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Home >> Ford Truck >> 1997 >> Expedition 4WD V8-5.4L SOHC VIN L >> Repair and Diagnosis >> Instrument Panel, Gauges and Warning Indicators >> Testing and Inspection >> Component Tests and General Diagnostics >> Overhead Trip Computer System >> Trip Computer Self-Test

Trip Computer Self-Test

1. The Trip Computer Self-Test can be entered by pressing the E/M and MODE switches simultaneously while starting the vehicle. After entering the trip computer self-test release the E/M and MODE switches. Advancing to a desired test is accomplished by pressing the MODE switch. To abort the trip computer self-test, turn the ignition switch to the OFF position. The numeric display will enter into a Read Only Memory (ROM) test mode. The display should indicate RL in the compass display. If the display flashes at any time during the ROM test, replace the overhead trip computer.

NOTE: Vehicle doors must be closed and the engine must be running while in the Trip Computer Self-Test mode to receive accurate data.

2. Press and release the MODE switch to enter the Non-Volatile Memory (NVM) test. The display will indicate NL in the compass display. If the display flashes at any time during the NVM test, replace the overhead trip computer.
3. Press the MODE switch to enter the display test. Press the E/M switch until the display cycles through the illumination of the overhead trip computer. If the display does not illuminate a portion of the display segment, replace the overhead trip computer.

NOTE: The illumination will cycle through a full segment display, OFF, right segment display, left segment display.

4. Press and release the MODE switch to enter the fuel flow input test. When the engine is running, the display will indicate a non-zero variable in the numeric display and FF in the compass display. If a signal is not received, refer to the Symptom Chart. Overhead Trip Computer System
5. Press and release the MODE switch to enter the speed input test. The display will indicate 00 in the numeric display and SP in the compass display with the vehicle not moving. When the vehicle is moving, the display will indicate a variable in the numeric display and SP in the compass display. If a signal is not received, refer to the Symptom Chart. Overhead Trip Computer System
6. Press and release the MODE switch to enter the battery voltage test. The display will show battery voltage in the numeric display and a BL in the compass display. If the signal is not within proper battery voltage specification, check the battery. If the battery voltage is within specification and the proper battery voltage is not indicated on the overhead trip computer, repair circuit 729 (R/W) and/or replace the overhead trip computer.
7. Press and release the MODE switch to enter the fuel level input test. The display will indicate a number other than 00 in the numeric display and FL in the compass display. If the signal is not received, refer to the Symptom Chart. Overhead Trip Computer System
8. Press and release the MODE switch to enter the rheostat input test. The display illumination will vary as the panel dimmer switch is rotated and DL will appear in the compass display. If the signal does not vary, CHECK the panel illumination dimmer system.
9. Press and release the MODE switch to enter the compass verification test. The display will indicate PAS, FAL, or BAD in the numeric display and CP in the compass display. If PAS is displayed, the system is OK. If FAL is displayed replace the compass sensor module. If BAD is displayed, refer to the Symptom Chart. Overhead Trip Computer System
10. Press and release the MODE switch to enter the driver map light switch test. The display will indicate ON or OFF in the numeric display and LD in the compass display. Press and release the driver map light switch. The driver map light will toggle ON and OFF corresponding to the display. If the display and the driver map light correspond accordingly, the system is OK. If the display and the driver map light do not correspond accordingly, CHECK the map light system.

NOTE: Doors must be closed.

11. Press and release the MODE switch to enter the passenger map light switch test. The display will indicate ON or OFF in the numeric display and LP in the compass display. Press and release the passenger map light switch. The passenger map light will toggle ON and OFF corresponding to the display. If the display and the passenger map light correspond accordingly, the system is OK. If the display and the passenger map light do not correspond accordingly, CHECK the map light system.

NOTE: Doors must be closed.

12. Press and release the MODE switch to retrieve the final test date information. The display will indicate a number in the numeric display and F1 in the compass display. Press and release the MODE switch. The display will indicate a number in the numeric display and F2 in the compass display.

NOTE: This test is only used to retrieve information for hotline assistance. This is not to be used for diagnosing the system.

13. Press and release the MODE switch to retrieve the module serial number information. The display will show a number in the numeric display and N1 in the compass display. Press and release the MODE switch. The display will indicate a number in the numeric display and N2 in the compass display. Press and release the MODE switch. The display will indicate a number in the numeric display and N3 in the compass display.

NOTE: This test is only used to retrieve information for hotline assistance. This is not to be used for diagnosing the system.

14. Repeat the Trip Computer Self-Test as necessary.

NOTE: Pressing the MODE switch will restart the Trip Computer Self-Test.

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