RAM 2500 Truck 2WD V8-5.7L VIN D (2004)
COMPASS/TEMPERATURE (C/T) BUTTON
Actuating the Compass/Temperature Button (C/T) will cause the CMTC to display the compass and temperature information. This function will
operate from another traveler display. The CMTC simultaneously displays the compass reading and the outside temperature. Outside temperature
information is received via the PCI bus from the FCM.
The CMTC module internally senses and calculates the compass direction.
TRAVELER DISPLAY FUNCTIONS
Using the STEP button will change the CMTC between modes of operation and display the appropriate information according to data received from
the PCI Bus.
COMPASS OPERATION
Upon ignition on, if the calibration information stored in the CMTC memory is within the normal range, the CMTC will perform in slow Auto-Cal
mode. In slow Auto-Cal mode, the CMTC 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 memory is not within the normal range at ignition on, the CMTC 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 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:
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The ignition switch must be in the On position and the CMTC display must not be blank.
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If the compass/temperature data is not currently being displayed, momentarily press and release the C/T button to display compass/temp
information.
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Press and hold the RESET button until VARIANCE = XX is displayed. The CMTC will display the variance zone stored in memory and the
word VARIANCE.
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Use the STEP button to select the proper variance zone number, 1 through 15.
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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 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 CMTC receives
PC I 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 will enter into the fast-cal mode until calibration is complete.
To enter the compass into Manual Calibration mode, perform the following steps:
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Drive the vehicle to an area away from any large metal objects or overhead power lines.
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Ensure that the proper variance zone is selected. See "Setting Magnetic Zone Variance."
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The ignition switch must be in the On position and the CMTC display must not be blank.
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Press the C/T button to view the Compass/ Temperature display.
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Press and hold the RESET button until CAL is displayed, then release the button.
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Drive slowly, less than 5 MPH (8KPH) in at least 1 complete 360-degree circle.
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CAL will remain illuminated to alert the driver that the compass is in the calibration mode.
