Reset by unplugging nav or disconnecting battery

Make sure you have latest software version - try a fresh loading of the OS (use NavCoder, "CodeDefaults" - this wipes the memory and forces a full new OS reload)

If that doesn't fix it then the gyro is faulty.

Replace the gyro (you need to get a new one from SiemensVDO, needs 2 x soldering irons, 2 x people and a hot air gun to replace. Alternatively, purchase a 2nd hand faulty Mk4 nav and use its gyro)


Model | Position | SiemensVDO Code No. | Description
MK3(__) | 7556 | 311232855100 | UNIT GYRO EWTS4M012 SELECTED
MK3(Z8) | 1004 | 311232854940 | GYRO ASSY 90DEG (ONLY 22SY591/23S)
MK4(__) | 7801 | 311230055840 | GYRO EWTS82NM21
MK4(Z8) | 7802 | 311233855730 | PWB ASSY GYRO VERTICAL

You need part 311230055840

Or replace the entire nav :-)