Toyota CH-R Service Manual: System Description

Toyota CH-R Service Manual / Tire Pressure Monitoring / Tire Pressure Warning System / System Description

SYSTEM DESCRIPTION

DESCRIPTION OF SYSTEM

(a) The tire pressure warning system warns the driver when the tire pressure has decreased in order to decrease CO2 emissions and enhance safety.

(b) The tire pressure warning system illuminates the tire pressure warning light to warn the driver when the following condition is met:

Due to the operation of the steering pad switch assembly, the tire pressure drops to approximately 75% or less of the tire pressure set during system initialization.
HINT:

The tire pressure warning pressure (pressure at which the tire pressure warning light is illuminated) cannot be set to approximately 75% or less of a specified tire pressure value.

(c) When the tire pressure warning system detects that the tire pressure of a tire is lower than the threshold, it will inform the driver using a warning light.

(d) The tire pressure warning ECU 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.

*A	w/ Full Size Spare Tire	-	-
*1	Tire Pressure Warning ECU and Receiver	*2	Tire Pressure Warning Valve and Transmitter
*3	Combination Meter Assembly - Tire Pressure Warning Light	*4	Main Body ECU (Multiplex Network Body ECU)
*5	Steering Pad Switch Assembly	-	-
*a	Front	-	-

DESCRIPTION OF REGISTRATION

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

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

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TIRE PRESSURE WARNING RESET SWITCH

(a) By operating the steering pad switch assembly, the tire pressure warning ECU and receiver can be set to issue a warning at an inflation pressure that corresponds to the type of tires fitted to the vehicle. Therefore, the warning threshold must be set to the proper value in order to comply with local regulations.

(b) After the inflation pressures of all tires (except the compact spare tire) have been adjusted to the appropriate tire pressures, operate the steering pad switch assembly and perform initialization.

DESCRIPTION OF INITIALIZATION

(a) During initialization, the tire pressure warning valve and transmitters measure the inflation pressure of the tires, and register the signals that are transmitted into the tire pressure warning ECU and receiver at a frequency of about once per minute. The initialization process is completed when signals from all tires (except the compact spare tire) have been received.

(b) Perform initialization in the following cases:

(1) Before delivery of a new vehicle.

(2) After replacement of the tire pressure warning ECU and receiver*.

(3) After replacement of a tire pressure warning valve and transmitter*.

(4) When the specified tire pressure changes due to the use of a different size or type of tire.

(5) When the specified tire pressure changes due to a change in the vehicle load, the speed range that the vehicle will be used in, etc.

(6) When a tire rotation is performed and the specified tire pressures are different for the front and rear of the vehicle.

HINT:

*: Perform initialization after the transmitter ID registration is completed.

FUNCTION OF MAIN COMPONENTS

Component	Function
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 ECU and receiver.
Tire Pressure Warning ECU and Receiver	Receives data from each tire pressure warning valve and transmitter and monitors the tire pressures. When the tire pressure warning ECU and receiver detects a drop in the tire pressure, a system malfunction, or initialization mode, it outputs the respective signal to the combination meter assembly. When the tire pressure warning ECU and receiver 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.
Steering Pad Switch Assembly	Switch that operates the multi-information display. "ENTER" switch: By operating this switch, a tire pressure warning threshold based on the current tire pressure is memorized as the set tire pressure in the tire pressure warning ECU and receiver.
Combination Meter Assembly	Transmits the vehicle speed signal to the tire pressure warning ECU and receiver.
Tire Pressure Warning Light	Illuminates after blinking for 1 minute to warn the driver in accordance with the signal from the tire pressure warning ECU and receiver. Displays 2-digit Diagnostic Trouble Codes (DTCs).
Main Body ECU (Multiplex Network Body ECU)	The main body ECU (multiplex network body ECU) and tire pressure warning ECU and receiver are connected using 2 direct lines that they use to communicate with each other. The main body ECU (multiplex network body ECU) is connected to the combination meter assembly via CAN bus.

System Diagram

SYSTEM DIAGRAM HINT: Each tire pressure warning valve and transmitter sends its transmitter ID, temperature and tire pressure information to the tire pressure warning ECU and receiver. ...

How To Proceed With Troubleshooting

CAUTION / NOTICE / HINT HINT: Use the following procedure to troubleshoot the tire pressure warning system. Make sure that the wireless door lock control system has exited diagnostic ...

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