Tire Pressure Monitoring System
TIRE PRESSURE MONITORING SYSTEMIf equipped with the Tire Pressure Monitoring System, each of the vehicle's five wheels will have a valve stem with a pressure sensor and radio transmitter built in. Signals from the tire pressure sensors are received and interpreted by the Electronic Vehicle Information Center (EVIC).
A sensor in a mounted wheel will broadcast its detected pressure once per minute when the vehicle is moving faster than 40 km/h (25 mph). The spare tire sensor will broadcast once every hour. Each sensor's broadcast is uniquely coded so that the EVIC can determine location. The individual tire pressures can be displayed graphically on the EVIC.
NOTE: The spare tire is only monitored when equipped with the 5-Tire TPM System.
Training The EVIC
The EVIC can be trained to recognize the source locations of pressure sensor signals. The training procedure is given below:
1. Locate "RETRAIN TIRE SENSORS" on the EVIC menu.
When this mode is enabled by selecting "YES", the EVIC will initiate the following procedure.
2. A display will prompt the user to: "TRAIN LEFT FRONT TIRE". At this point the user must set the left front tire sensor to learn mode by positioning a magnet (Relearn Magnet special tool 8821) over the valve stem for at least 5 seconds. The Remote Tire Pressure Monitor (RTPM) in the front left tire will transmit a message indicating to the EVIC that it is in learn mode. When the EVIC has received this message and is assured that it has learned an ID, the EVIC will request a horn chirp via a bus message and then display the next train request. Note: There is a 60 seconds timer for learning the first tire location and a 30 seconds timer between the remaining tires. If any of these timers expire the EVIC will abort the training procedure.
3. The EVIC will request the initiation of a training sequence for each tire, one-by-one in a clockwise direction around the vehicle (Left Front, Right Front, Right Rear, Left Rear and Spare). The EVIC will allow 30 seconds (60 seconds for the first tire) from the beginning of the train request display to the receipt of a unique learn ID message from the RTPM. If, during a training session, a 60 or 30 second timer expires before a unique learn sensor ID is received or the vehicle is not in park, the EVIC will keep the previous set of trained IDs and will display "TRAINING ABORTED" until a button is pressed. Any IDs learned during the current session will be discarded. The EVIC will not store one ID for multiple locations.
NOTE: The spare tire is only monitored when equipped with the 5-Tire TPM System.
4. Once all four (or five) tires are successfully trained, the previous set of stored IDs will be replaced by the new IDs, and the EVIC will display, "TRAINING COMPLETE" until a button is pressed.
If the vehicle is equipped with the Homelink feature and a Homelink button is pressed at any time during the training procedure, the EVIC module will immediately exit the training procedure, discard any IDs learned in the current session and perform the Homelink function. After the button is released, the module will display "RETRAIN TIRE SENSORS? NO".
The training procedure can be stopped at any time by pressing the C/T, STEP RESET or MENU button. When any of these buttons are pressed the EVIC will display "TRAINING ABORTED."
Once training is complete, the EVIC can determine when the spare wheel has been mounted on the vehicle. The spare wheel sensor/transmitter is expected to transmit once per hour. If the sensor/ transmitter ID for the spare wheel is received at a shorter interval, the EVIC will request a chime and display "SPARE SWAP DETECTED" for five seconds.
NOTE: The spare tire message is only available when equipped with the 5-Tire TPM System.
Pressure Thresholds
The EVIC will monitor the tire pressure signals from the four (or five) tire sensors and determine if any tire has gone below the low pressure threshold or raised above the high pressure threshold. Refer to the table below.
Critical And Non-Critical Pressure Alerts
A critical alert will be triggered when a tire pressure has gone below or above a set threshold pressure. Depending on what the condition is, the EVIC will request a chime and then display a LOW PRESSURE or HIGH PRESSURE message indicating the appropriate location.
The alert message will display for three seconds and then switch to the tire pressure trip screen. The tire pressure for the tire that has exceeded its threshold will blink at one second intervals on the graphic display. The blinking pressure will continue for the rest of the ignition cycle or until an EVIC button is pressed. If the display is removed without correcting the condition, it will reappear without a chime after 60 seconds to warn the drive of the low/high pressure condition.
A non-critical alert will be triggered when low or high pressure threshold has been exceeded in the spare tire. The "SPARE LOW PRESSURE" or "SPARE HIGH PRESSURE" alert will be displayed for 60 seconds during each ignition ON cycle. If the pressure threshold is exceeded while the ignition is OFF, the alert will be delayed 8 - 10 seconds after ignition ON.
NOTE: The spare tire is only monitored when equipped with the 5-Tire TPM System.
System Faults
NOTE: The Remote Tire Pressure Monitors (RTPM) are not internally serviceable. For a Sensor Failure or Low Battery fault, the RTPM must be replaced.
There are four conditions which will cause a Tire Pressure Monitoring System fault to be set. All fault codes are associated with a specific wheel location.
1. If the EVIC detects a non-transmitting Sensor Transmitter in a road wheel for ten consecutive minutes with vehicle speed above 25 mph (40 kph), it will:
a. Store an active fault code.
b. Request a chime.
c. Display "TIRE SENSOR BAD / MISSING".
d. Display a dashed line at the wheel location on the graphic display if the display is activated.
When the EVIC detects:
2. A low pressure sensor battery status.
3. All five sensors transmitting at a shorter than expected interval.
4. No valid pressure sensor ID from the spare tire for 20 consecutive ignition cycles spaced at least one hour apart, it will:
a. Store an active fault code.
b. Request a chime.
c. Display "TIRE SENSOR BAD / MISSING".
Use the DRBIII Input/Output function to further isolate the specific concern.
The DRBIII can be queried to determine the Sensor/Transmitter status:
- "Invalid Pressure" - The Sensor/Transmitter is reporting a negative pressure or a pressure above 434 kPa (63 psi).
- "Low Batt" - The Sensor/Transmitter has reported a low battery status for seven consecutive ignition cycles.
- "Trained" - The Sensor/Transmitter ID code is recognized by the EVIC.
- "Active"- The vehicle is moving at 40 km/h (25 mph) and/or the Sensor/Transmitter is "awake" and transmitting as expected by the EVIC.
Spare Wheel Auto-Locate (5-Tire TPM System Only)
If the spare tire is mounted on the vehicle, the EVIC will detect the move and determine from the sensor transmit intervals, which wheels are mounted and which one is now the spare. The spare tire sensor/transmitter transmits once per hour. The sensor/transmitters in the mounted wheels transmit once per minute when the vehicle is' moving at 40 km/h (25 mph).
Remove Magnet From Spare (5-Tire TPM System Only)
A magnet is used to initiate a sensor ID transmission. In the EVIC training procedure, the spare wheel is the last in the sequence. If the magnet is left on the wheel, the sensor/transmitter will continue its ID transmission. If the EVIC detects 20 transmissions from the spare wheel in 60 seconds and the vehicle speed is above 40 km/h (25 mph), it will:
- request a chime.
- display "REMOVE MAGNET FROM SPARE" for 60 seconds per ignition-ON cycle. 1.6 Tire Pressure Unavailable
The EVIC can detect high radio noise interference. When the noise level is too high to distinguish a transmission from a sensor/transmitter, it will:
- display "TIRE PRESSURE UNAVAILABLE" for 5 seconds.
- request a chime
- switch back to previous screen.
Tire Pressure Now Available
If the "TIRE PRESSURE UNAVAILABLE" message was displayed because of radio noise interference, the EVIC will:
- display "TIRE PRESSURE NOW AVAILABLE" for 5 seconds.
- request a chime when the noise level no longer interferes with sensor/transmitter transmissions.
Diagnosing And Clearing System Faults
All Tire Pressure Monitoring System Faults are specific to one location. If a "LOW BATTERY' fault is detected, the "TIRE SENSOR BAD / MISSING" message will be displayed. The appropriate sensor/transmitter can then be replaced.
If a single sensor/transmitter cannot be detected by the EVIC, replace that sensor transmitter. If none of the sensors/transmitters can be detected, refer to symptoms in the EVIC section.
System Test
A test of the Tire Pressure Monitoring System can be initiated in the EVIC. The test sequence is as follows:
1. Scroll to the blank display by pressing the STEP button.
2. Press and hold the RESET button for five seconds.
3. The EVIC will emit a beep to indicate the start of the test.
4. The EVIC will clear the sensor signal counters
5. The vehicle icon will be displayed with transmission counters at each comer. (Same display as for pressures but with counters in place of pressures.)
6. Drive the vehicle at speeds above 40 km/h (25 mph) for 10 minutes.
7. The counters will increase by one each time a sensor signal is received by the EVIC (approximately 1/min from each wheel except the spare).
8. The test will continue until any EVIC button is pressed or until the ignition is cycled to OFF.