Low Tire Pressure Warning Module: Notes

The LTPW module has a microprocessor controller that can monitor the transmissions from the transmitters at all times with the ignition on. The LTPW module will store the last 32 transmissions from the tire pressure sensor/transmitters, however, they cannot be observed as they occur with the DRBIII®. There are three important values included in these transmissions. They are listed as: why the transmission was sent, from which sensor it came from (LF, RF, RR, LR), and tire pressure. There are four reasons why the tire pressure sensor/transmitter will send information to the LTPW module they are listed below:

Supervisory - This is the normal mode, the transmitter will start to transmit information to the LTPW module at approximately 33 km/h (20 MPH) and continue at a rate of approximately one transmission per minute.

6.9 kPa (1 psi) Change - If the pressure reading changes by more than 6.9 kPa (1 psi) between the normal sampling period of 30 seconds, the transmitter will send this change information to the LTPW module within approximately 30 seconds.

Wake - This is the very first message that the tire pressure sensor/transmitter sends to the LTPW module. This wake mode will only occur after the vehicle has reached the start to operate speed of approximately 33 km/h (20 MPH).

Magnet - When a magnet is placed next to the transmitter it closes a reed switch inside and forces the transmitter to send a signal to the LTPW module. Placing a magnet next to the transmitter will normally be done for programming purposes when the LTPW module or the tire pressure sensor/transmitter is being replaced.

The module compares the transmitted tire pressure to the two pressure thresholds, low and critical. If the module determines that the tire pressure transmitted is below the low or critical pressure, the module will signal the "Low Tire" Pressure Warning Indicator to come on.

The module performs diagnostic routines, stores diagnostic trouble codes and provides the appropriate Indicator status to the BCM. When the module determines that there is a fault, the low tire pressure signal circuit will be pulled low (grounded) and the BCM will turn on the "Low Tire" lamp.

The LTPW module also stores its own ID number, each of the four transmitter ID numbers, module version and date of manufacture.