Adjusting (Calibrating) Pcm Navigation Unit: General: Notes

The PCM navigation unit must be calibrated after maintenance work or commissioning. Calibration is the prerequisite for exact route guidance.

The following components of the PCM navigation unit must be calibrated or initialized:

1. GPS receiver: After an interruption in the power supply (terminal 30), the installed GPS receiver loses its so-called almanac. The almanac stores the satellite orbits and ensures fast location of the individual satellites when the system is started.
2. Distance sensor: The distance sensor transmits the distance travelled to the PCM navigation unit. The distance signal changes if the circumference of the tire changes (e.g. tire change). This modification must be calibrated by the PCM navigation unit afterwards.
   NOTE:

   • The distance sensor must be calibrated after commissioning of the PCM navigation unit or after changing a tire. If a system that has already been calibrated is disconnected from the power supply (terminal 30), the calibration of the distance sensor is retained. 
3. Gyroscope: The gyroscope detects changes in the direction of travel and must be calibrated after commissioning.

The gyroscope shows temperature-dependency. This temperature-dependency is compensated by the system if the "cold" (not calibrated) system is switched on and left to stand for approx. one hour.