Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Self-Check Diagnostic
With the ignition ON, the Compass/Temp Mirror can perform a diagnostic self-check by pressing and holding the Zone/Cal button (left reading lamp button) for 20-25 seconds. The internal diagnostics will sequence the following five tests:
- VF segment display - Illuminates the segment patterns one at a time for 1 second each as follows: CAL; ZONE; N; NE; E; SE; S; SW; W; NW; 0 through 9; C°; F°
- CTM memory - ROM Checksum
- CTM memory - RAM
- CTM memory - EEPROM
- Compass Test
During the self-check, if any of the internal tests fail, the Compass/Temp Mirror will display an "F" and the number of the test that failed. If more than one test fails "FO" will be displayed. P-Pass or F-Fail will be displayed until the Zone/Cal button (left reading lamp button) is pressed and released or the ignition is cycled. If all of the tests pass, the Compass/Temp Mirror will display "P". A VF segment that fails to illuminate will not cause the Compass/Temp Mirror to display an "F". If any segment fails to illuminate or the Compass/Temp Mirror displays "F", the Compass/Temp Mirror must be replaced.
To exit self-check diagnostics, press and release the Zone/Cal button or cycle the ignition to return to normal compass/temp operation.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.