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Home >> Dodge and Ram >> 2004 >> Caravan L4-2.4L VIN B >> Repair and Diagnosis >> Instrument Panel, Gauges and Warning Indicators >> Driver/Vehicle Information Display >> Description and Operation >> Overhead Console >> Tire Pressure Monitoring System (TPM)

Tire Pressure Monitoring System (TPM)

TIRE PRESSURE MONITORING SYSTEM (TPM)
If equipped with the Tire Pressure Monitoring System (TPM), each of the vehicles four wheels will have a valve stem with a pressure sensor and radio transmitter built in. Signals from the tire pressure Sensor/Transmitters are received and interpreted by the Electronic Vehicle Information Center (EVIC).

A Sensor/Transmitter in a mounted wheel will broadcast its detected pressure once per minute when the vehicle is moving faster than 20 mph (32 km/h). Each Sensor/Transmitter's broadcast is uniquely coded so that the EVIC can determine the location.

Training The EVIC
The EVIC can be trained to recognize the source locations of the Sensor/Transmitter signals. The training procedure is given below:
1. From the Programmable Features List select "RETRAIN TIRE SENSORS Y/N" using the EVIC MENU button.

Use the STEP button to select and the MENU button to confirm "YES". The EVIC will initiate the following procedure:

2. A display will prompt the user to: "TRAIN DRIVER FRONT SENSOR". At this point the user must set the left front tire Sensor/Transmitter to learn mode by positioning a magnet (Relearn Magnet special tool 8821) over the valve stem for at least 5 seconds. The Sensor/Transmitter 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: The EVIC will allow 60 seconds from the first train request display to the receipt of a unique learn ID message from the first Sensor/Transmitter and 30 seconds for each succeeding wheel. If either of these timers expires, the EVIC will abort the training procedure and revert to previous settings. The EVIC will not store one ID for multiple locations.
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, and Left Rear).

NOTE:
1. If one or all Sensor/Transmitters cannot be trained, move vehicle to avoid radio frequency interference.
2. If one Sensor/Transmitter still cannot be trained, replace it and retry.
3. If all Sensor/Transmitters still fail to train, replace the EVIC.
4. Once all tires are successfully learned, 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" until another button is pressed and then display "RE-TRAIN TIRE SENSORS? NO". Sensor/transmitter replacement or tire rotation will require retraining of the EVIC.





Pressure Thresholds
The EVIC will monitor the tire pressure signals from the tire Sensor/Transmitters and determine if any tire has gone below the low pressure threshold or exceeded the high pressure threshold. Refer to the table below:

Critical And Non-Critical System Alerts

Critical
A critical alert will be triggered when a tire pressure has gone below or above a set threshold pressure. The EVIC will request a chime and then display "X TIRE(S) LOW PRESSURE" or TIRE(S) HIGH PRESSURE". "x" will be the number of tires reporting low or high pressure. The message will display for the duration of the current 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 300 seconds to warn the driver of the low or high-pressure condition.

Non-Critical
A non-critical alert with no chime will be triggered when no signal is received from a Sensor/Transmitter or when a Sensor/Transmitter low battery condition is detected. The EVIC will display "SERVICE TIRE PRESS. SYSTEM".

System Faults
There are two conditions that 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 condition, it will:
a. Store an active fault code.
b. Request a chime
c. Display "SERVICE TIRE PRESS. SYSTEM".

1. When the EVIC receives a Low Sensor/Transmitter battery report from a Sensor/Transmitter, it will:
a. Store an active fault code.
b. Request a chime.
c. Display "SERVICE TIRE PRESS. SYSTEM".

Use the DRB III Inputs/Outputs function to further isolate the specific concern. The DRB III can be queried to determine the status and battery condition for each Sensor/Transmitter.

Spare Wheel Auto-Detect
If the spare tire is mounted on the vehicle, the EVIC will:
1. Detect the change after 15 minutes at or above 20 mph (32 km/h).
2. Query driver: "SPARE TIRE IN USE?" Use the MENU button for YES, and the STEP button for NO. For YES, the EVIC will revert to the previous display and wait 5 hours. After 5 hours the EVIC will proceed as in the NO response below.
3. For a NO response, after 15 minutes, the EVIC will display: "ALL 5 TIRES W/VEHICLE? Y" Use the STEP button to select YES or NO, and the MENU button to confirm.

For a "YES" response, the EVIC will display "SERVICE TIRE PRESS. SYSTEM".

For a "NO" response, the EVIC will revert to previous display and display "ALL 5 TIRES WI VEHICLE? Y" every time the ignition is cycled to RUN and the missing tire ID is not received.

Diagnosing And Clearing System Faults
All Tire Pressure Monitoring System Faults are specific to one location. If a no-transmit, "LOW BATTERY", "LOW or HIGH PRESSURE" fault is detected, the location can be determined by the DRB III. The appropriate Sensor/Transmitter can then be replaced or the out-of-specification pressure condition can be corrected.

- If a single Sensor/Transmitter cannot be detected by the EVIC, replace that Sensor/Transmitter.
- If none of the Sensor/Transmitters can be detected, refer to symptoms in the Tire Pressure Monitor section.
- If a BUCKET COUNTER test fails, and one or more Sensor/Transmitters does not transmit, replace the affected Sensor/Transmitter.
- If none of the Sensor/Transmitter causes the BUCKET COUNTER to advance, replace the EVIC.
- If the EVIC displays SERVICE TIRE PRESS. SYSTEM and the DRB III sees no Sensor/Transmitter fault or pressure out of specification;

1. Attempt the Retrain procedure. If the display reoccurs,
2. Replace the EVIC.

System Test
A test of the Tire Pressure Monitoring System can be initiated in the EVIC. The test sequence is as follows:
1. Perform the RETRAIN TIRE SENSORS procedure.
2. Press and hold the RESET and STEP buttons for 5 seconds.
3. The EVIC will display BUCKET COUNTERS.
4. Drive the vehicle at 20 mph (32 km/h) for at least 2 minutes.
5. The counters will increase by one each time a Sensor/Transmitter signal is received by the EVIC.
6. Observe that the COUNTERS register at least 3 receptions for each Sensor/Transmitter.
7. Replace any Sensor/Transmitter that does not meet this specification.

The test will continue until any EVIC button is pressed or until the ignition is cycled to OFF.
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