Self - Diagnostic Test

A self-diagnostic test is used to determine that the EOM is operating properly electrically. Initiate the self-diagnostic test as follows:

1. With the ignition switch in the Off position, simultaneously depress and hold the STEP and RESET buttons while rotating the ignition switch to the Run/On position.
2. Continue to hold both buttons depressed until the EOM enters the display segment test. In this test, all of the Vacuum Fluorescent Display (VFD) segments are lighted while the EOM performs the following checks:
   • Non-Volatile Memory Status (NVM)
   • RAM Status
   • ROM Status
   • ASIC Communication Status
   • Compass Status
   • DC Status
   • CAN Data Bus Communications Status
   NOTE: If module is equipped with the Universal Transmitter, the module also checks "Universal Transmitter Communication Test Status"
3. Following completion of these tests, the compass mini-trip computer will display one of two messages: "FAIL" or "PASS." Press RESET or STEP to exit and enter normal mode. Respond to these test results as follows:
   • If no test result message is displayed, but compass mini-trip computer operation is still improper, the use of a scan tool and the proper Diagnostic Procedures Information are required for further diagnosis.
   • If the "FAIL" message is displayed, the EOM is inoperative and must be replaced.
   • If the "PASS" message is displayed, the EOM is OK, no faults are present.
   • If any VFD segment does not light during the display segment test, the EOM is inoperative and must be replaced.
4. If the first seven tests pass, the compass mini-trip computer shall verify that all the required CAN bus messages are present on the CAN bus. If all required messages are present on the CAN bus, the EOM will automatically return to normal operation after sixty seconds. The EOM can also be returned to normal operation any time during the test by pressing the STEP, CT, RESET or US/M buttons. The required CAN bus messages are:
   • Dimming message
   • VIN (Vehicle Identification Number)
   • Vehicle Speed message
   • Ignition On Time
   • Odometer
   • Trip Odometer
   • Vehicle Configuration (Model Year, Country and Vehicle Platform)
   • Fuel Economy
   • Distance To Empty
   • Ambient Air Temperature message
   NOTE: Pressing the STEP or RESET switches during any portion of the testing procedure will cause the compass mini-trip computer to exit diagnostics and return to compass/temperature mode.
   NOTE: If the compass functions, but accuracy is suspect, it may be necessary to perform a variation adjustment. This procedure allows the compass unit to accommodate variations in the earth's magnetic field strength, based on geographic location.
   NOTE: If the compass reading has blanked out, and only "CAL" appears in the display, demagnetizing may be necessary to remove excessive residual magnetic fields from the vehicle. Check for stored Diagnostic Trouble Codes (DTCs) and follow the proper Diagnostic Procedures as needed.