CH-46079 Tire Pressure Monitor Diagnostic Tool

Note: When enabling the learn mode the gear lever for automatic transmission must be in park position. With manual transmission the park brake lever/switch must be in park position.

The tire pressure monitor (TPM) system uses

to perform the TPM learn mode functions. The sensor learn procedure must be performed after every tire rotation, BCM replacement, or sensor replacement. Once the learn 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 sounds a horn chirp and activates all turn signal lamps for 3 seconds. 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 CH-46079

Each sensor has an internal low frequency coil. When the CH-46079 tire pressure monitor diagnostic tool 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 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.

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 transmission, 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.

Learn Mode Cancellation

The learn 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 learn mode is cancelled before the first sensor is learned, the original sensor IDs will be maintained. If the learn mode is canceled after the first sensor is learned, the following will occur:

These conditions will now require the learn procedure to be repeated for the system to function properly.

TPM Learn Procedure

Note: If using the scan tool to enable the learn 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 learn 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.

Preferred Scan Tool Learn Enable Method

1. Using a scan tool, initiate the TPM Learn Mode. A double horn chirp will sound together with activated turn signal lamps indicating the Learn Mode has been enabled. The left front turn signal only will then be illuminated.
2. 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 all the turn signal lamps have been activated for 3 seconds and the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.
3. After the horn chirp has sounded and the turn signal in the next location to be learned will illuminate, repeat step 2 for the remaining 3 sensors in the following order:

1. Right front

2. Right rear

3. Left rear

4. When the left rear sensor has been learned, all the turn signal lamps have been activated for 3 seconds and a double horn chirp has sounded, the learn process is complete and BCM exits the learn mode.
5. Ignition OFF, adjust all tires to the recommended pressures using a reliable measurement unit. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label.

Alternate DIC Learn Enable Method

1. Ignition ON, press and release the driver information center (DIC) INFO button on the stalk switch alternatively press the odometer button (depending on DIC level) until the TIRE LEARN message appears on the DIC display. Press and hold the SET/RESET button until all the turn signal lamps have been activated for 3 seconds and a double horn chirp sounded indicating the Learn Mode has been enabled. The left front turn signal will then be illuminated.
2. Starting with the left front tire, learn the tire pressure using one of the following methods:

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Hold the antenna of the CH-46079 diagnostic tool 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 all the turn signal lamps have been activated for 3 seconds and a single horn chirp sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.

Warning: 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.

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Increase/decrease the tire pressure 8.3 kPa then wait for a horn chirp. The horn chirp may occur before or up to 30 seconds after the pressure increase/decrease. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.

3. After the horn chirp has sounded the turn signal in the next location to be learned will illuminate, repeat step 2 for the remaining 3 sensors in the following order:

1. Right front

2. Right rear

3. Left rear

4. When the left rear sensor has been learned and all the turn signal lamps have been activated for 3 seconds and a double horn chirp has sounded, the learn process is complete and BCM exits the learn mode.
5. Ignition OFF, adjust all tires to the recommended pressures using a known accurate hand held tire pressure gauge. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label.