DESCRIPTION & OPERATION
NOTE: When directed to train any TPMS sensors, use only the sensor training procedure outlined in this repair information. Do not use the TPMS reset procedure outlined in the owner's literature as this procedure does not program new sensors to the module.
The TPMS uses four valve-stem-mounted sensors to monitor tire pressure. These sensors transmit tire pressure data to the Radio Transceiver Module (RTM). Each individual sensor contains its own battery and transmits tire pressure data to the RTM. The RTM collects the tire pressure data and sends the information along the MS-CAN to the Gateway Module (GWM) which then sends the information to the Body Control Module (BCM) along the HS-CAN1. All TPMS functions are controlled by the BCM. The TPMS sensors are trained (calibrated) to the BCM, which records the unique identifier for each sensor. The BCM records the location of each TPMS sensor based on the training (calibration) order and compares the tire pressure data sent by the sensors with a programmed tire pressure. This programmed pressure is specified on the VC label. If the tire pressure deviates from the programmed tire pressure, the BCM, using the MS-CAN, signals the IPC to illuminate the TPMS warning indicator and display a message in the message center. The programmed tire pressure cannot be changed.
The diagnostic scan tool is useful in diagnosing TPMS concerns and may be used to verify the accuracy of the tire pressure data transmitted by the TPMS sensors. This is accomplished by comparing the BCM tire pressure PID data to the actual tire pressure using a digital tire pressure gauge. It is not necessary to train the sensors after a tire rotation on vehicles with the same front and rear tire pressures however, the BCM cannot recognize the sensor identifiers have been moved to different positions and retains the original position information for each sensor.
Wheel rotation and sensor training techniques
Training known good sensors from another vehicle can help determine whether the concern is with a sensor or the RTM. This technique cannot help determine whether the concern is due to RFI as some RFI source could be preventing the RTM from receiving the tire pressure status from the known good sensors as well as the original sensors. If the RTM in the suspect vehicle cannot train any of the original sensors and, likewise, cannot train known good sensors from another vehicle, then the concern is with the module or RFI and not with the original sensors. The original sensors should not be replaced.
If a sensor in a certain location has caused several events, yet the sensor trains and seems to operate normally, moving that particular wheel to a different location on the vehicle is a good way to isolate the concern to a certain sensor/wheel location. Rotate the wheels and road test the vehicle. This can be done in an attempt to replicate the concern and help determine if the concern followed the sensor or remained in the original sensor location. If the vehicle has been stationary for more than 30 minutes, the sensors go into a "sleep mode" to conserve battery power and need to be "woken up" so they transmit the latest tire pressure information to the RTM.
Training sensors in a different order
If the first sensor fails the TPMS training procedure, the BCM aborts the entire procedure. Starting the training procedure at a different wheel is a technique that can be used to determine if the remaining sensors can train to the module. This can help save time determining if one sensor is damaged, other sensors are having concerns or the BCM is experiencing training difficulties with a certain TPMS sensor location.
TPMS warning indicator
The TPMS warning indicator is used to indicate both a low tire pressure event and a possible system fault condition. The message center displays additional information associated with the low tire pressure event or the system fault condition. Occasionally, the warning indicator and message center indicate faults that cannot be resolved by the customer. Treat these as TPMS faults that must be serviced.
TPMS warning indicator illuminates continuously
The TPMS warning indicator remains on continuously and the message center displays LOW TIRE PRESSURE when any of the tire pressures fall below the low pressure limit. When this condition exists, adjust the tire pressure to the recommended cold tire pressure indicated on the VC label.
TPMS warning indicator flashes
The TPMS warning indicator flashes for 70 seconds and then remains on continuously when the ignition is set to ON and the TPMS is malfunctioning. The TPMS status PID can be used to determine why the TPMS warning indicator is flashing.
• Tire Pressure Sensor Fault: The message center displays TIRE PRESSURE SENSOR FAULT when a TPMS sensor is malfunctioning.
• No communication with the BCM: The TPMS warning indicator illuminates when the IPC has not received any signals from the BCM for more than five seconds. The message center displays TIRE PRESSURE MONITOR FAULT.
• Tire Pressure Monitor Fault: The message center displays TIRE PRESSURE MONITOR FAULT when the TPMS is malfunctioning.
TIRE PRESSURE SENSOR REMOVAL AND INSTALLATION
DISASSEMBLY
NOTE: Failure to follow the instructions below may result in damage to the TPMS.
The TPMS sensor is mounted to the valve stem. Removal of the valve stem requires demounting the tire from the wheel and removal of the TPMS sensor.
Use only the digital tire pressure gauge any time tire pressures are measured to be sure that accurate values are obtained.
1) Remove the wheel and tire.
NOTE: The valve stem is connected to the TPMS sensor. Do not pull the valve stem from the wheel, or damage to the sensor will occur.
If a new TPMS sensor is being installed, remove and discard the valve stem-to-sensor screw and the sensor.
2) Remove the valve stem core and fully deflate all air from the tire.
NOTE: Do not allow the tire beads to move beyond the wheel mid-plane (middle of the wheel) when separating the beads from the wheels, as damage to the TPMS sensor may occur.
Tire and valve stem position is critical to prevent damage to the TPMS sensor when using a paddle-type bead separator.
Some machines may have a nylon roller bead separator at the 12 o'clock position instead of the paddle-type bead separator at the 3 o'clock position.
3) For a paddle-type tire machine, position the valve stem at the 12 o'clock or 6 o'clock position and the paddle at the 3 o'clock position. For a roller-type tire machine, align the valve stem with the roller at any position.
Index-mark the valve stem and wheel weight positions on the tire.
4) Place the wheel and tire assembly on the turntable of the tire machine with the valve stem at the 11:30 position and the machine arm at the 12 o'clock position and demount the outer bead from the wheel.
5) Reset the wheel and tire assembly on the turntable of the tire machine with the valve stem at the 11:30 position and the machine arm at the 12 o'clock position and demount the inner bead from the wheel.
NOTE: A new valve stem must be installed whenever a new tire or wheel is installed.
6) Remove and discard the TPMS sensor-to-valve stem screw. Separate the TPMS sensor from the valve stem.
NOTE: Use care not to damage the wheel surface when removing the valve stem.
When installing a new wheel, always install a new valve stem and sensor screw. Reuse the TPMS sensor from the previous wheel if possible. The TPMS will not have to be trained if the sensor is reused.
If the TPMS sensor is being reused, inspect the TPMS sensor for damage and install a new sensor as necessary.
7) Using a suitable valve stem remover/installer, remove and discard the valve stem. Use the General Equipment: Wooden Block.
NOTE: To prevent TPMS sensor and valve stem damage, the valve stem must be installed onto the TPMS sensor and then installed into the wheel as an assembly.
8) Position the new valve stem onto the TPMS sensor and install the new screw. Torque: 13 lb.in (1.5 Nm)
ASSEMBLY
NOTE: Damage to the TPMS sensor may result if the tire mounting is not carried out as instructed.
It is important to pull the valve stem and TPMS sensor assembly through the wheel rim hole in a direction parallel to the valve stem hole axis. If the assembly is pulled through at an angle, damage to the valve stem and sensor assembly may occur.
Use care not to damage the wheel surface when installing the valve stem and TPMS sensor assembly.
Lubricate the valve stem with soapy water and install the valve stem and TPMS sensor assembly into the wheel using a block of wood and a suitable valve stem installer.
1) Using a suitable valve stem installer, install the new valve stem and TPMS sensor assembly. Use the general equipment: wooden block.
NOTE: Lubricate the tire beads using a suitable fast-drying, corrosion-inhibiting tire bead lubricant.
Do not mount the tire at this time.
2) Position the wheel on the turntable of the tire machine, then lubricate and position the bottom bead of the tire on the wheel.
3) Position the wheel to align the valve stem with the machine arm, at the 6 o'clock position, and mount the bottom bead of the tire.
4) Reposition the wheel to align the valve stem with the machine arm at the 6 o'clock position, and mount the top bead of the tire.
NOTE: Use only the digital tire pressure gauge any time tire pressures are measured to be sure that accurate values are obtained.
Proceed to the next step if the tire beads do not seat at the specified inflation pressure.
5) Inflate the tire to the pressure specified on the VC label located on the driver door or door pillar.
WARNING: If there is a need to exceed the maximum pressure indicated on the sidewall of the tire in order to seat the beads, follow all steps listed below. Failure to follow these steps may result in serious personal injury.
6) The following steps should only be carried out if the tire beads cannot be seated by inflating the tire up to the maximum inflation pressure listed on the tire sidewall.
· Relubricate the tire bead and wheel bead seat area.
· Install a remote valve and pressure gauge.
· Wear eye and ear protection and stand at a minimum 12 feet away from the wheel and tire assembly.
· Inflate the tire using the remote valve and tire gauge until the beads have seated or until the pressure gauge is 138 kPa (20 psi) more than maximum inflation pressure on tire sidewall. If beads have not seated, deflate the tire and proceed to the next step.
· Place the wheel and tire assembly in an OSHA-approved tire safety cage.
· Inflate the tire using the remote valve and pressure gauge until the beads have seated or until the pressure gauge is 276 kPa (40 psi) more than maximum inflation pressure on the tire sidewall. Do not exceed 276 kPa (40 psi) above the maximum pressure on tire sidewall. Install a new tire if the beads do not seat at this pressure.
· Install the wheel and tire.
TORQUE SPECIFICATIONS
Item Nm lb-ft lb-in
Valve stem-to-TPMS sensor screw 1.5 - 13
