Alero L4-144 2.4L DOHC VIN T SFI (2000)
Low Tire Pressure Indicator: Description and Operation
Tire Inflation Monitoring System Circuit Description
The Tire Inflation Monitoring (TIM) system alerts the driver of a large change in pressure in one tire. Whenever repairs are done on any of your tires,
(inflate one or more, tire rotation, repair a flat, etc..) or whenever the battery is disconnected, perform the Tire Inflation Monitor Reset Procedure. The
system will then begin to learn the pressure at each tire throughout the operating speed range of the vehicle.
The system takes between 45 and 90 minutes to "learn" the tire pressures, depending upon individual driving habits. Learning need not be
accumulated during a single trip. Once learned, the system will remember until the RESET procedure is performed.
The TIM system is a software driven system. The system uses the existing Antilock Brake System (ABS) components. The Electronic Brake Control
Module (EBCM), wheel speed sensors, serial data line, and the instrument cluster perform the system functions.
The EBCM contains the software to perform the system monitoring functions. The EBCM uses wheel speed data obtained from the wheel speed
sensors to detect relative pressure differences of 12 psi. This means that one tire is at least 12 psi lower in pressure than the other 3 tires. The EBCM
uses only smooth data. Braking and acceleration or deceleration of greater than 0.1g , and/or any ABS system activity causes the EBCM to stop
performing TIM system functions. When the EBCM detects a low tire pressure condition, the EBCM sends a message to the instrument cluster via the
serial data line.
