Toyota 4Runner: System Description

Toyota 4Runner Service Manual / Suspension / Tire Pressure Monitoring / Tire Pressure Warning System / System Description

SYSTEM DESCRIPTION

1. DESCRIPTION OF SYSTEM

(a) When the tire pressure warning system detects that the tire pressure of a tire is below the threshold, it illuminates the tire pressure warning light to warn the driver.

(b) The tire pressure warning antenna and receiver receives the transmitter ID, temperature and tire pressure information from the tire pressure warning valve and transmitters shown in the following illustration. This information is used to determine when the pressure in one of the tires has dropped.

Text in Illustration

*A	w/ Spare Tire Pressure Warning Valve and Transmitter	-	-
*1	Tire Pressure Warning Antenna and Receiver	*2	Tire Pressure Warning Valve and Transmitter
*3	Combination Meter Assembly - Tire Pressure Warning Light	*4	Tire Pressure Warning ECU
*a	Front	-	-

2. DESCRIPTION OF REGISTRATION

(a) When tires and wheels are replaced, always make sure that each transmitter ID is correctly registered.

(b) When one or more tire pressure warning valve and transmitters or the tire pressure warning ECU is replaced, the transmitter IDs for all of the tire pressure warning valve and transmitters must be reregistered. Before registering the transmitter ID of a new tire pressure warning valve and transmitter, check the Data List and record all of the transmitter IDs that are already registered.

3. FUNCTION OF MAIN COMPONENTS

Component	Function
Tire Pressure Warning ECU	Receives the data from the tire pressure warning antenna and receiver and monitors the tire pressure. When the tire pressure warning ECU detects a drop in the tire pressure or a system malfunction, it outputs the respective signal to the combination meter. When the tire pressure warning ECU detects a problem with the vehicle speed signal, it uses changes in the signal strength from the tire pressure warning valve and transmitter as a judgment standard. If the ECU detects any changes in the signal strength from the tire pressure warning valve and transmitter, it determines that the vehicle is being driven.
Tire Pressure Warning Valve and Transmitter	Detects the pressure and internal temperature of the tire and transmits the measured values and the ID code to the tire pressure warning antenna and receiver.
Tire Pressure Warning Antenna and Receiver	Receives the tire pressure warning valve and transmitter signal and transmits this data to the tire pressure warning ECU.
Tire Pressure Warning Light	Illuminates or turns on after blinking for 1 minute to warn the driver in accordance with the signal from the tire pressure warning ECU. Outputs the 2-digit Diagnostic Trouble Code (DTC).

System Diagram

SYSTEM DIAGRAM HINT: The tire pressure warning valve and transmitter sends information on the temperature inside the tire, ID and tire pressure. ...

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