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Home >> Jeep >> 2002 >> Grand Cherokee 2WD Limited V8-4.7L >> Repair and Diagnosis >> Relays and Modules >> Relays and Modules - Powertrain Management >> Relays and Modules - Computers and Control Systems >> Body Control Module >> Description and Operation >> Body Control System >> Functional Operation >> Part 2 of 3 >> Part 2B

Part 2B

ELECTRONIC VEHICLE INFORMATION CENTER
The Electronic Vehicle Information Center (EVIC) is located in the overhead console. The EVIC supplements the standard vehicle instrumentation. The EVIC uses a Vacuum Fluorescent (VF) display to supply the vehicle operator with a compass reading, outdoor temperature, average fuel economy, distance to empty, instantaneous fuel economy, trip odometer, elapsed ignition on time, distance to service, warning messages, service messages and memory system messages. It also provides an interface to enable and disable vehicle programmable features. If equipped, the EVIC is also available with an integrated Universal Garage Door Opener (UGDO) known as HomeLink. Also if equipped, the EVIC is available with a Tire Pressure Monitoring (TPM) System.

The EVIC function buttons are labeled C/T, RESET, STEP and MENU. The three UGDO buttons are labeled with dots to indicate the channel number.

The BCM supplies most of the information displayed by the EVIC. Display information is received over the PCI bus. The EVIC sends and receives data over the PCI bus, communicating with the BCM, PCM, and the Instrument Cluster. Tire Pressure Monitoring System information is received by the EVIC in the form of radio transmissions. The tire pressure sensors are mounted to the vehicle wheels. For complete information, refer to the Tire Pressure Monitoring System section.

Vehicle Information Display
The EVIC provides the following functions:
- Compass direction
- Outside temperature
- Elapsed ignition on time
- Distance to empty
- Average fuel economy
- Instantaneous fuel economy
- Trip odometer
- Distance to service
- Driver alert messages:
- TURN SIGNAL ON (with vehicle graphic)
- PERFORM SERVICE
- DOOR OPEN (individual or multiple doors, with graphic)
- LIFTGATE OPEN (with graphic)
- LIFTGLASS OPEN (with graphic)
- COOLANT LEVEL LOW (with graphic)
- WASHER FLUID LOW (with graphic)

An audible chime or chimes will accompany any displayed warning messages. Chime requests with an OPEN message are dependent upon vehicle speed.

The EVIC will not display information for any of the screens for which it did not receive the proper PCI bus data. Refer to the symptom list in the Overhead Console section for problems related to the EVIC.

The EVIC receives the following messages from the Body Control Module (BCM):
- Verification of US/Metric status
- VF display dimming brightness and exterior lamp status
- Trip Odometer data
- Elapsed Ignition On Time data
- Fuel Economy (Average and Instantaneous)
- Distance to Empty
- Outside Temperature
- Distance to service
- Driver warning messages

The EVIC transmits the following messages to the BCM:
- Status Request: Beep, Reset, US/M Toggle
- Current Display

The EVIC receives the following message from the PCM:
- Vehicle Speed

Step Button
The STEP Button can be used in one of the following three ways:

1. To sequentially select one of seven displays or blank display in the following order:
- Average Fuel Economy
- Distance to Empty
- Instantaneous Fuel Economy
- Trip Odometer
- Time Elapsed
- Distance to Service Message
- Individual Tire Pressure
- Off (Blank)
2. To set the magnetic variance zone when VARIANCE = X (X = 1 - 15) is indicated in the VF Display.
3. To select the displayed programmable feature setting.

Menu Button
Use the MENU button to sequentially step the EVIC through the programmable features.
Use the MENU button to enter the Tire Pressure Monitoring (TPM) Training Procedure.

Reset Button
The RESET Button has two different functions:
1. To clear the trip functions that may be reset
2. To enter and exit the diagnostic mode

Pressing the RESET button once will clear the trip function that is currently being displayed (except Distance to Service) and the EVIC will send a PCI bus beep request to the BCM. If the RESET button is pressed again within 3 seconds, the EVIC will reset ALL of the trip functions and an additional beep request is sent to the BCM. The trip functions that may be reset are:
- Average Fuel Economy
- Trip Odometer
- Elapsed Time

A reset will only occur if one of the trip functions that may be reset is currently being displayed.

Pressing the RESET button for more than three (3) seconds resets the Distance to Service function while the Distance to Service message is being displayed. The EVIC module will send a beep request to the BCM.

Simultaneously pressing the RESET button and the C/T button while turning the ignition from OFF to ON will enter the EVIC into the self-diagnostic mode.

Compass/Temperature (C/T) Button
Actuating the Compass/Temperature Button (C/T) will cause the EVIC to display the compass and temperature information. This function will operate from another traveler display or from the programmable feature mode.

Traveler Display Functions
Using the STEP button will change the EVIC between modes of operation and display the appropriate information according to data received from the PCI Bus.

Compass/Temperature
The EVIC simultaneously displays the compass reading and the outside temperature. Outside temperature information is received via the PCI bus from the BCM.

The EVIC module internally senses and calculates the compass direction.

Compass Operation
Upon ignition ON, if the calibration information stored in the EVIC memory is within the normal range, the EVIC will perform in slow Auto-Cal mode. In slow Auto-Cal mode, the EVIC continuously compensates for the slowly changing magnetic field of the vehicle. The compass module detects changes in the vehicle magnetism and makes appropriate internal corrections to ensure proper displayed direction.

However, if the calibration information stored in the EVIC memory is not within the normal range at ignition ON, the EVIC will enter fast Auto-Cal. CAL is displayed along with the temperature.

Auto activation of the fast Auto-Cal mode will also occur when the EVIC is subjected to high magnetic field strength levels, which cause all compass readings to be erroneous for a continuous period of five (5) minutes. During fast Auto-Cal, CAL will be displayed along with the temperature.

Fast Auto-Cal can also be performed manually, by pressing and holding the get he RESET button for 10 seconds during the Compass/Temperature display mode.




Setting Magnetic Zone Variance
Variance is the difference between magnetic North and geographic North. For proper compass function, the correct variance zone must be set. Refer to the Zone Variance map for the correct zone. Follow these steps to check or change the variance zone:
- The ignition switch must be in the ON position and the EVIC display must not be blank.
- If the compass/temperature data is not currently being displayed, momentarily press and release the C/T button to display compass/temp information.
- Press and hold the RESET button until VARIANCE = XX is displayed. The EVIC will display the variance zone stored in memory and the word VARIANCE.
- Use the STEP button to select the proper variance zone number, 1 through 15.
- After selecting the proper zone number, momentarily press and release the RESET button. The variance zone is then stored in the memory and the EVIC returns to normal operation.

Compass Calibration
The compass module has 2 types of auto-calibration; slow-cal and fast-cal. Slow-cal ensures that during normal vehicle operation the compass performs auto-calibration functions to keep the compass sensors in their proper operating range. Whenever the ignition is ON and the EVIC receives PCI bus data indicating that engine RPM is greater than zero, auto-calibration is performed continuously.

If the calibration information stored in the compass module memory is not within the normal range after a power-up cycle, the compass will display CAL. The EVIC will enter into the fast-cal mode until calibration is complete.

To enter the compass into Manual Calibration mode, perform the following steps:
- Drive the vehicle to an area away from any large metal objects or overhead power lines.
- Ensure that the proper variance zone is selected. See "Setting Magnetic Zone Variance."
- The ignition switch must be in the ON position and the EVIC display must not be blank.
- Press the C/T button to view the Compass/ Temperature display.
- Press and hold the RESET button until CAL is displayed, then release the button.
- Drive slowly, less than 5 mph (8 km/h) in at least 1 complete 360 degree circle.
- CAL will remain illuminated to alert the driver that the compass is in the calibration mode.
- After calibration is complete, CAL will turn OFF. If the compass appears blank, unable to be calibrated, or the compass displays false indications, the vehicle must be demagnetized. Refer to Compass Demagnetizing Procedure.

Diagnosis and Testing

Self-Check Diagnostics
The EVIC is capable of performing a diagnostic self check on its internal functions. EVIC diagnostics may be performed using a DRB III( or by using the following procedure:
1. With the ignition switch in the OFF position, depress and hold the RESET and the C/T buttons.
2. Turn the ignition switch to the ON position.
3. Continue to hold both buttons until the software versions are displayed, then release the buttons.
4. All of the VFD segments will illuminate for 2-4 seconds. Check for segments that do not illuminate or illuminate all the time.
5. When the self-check is complete the EVIC will display one of the following messages:
- PASS SELF TEST
- FAILED SELF TEST
- NOT RECEIVING J1850 MESSAGE
6. To exit the self-check mode, depress the RESET button or cycle the ignition switch and the EVIC will return to normal operation.

If a Communication fault is displayed, refer to the symptom list. If a FAILED is displayed, the EVIC must be replaced.

Ambient Temperature Sensor
The ambient air temperature is monitored by the BCM and displayed by the EVIC. The BCM receives a hardwire input from the Ambient Temperature Sensor (ATS).

The ATS is a variable resistor that operates on a 5-volt reference signal circuit hardwired from the BCM. The resistance in the ATS changes as the outside temperature rises or falls. The BCM senses the change in reference voltage through the ATS resistor. Based on the resistance of the ATS, the BCM is programmed to correspond to a specific temperature. The BCM stores and filters the ambient temperature data and transmits this data to the EVIC via the PCI Bus. The ATS cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

Ambient Temperature Sensor Fault Codes
The outside temperature function is supported by the ambient temperature sensor (ATS), a signal and ground circuit hardwired to the BCM, and the EVIC display.

If the EVIC display indicates 54 °C (130 °F) or the ATS sense circuit is shorted to ground, the temp display will be 54 °C (130 °F) to indicate a SHORT circuit condition.

If the EVIC display indicates -40 °C (-40 °F) or the ATS sense circuit is open, the temp display will be -40 °C (-40 °F) to indicate an OPEN circuit condition.

If there is an OPEN or SHORT circuit condition, it must be repaired before the EVIC VFD can be tested.

The ATS is supported by the BCM. Ambient Temperature Sensor DTCs will be recorded in the BCM. The ATS can be diagnosed using the following Sensor Test. Test the ATS circuits using the diagnostics in the Body Diagnostic Procedures Manual. If the EVIC passes the self test, and the ATS, the circuits, and PCI bus communications are confirmed to be OK, but the EVIC temperature display is inoperative or incorrect, replace the BCM.

Ambient Temperature Sensor Test
1. Turn the ignition OFF.
2. Disconnect the ATS harness connector.
3. Measure the resistance of the ATS using the following min/max values:

TEMPERATURE RESISTANCE

0 °C (32 °F) 29.33 - 35.99 Kilohms
10 °C (50 °F) 17.99 - 21.81 Kilohms
20 °C (68 °F) 11.37 - 13.61 Kilohms
25 °C (77 °F) 9.12 - 10.86 Kilohms
30 °C (86 °F) 7.37 - 8.75 Kilohms
40 °C (104 °F) 4.90 - 5.75 Kilohms

The sensor resistance should read between these min/max values. If the resistance values are not OK, replace the sensor.

HomeLink Universal Transmitter
If equipped, the HomeLink Universal Transmitter is integrated into the overhead console. For added security it will operate home security systems that use coded signals known generically as Rolling Codes. The overhead console display provides visual feedback to the driver, indicating which HomeLink transmitter channel button is being pressed. The HomeLink can learn and store up to three separate transmitter radio frequency codes to operate garage door openers, security gates, and security lighting. The HomeLink buttons are marked with one, two, or three dots. For complete information, refer to Universal Transmitter in the Owner's Manual.

TIRE PRESSURE MONITORING SYSTEM (TPM)
If equipped with the Tire Pressure Monitoring System (TPM), each of the vehicles five wheels will have a valve stem with an integral pressure sensor and radio transmitter. Radio 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 speed is greater 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.

Training The EVIC
The EVIC can be trained to recognize the source locations of pressure sensor/transmitter signals. Use the following training procedure:

1. Locate "RETRAIN TIRE SENSORS" on the EVIC menu.
2. Press STEP button to select YES and MENU button to confirm.
When this mode is enabled by selecting "YES" the EVIC will initiate the training procedure.

3. The EVIC 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-second timer for learning the first tire location and a 30-second timer between the remaining tires. If any of these timers expire the EVIC will abort the training procedure.
4. 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.
5. Once all 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" until another button is pressed.

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.







Pressure Thresholds
The EVIC will monitor the tire pressure signals from the five tire sensor/transmitters and determine if any tire has gone below the Low Pressure Threshold or raised above the High Pressure Threshold. Refer to the table.

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 tire 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 driver 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.

System Faults

NOTE: The Remote Tire Pressure Monitor Sensors (RTPM) are not internally serviceable. For a Sensor Failure or Low Battery fault, the RTPM must be replaced.

There are four 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 in a road wheel for 10 minutes at a vehicle speed above 40 Km/H (25 MPH), it will:
a. Store an active fault code.
b. Request a chime.
c. Display "SERVICE TIRE PRESS SYSTEM".
d. Display a dashed line at the wheel location on the graphic display if the display is activated.

2. When the EVIC detects:
- A low pressure sensor/transmitter battery status for 7 consecutive ignition cycles,
- Any sensor transmitting at a shorter than expected interval or,
- 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 "SERVICE TIRE PRESS SYSTEM".

Use the DRB III Input/Output function to further isolate the specific concern.

The DRB III 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 the Sensor/Transmitter is "awake" and transmitting as expected by the EVIC.

Spare Wheel Auto-Locate
If the spare tire is mounted on the vehicle, the EVIC will detect the relocation 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
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.

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 to the graphic display and show dashed lines instead of the tire pressure for the wheel(s) affected by the radio interference.

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.
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