Compass Loses Calibration

[foosh]

Yesterday, I noticed that the compass display on my rear view mirror was frozen in the N direction. I performed the reset/calibration procedure described on p. 111 of the manual, and it worked accurately.

When I left home this morning, it started displaying in the correct position (garage/driveway oriented SW), but before I had time to depart my driveway, it was again frozen in the N position. I performed the reset/calibration procedure again, and it functioned normally on the way to work.

I don't rely on it very much, as I usually leave the map display in the small right-hand window, and it's not a big deal. But I'm curious if there have been similar experiences or does anyone have information on this phenomenon?

[JCtx]

Is your battery well charged??? Every time I've had behavior like that (needles sweeping gauges, trip computer zeroing itself, etc), has been due to a low/defective (dropped cell) battery.

With all the electronic crap running several minutes after turning engine off, if you don't use the car daily and for several miles each cycle, the battery will keep discharging slowly. I charge it every week myself. Good luck.

[foosh]

Originally Posted by elp_jc

Is your battery well charged??? Every time I've had behavior like that (needles sweeping gauges, trip computer zeroing by itself, etc), has been due to a low/defective (dropping a cell) battery.

With all the electronic crap running several minutes after turning engine off, if you don't use the car daily and for several miles each cycle, the battery will keep discharging slowly. I charge it every week myself. Good luck.

Yes, good question and that would explain it, but I've noticed no other electronic anomalies, and I drive the car at least 70 miles daily x 4-5 days a week. It's my commuter car.

I would assume if it's a defective cell, I would have noticed other issues related to low battery power. It could well be a problem with the electronics in the mirror assembly.

[JCtx]

Originally Posted by foosh

I drive the car at least 70 miles daily x 4-5 days a week.

That's definitely enough to keep the battery charged, but don't discount a defective cell. On large batteries, like ours, you might not notice anything wrong with your starter, etc. That was exactly what happened with my Navigator, which was the car I learned from about this behavior.

I'd charge the battery (I always use a Battery Tender Plus) and check it's voltage; it's that simple to rule that out. If it checks out (12.6+ V), I'd definitely blame the mirror then. Good luck.

[foosh]

Yeah, I've experienced plenty of dead cell batteries in the past. I do have the equipment to test the voltage and will rule that out.

I doubt that is the problem however. I haven't lost any of the other memory settings (e.g. radio/nav, etc.) which depend upon electrical power. The car did sit for 10 days with no trickle charger while I was on vacation during the week before Labor Day, and it started right up. It's been driven almost every day since.

Thanks for the input.