Terrain FWD L4-2.4L (2010)
Tire Pressure Sensor: Testing and Inspection
Tire Pressure Indicator Sensor Learn
Special Tools
J-46079 Tire Pressure Monitor Diagnostic Tool
Relearn Mode Description
The tire pressure monitor (TPM) system uses the instrument panel cluster (IPC), body control module (BCM), 4 radio frequency transmitting pressure
sensors, and the serial data circuit to perform the TPM Relearn mode functions. The sensor Relearn procedure must be performed after every tire
rotation, BCM replacement, or sensor replacement. Once the relearn mode has been enabled, each of the sensors unique identification codes can be
learned into the BCM memory. When a sensor ID has been learned, the BCM sends a serial data message to the BCM to sound a horn chirp. This
verifies the sensor has transmitted its ID and the BCM has received and learned it. The BCM must learn the sensor IDs in the proper sequence to
determine correct sensor location. The first learned ID is assigned to the left front location, the second to right front, the third to right rear and the fourth
to left rear. The turn signals will individually illuminate indicating which location is to be learned in the proper sequence.
Sensor Functions Using J-46079 or EL-46079
Each sensor has an internal low frequency coil. When the J-46079 is used in activate mode, it produces a low frequency transmission that activates the
sensor. The sensor responds to a low frequency activation by transmitting in learn mode. When the BCM receives a learn mode transmission while in
TPM learn mode, it will assign that sensors ID to the location on the vehicle relative to the order in which it was learned.
Sensor Functions Using Pressure Increase/Decrease Method
Each sensor takes a pressure measurement sample once every 30 seconds while in stationary mode. If the tire pressure increases, or decreases by more
than 8.3 kPa (1.2 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 transmits in Learn mode. When the BCM receives a Learn mode transmission while in TPM learn mode, it will
assign that sensor's ID to the location on the vehicle relative to the order in which it was learned.
Relearn Mode Cancellation
The Relearn mode will cancel if the ignition is cycled to OFF or if more than 2 minutes has elapsed for any sensor that has not been learned. If the
relearn mode is cancelled before the first sensor is learned, the original sensor IDs will be maintained. If the relearn mode is canceled after the first
sensor is learned, the following will occur:
*
All stored sensor IDs will be invalidated in the BCM memory.
*
If equipped, the DIC will display dashes instead of tire pressures.
*
DTC C0775 will be set.
These conditions will now require the relearn procedure to be repeated for the system to function properly.
TPM Relearn Procedure
Note: If using the scan tool to enable the relearn mode, the J-46079 must be used to activate the sensors. When this preferred method is used, any stray
sensor signals will not affect the relearn procedure. In the event a particular sensor's information is displayed on the special tool upon activation but the
horn does not chirp, it may be necessary to rotate the wheel valve stem to a different position due to the sensor signal is being blocked by another
component.
If using the DIC buttons to enable the relearn mode, the J-46079 or Pressure Increase/Decrease Method may be used. Before proceeding with this
method, ensure that no other learn procedure is being performed simultaneously or that tire pressures are not being adjusted on another TPM equipped
vehicle within close proximity. Stray signals from other TPM equipped vehicles just driving by can be inadvertently learned. If any random horn chirps
are heard from the vehicle while performing the learn procedure, most likely a stray sensor has been learned and the procedure will need to be cancelled
and repeated. Under these circumstances, performing the TPM Relearn Procedure away from other vehicles would be highly recommended. In the event
a particular sensor activation does not cause the horn to chirp, it may be necessary to rotate the wheel valve stem to a different position due to the sensor
signal is being blocked by another component.
Preferred Scan Tool Relearn Enable Method
1. Apply park brake (manual transmission only).
2. Ignition ON, using a scan tool, initiate the Tire Pressure Sensors Learn mode. A double horn chirp will sound indicating the Relearn mode has
been enabled. The left front turn signal will also be illuminated.
3. Starting with the left front tire, active the sensor by holding the antenna of the J-46079 aimed upward against the tire sidewall close to the wheel
rim at the valve stem location. Press and release the Activate button and wait for a horn chirp. Once the horn chirp has sounded, the sensor
information is learned and the turn signal in the next location to be learned will illuminate.
