Compass/Mini-Trip Computer / Electronic Vehicle Information Ctr

COMPASS/MINI-TRIP COMPUTER or ELECTRONIC VEHICLE INFORMATION CENTER
The Compass/Mini-Trip Computer (CMTC) or Electronic Vehicle Information Center (EVIC) is located in the overhead console. The CMTC or EVIC supplements the standard vehicle instrumentation. The CMTC and EVIC use a vacuum fluorescent (VF) display to supply the vehicle operator with a compass heading, outdoor temperature, average fuel economy, distance to empty, instantaneous fuel economy, trip odometer, elapsed ignition on time, distance to service, warning messages, and service messages.

The difference between a CMTC and an EVIC is that only the EVIC provides additional memory and feature programming. The EVIC is capable of displaying memory system messages when the vehicle is equipped with memory systems. The EVIC also provides the interface to enable and disable vehicle programmable features when the vehicle is equipped with certain 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.

Both the CMTC and 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 CMTC/EVIC. Display information, except for the internal compass function, is received over the PCI bus. The CMTC/EVIC sends and receives data over the PCI bus, communicating with the BCM and PCM. 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 in this publication.

VEHICLE INFORMATION DISPLAY
The CMTC/EVIC provides the following functions:
- Compass direction
- Outside temperature
- Elapsed ignition on time
- Distance to empty
- Average 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)
- WASHER FLUID LOW (with graphic)
- RKE FOB BATTERY LOW
- LAMP OUT

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

The CMTC/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 CMTC/EVIC.

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

The CMTC/EVIC receives the following messages from the Powertrain Control Module (PCM):
- Trip Odometer data
- Vehicle Speed

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

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
- Trip Odometer
- Time Elapsed
- Distance to Service Message
- Individual Tire Pressure (When equipped with TPM.)
- 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. (When equipped.)

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 CMTC/EVIC will send a PCI bus beep request to the BCM. If the RESET button is pressed again within 3 seconds, the CMTC/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 CMTC/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 CMTC/EVIC into the self-diagnostic mode.

COMPASS/TEMPERATURE (C/T) BUTTON
Actuating the Compass/Temperature Button (C/T) will cause the CMTC/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 CMTC/ EVIC between modes of operation and display the appropriate information according to data received from the PCI Bus.

Compass/Temperature
The CMTC/EVIC simultaneously displays the compass reading and the outside temperature. Outside temperature information is received via the PCI bus from the PCM.
The CMTC/EVIC module internally senses and calculates the compass direction.

Compass Operation
Upon ignition on, if the calibration information stored in the CMTC/EVIC memory is within the normal range, the CMTC/EVIC will perform in slow Auto-Cal mode. In slow Auto-Cal mode, the CMTC/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 CMTC/EVIC memory is not within the normal range at ignition on, the CMTC/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 CMTC/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 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 CMTC/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 CMTC/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 CMTC/EVIC returns to normal operation.

Compass Calibration
The compass module has 2 types of autocalibration; 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 CMTC/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 CMTC/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 CMTC/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 kph) 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 CMTC/EVIC is capable of performing a diagnostic self check on its internal functions. CMTC/EVIC diagnostics may be performed using a DRBIII 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 CMTC/EVIC will return to normal operation.

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

Ambient Temperature Sensor
The ambient air temperature is monitored by the PCM and displayed by the CMTC/EVIC. The PCM 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 PCM. 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 PCM is programmed to correspond to a specific temperature. The PCM stores and filters the ambient temperature data and transmits this data to the CMTC/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 PCM, and the CMTC/EVIC display.

If the CMTC/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 CMTC/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 CMTC/EVIC VFD can be tested.

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

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 Sensor Resistance

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

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.