J-46079 Tire Pressure Monitor Diagnostic Tool

The tire pressure monitor (TPM) system uses the liftgate module (LGM), body control module (BCM), exterior lamp switch, 4 RF transmitting pressure sensors, and the serial data circuit to perform the TPM learn mode functions. The sensor learn procedure must be performed after every tire rotation, LGM replacement, or sensor replacement. Once the TPM learn mode has been enabled, each of the sensor's unique identification (ID) codes can be learned in to the LGM memory. When a sensor's ID has been learned, the LGM sends a serial data message to the BCM to sound a horn chirp. This verifies the sensor has transmitted its ID and the LGM has received and learned it. The LGM must learn the sensor IDs in the proper order 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.

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 1.6 psi from the last transmitted pressure, another measurement will occur immediately to verify the change in pressure. If a pressure change has indeed occurred, the sensor transmits in re-measure mode. When the LGM receives a re-measure 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.

Sensor Functions Using J-46079

Each sensor has an internal low frequency (LF) coil. When the J-46079 is used in activate mode it produces an LF transmission that activates the sensor. The sensor responds to a LF activation by transmitting in learn mode. When the LGM 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.

TPM Learn Mode Cancellation

The learn mode will cancel if more than 2 minutes have passed and no sensor have been learned, or if more than 5 minutes has passed for the entire procedure. If the learn mode is canceled before any IDs are learned, the LGM will remember all previously stored IDs and their locations. As soon as the LGM learns the first ID, all other IDs are erased from the LGM memory.

Important: Before proceeding with the steps below, verify the following:

1. Turn ON the ignition, with the engine OFF.
2. Apply the parking brake.
3. Cycle the exterior lamp switch from OFF to parking lamps 4 times within 4 seconds. A double horn chirp will sound and the low tire pressure indicator 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.

4. Starting with the left front tire, hold the antenna of the J-46079 against the tire sidewall close to the wheel rim at the valve stem location then press and release the activate button and wait for a horn chirp, or increase/decrease the tire pressure for 8-10 seconds then wait for a horn chirp. 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.
5. After the horn chirp has sounded, proceed as in step 4 for the next 3 sensors in the following order:

5.1.	Right front

5.2.	Right rear

5.3.

Left rear

6. After the LR sensor has been learned, turn OFF the ignition to exit the learn mode.
7. After the learn mode has been exited, adjust all tire pressures to the recommended psi. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label .