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TPMS SYSTEM BACKGROUND - how TPMS is integrated into the vehicle's computer:
The tire pressure monitor (TPMS) system uses the passenger door module (PDM), the body control module (BCM), the exterior lamp switch, the 4 radio frequency transmitting pressure sensors in the tire valves, and the serial data circuit to perform the sensor learn mode functions.
LEARN MODE DESCRIPTION
To read correctly, the sensor learn procedure must be performed any time the PDM is replaced, a tire sensor is replaced, or after the vehicle's tires have been rotated. Once the learn mode has been enabled, each of the sensors' unique identification code can be programmed ("learned") into the PDM's memory. When a sensor's ID code has been learned, the PDM sends a serial data message to the BCM to sound a horn chirp. This verifies the sensor has transmitted it's ID code and the PDM has received it. As soon as the first sensor ID code is learned, all other IDs are erased from the PDM's memory.
Each sensor takes a pressure measurement sample once every 20 seconds while in stationary mode. If the tire pressure increases or decreases by more than 1.6 PSI from the last pressure measurement, another measurement will occur immediately to verify the change in pressure. If a pressure change has indeed occurred, the sensor sends a re-measure signal to the PDM. When the PDM receives a re-measure signal while in sensor learn mode, it will assign that sensor ID to that location on the vehicle.
The PDM must learn each sensor's ID code in the proper sequence in order to determine sensor location.
LEARN MODE CANCELLATION
The TPM system will cancel the learn mode if more then 2 minutes have passed and no sensors have been learned, or if the system has been in learn mode for more than 5 minutes. If the learn mode is canceled before any sensor has been learned, the PDM will remember all current sensor IDs and their locations.
CAUTION: Before proceeding with the steps below, ensure that no other sensor learn procedure is being performed simultaneously, or that tire pressures are not being adjusted on a TPM equipped vehicle within close proximity.
STEP BY STEP:
- Turn "ON" the ignition, with the engine OFF.
- Apply the parking brake. IMPORTANT: If the learn mode cannot be enabled, ensure the TPM system is enabled in the PDM.
- Turn the exterior lamp switch from "OFF" to parking lamps 4 times within 4 seconds. A horn chirp will sound and the low tire pressure light will begin to flash indicating the learn mode has been enabled.
CAUTION: Over inflating tires may cause personal injury or damage to the tires and wheels. When increasing tire pressure do not exceed the maximum inflation pressure as noted on the tire sidewall.
IMPORTANT: If a horn chirp does not sound after 35 seconds for any of the 4 sensors, turn the ignition "OFF" to exit the learn mode and repeat the procedure from step 1.
- Starting with the left front tire, increase or decrease the pressure for 8-10 seconds, or until a horn chirp sounds. The horn chirp may occur before the 8-10 second pressure increase/decrease time period has been reached, or up to 30 seconds after the 8-10 second pressure increase/decrease time period has been reached.
- After the horn chirp has sounded, proceed as in step 4 for the next 3 sensors in the following order: Right front
- After all sensors have been learned, exit the learn mode by turning "OFF" the ignition.
- After the learn mode has been exited, adjust all tire pressures to the recommended psi
- After adjusting all tire pressures to the recommended psi, run the tire pressure check in the DIC to see that the correct pressure is listed.