sensors.

CAUTION: Be sure to reinstall tire valve caps, or dirt or moisture could get into the valve core and cause air leakage. Use only the original valve cap. If any other valve cap is used, it may corrode or melt, and become extremely difficult to remove.

NOTE: The average life of the grommet of the tire pressure sensor is approximately five years, at which time it must be replaced. If the valve is leaking air but it is less than five years old and the grommets are in good condition, retighten the valve nut to 35 in.-lbs. (4 N.m). Whenever the tires must be replaced, replace grommets for tire pressure sensors as well.

NOTE: If the tire pressure valve sub-assembly is going to be replaced, make a note of the seven-digit number (transmitter ID) before installation, as it cannot be seen after sensor is installed (see Figure 1). Whenever a new sensor is installed, it will need to be registered in the tire pressure monitor ECU.

Removal

1. When replacing a wheel or tire, tire pressure sensors must be set up in one of the following ways:

• remove the sensor from the old wheel and install it to the new wheel;

• keep the same wheel with tire pressure sensor, and replace only the tire; and

• use a new wheel and sensor (the new sensor must be registered after installation).

2. Remove the wheel. Remove the valve core and cap, and release the air from the tire (see Figure 2).

NOTE: Keep the removed cap, valve core, nut and washer.

3. After ensuring that air is sufficiently released, remove the nut and washer that is used to fix the tire pressure sensor and drop the sensor inside the tire.

NOTE: Be careful not to damage the tire pressure sensor due to interference between the sensor and tire bead.

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4. After dropping the tire pressure sensor into the tire, disengage the bead using the shoe of the tire remover.

5. Remove the bead on the upper side in the usual operation.

6. Take out the sensor from the tire, and remove the bead on the lower side as in usual operation. NOTE: Check that no cracks or damage is identified on the grommet. If so, replace the grommet together with the washer and nut.

7. Remove the inner grommet from the tire pressure sensor. NOTE: Tire pressure sensor is powered by a lithium battery. When disposing of a sensor, remove the battery and dispose of properly.

Installation

1. Insert the tire pressure monitor valve into the valve installation hole. Insert from the inside of the rim so that the print surface can be seen (see Figure 1). Check for the following:

• check that there is no visible deformation, damage or other abnormalities on the transmitter;

• check that there is no foreign matter on the inner grommet and around the rim hole;

• if installed in the reverse direction, the tire pressure monitor valve may be damaged or fail to transmit signals when running at high speed; and

• if installing a new tire pressure monitor valve, write down the ID number before installation (see Figure 1); it is necessary to register an ID in the ECU after installation.

2. Install the washer on the tire pressure monitor valve from the rim side, and tighten the nut to 35 in.-lbs. (4 N.m) (see Figure 3). Check for the following:

• ensure there is no foreign matter on the washer and nut;

• if the tire pressure monitor valve was removed, check that there is no damage or cuts, and no foreign matter such as mud, dirt or sand attached to the grommet; replace the grommet with a new one if any of these defects are found; and

• check that there is no oil, water or lubricant around the rim hole, tire pressure monitor valve, washer and nut, as failing to do so may result in improper installation.

NOTE: The specified torque only applies the first time washer is used.

3. After the tire is inflated, the valve nut may be loose. Retighten the nut to the specified torque, and then check for air leaks with soapy water. CAUTION: If the sensor is positioned outside this area, it generates interference with the tire bead, causing possible damage to the sensor.

4. Set the wheel disc to the mounting machine, and install the lower tire bead. Position the main body of the sensor in the shaded area as shown in Figure 4.

5. Making sure that the tire bead and tool do not interfere with the main body of the sensor and that the sensor is not clamped by the bead, install the upper bead.

6. When putting air into the tire, first install the tire pressure valve straight on the stem of the tire pressure warning valve and transmitter.

7. Install the tire and wheel assembly.

8. When a new sensor is installed, the ID code will need to be registered.

See tire pressure sensor registration under reset procedures.

9. After completing the operation, remove the valve core to rapidly release the air in the tire. Ensure the tire pressure warning light comes on. If warning light does not come on, refer to the appropriate manufacturer service information.

10. If there is an air leakage, tighten the nut to a force of 35 in.-lbs. (4 N.m), and push the valve core two to three times to remove any dirt attached to the valve core. If air continues to leak, replace the grommet, washer and nut.

Information for this column comes from Mitchell 1’s “Tire Pressure Monitoring Systems Guide” for domestic and import vehicles through 2012. Headquartered in Poway, Calif., Mitchell 1 has provided quality repair information solutions to the automotive industry for more than 80 years. For more information, visit www.mitchell1.com.

Want more articles on TPMS? See also:

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