LaCrosse V6-3.6L VIN 7 (2006)
Low Tire Pressure Indicator: Description and Operation
TIRE PRESSURE MONITOR DESCRIPTION AND OPERATION
The Tire Pressure Monitor (TPM) system alerts the driver when a large change in pressure of one tire exist, while the vehicle is being driven. The
TPM system uses the Electronic Brake Control Module (EBCM), ABS wheel speed sensor inputs, class 2 serial data circuit, Instrument Panel Cluster
(IPC) message center, and the Driver Information Center (DIC) to perform the system functions. The EBCM contains the software to calculate relative
tire pressure differences. The software requires up to 8 km (5 miles) of straight line, smooth road driving in each of the 4 speed ranges to complete the
calibration process in order to have any capability for detecting a tire pressure condition. The speed ranges are as follows:
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31-65 km/h (19-40 mph)
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65-95 km/h (40-59 mph)
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95-120 km/h (59-74.5 mph)
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120-145 km/h (74.5-90 mph)
Each of the speed ranges have 2 modes of operation:
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Calibration
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Detection
In calibration mode the TPM system is learning the tire pressure calibrations and can not detect a low tire pressure condition. In detection mode the
TPM system has learned the tire pressure calibration and can detect a low tire pressure condition. The EBCM learns the tire pressure calibration for
each speed range independently. Once the TPM system has learned the tire pressure calibration the EBCM monitors the ABS wheel speed sensor
inputs, which will all be the same as the learned calibration if the tire pressures stay the same. If the pressure increases or decreases in one tire, so too
will that tires circumference, radius, and diameter, which causes that wheel speed sensor input to change. The EBCM recognizes this change in wheel
speed as a tire pressure condition. If the pressure in one tire becomes at least 48-69 kPa (7-10 psi) lower or higher than the other three the EBCM
commands the DIC and the IPC message center to display The LOW TIRE PRESSURE warning message via a class 2 serial data circuit. The IPC
message center LOW TIRE PRESSURE warning message is a Re-configured Telltale and is ranked as lowest priority and may not be displayed if a
higher priority display is requested at the same time. The system does not alert the driver to which tire is high or low. The warning messages do not
appear in either display if any of the following conditions are present:
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More than one tire is high or low.
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The system is not fully calibrated.
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Vehicle speed is above 112 km/h (70 mph).
If the tire pressures are at the specified psi the TIRE PRESSURE NORMAL message is displayed when selected on the DIC. To clear the LOW TIRE
PRESSURE warning message, refer to service and repair.
