Acura RL. Manual - part 840

to verify pressure sensor IDs every time the engine starts. It also receives signals from the transmitters in the
tire pressure sensors, and it continuously monitors and controls the system.

Indicators

All indicators are in the gauge control module: The low tire pressure indicator (LED indicator), tire(s)
indicators (on the multi-information display) to show which tire is affected, and the TPMS indicator (on the
multi-information display) that comes on only if there's a problem with the system. When two or more tire
pressures are low, the low pressure indicator comes on about 5 seconds before the appropriate tire(s)
indicator. Once low pressure is detected, the system scans all four pressure sensors to ensure that it turns on
the correct tire indicator.

Fig. 9: TPMS Control Unit - System Diagram
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Tire pressure sensor

Each sensor is an integrated unit made up of the tire valve stem, a pressure sensor, and a transmitter. The
unit is attached to the inside of the wheel, around the valve stem. The sensor transmits a signal to the control
unit when tire pressure is less than 168 kPa (1.7 kgf/cm

,24 psi). The control unit then turns on the low

pressure indicator and the appropriate tire(s) indicator. When that tire's pressure is increased to more than
198 kPa (2.0 kgf/cm

, 29 psi), the transmitter stops sending the signal, and the control unit turns the

indicators off.

Wheels

TPMS (included with PAX system) will not work unless TPMS type wheels are installed on the vehicle. The

2007 Acura RL

2005-08 SUSPENSION TPMS (Tire Pressure Monitoring System) - RL

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original equipment wheels have a "TPMS" or "PAX System" mark on them (A), and a counterweight (B)
cast into the opposite side of the spoke to balance the weight of the sensor (C).

Fig. 10: Identifying Counterweight And Weight Sensor
Courtesy of AMERICAN HONDA MOTOR CO., INC.

System Communication



When the vehicle is running, an RF (radio frequency) band wave signal is continuously transmitted
from the tire pressure sensor to the control unit.



When the ignition switch is turned ON (II), the initiators send an LF (low frequency) band wave
signal to the low pressure sensors, switching them from sleep mode to normal function mode. When
the ignition switch is turned OFF, the sensors switch from normal function mode back to sleep mode
to extend their battery life.



Each low pressure sensor has its own ID to prevent jamming by similar systems on other vehicles.
After memorizing all the sensor IDs, the control unit receives only those specific signals.



An ID can be memorized manually or automatically. Each initiator is hardwired to the control unit.
Every time the ignition is turned ON (II), the control unit asks each initiator for a sensor ID. The
initiators then transmit the sensor IDs, and the control unit receives and memorizes them. The control
unit then knows which ID belongs to each tire location. This recurring ID confirmation prevents any
confusion in the system as a result of normal tire rotation.

NOTE:

Be careful not to bend the bracket or base on the TPMS control unit and
initiators Misalignment of the control unit and initiators could interfere with
sending and receiving signals.

2007 Acura RL

2005-08 SUSPENSION TPMS (Tire Pressure Monitoring System) - RL

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Fig. 11: Identifying Control Unit And Tire Pressure Sensor
Courtesy of AMERICAN HONDA MOTOR CO., INC.

CIRCUIT DIAGRAM

2007 Acura RL

2005-08 SUSPENSION TPMS (Tire Pressure Monitoring System) - RL

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Fig. 12: TPMS - Circuit Diagram (1 Of 3)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

2007 Acura RL

2005-08 SUSPENSION TPMS (Tire Pressure Monitoring System) - RL

Friday, June 05, 2009 3:22:24 PM

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