Thanks, I'll pull it out and remove the bottom cover (I assume there are no tricks to getting that cover off?). Never thought of looking at that while it was out and I was swapping drives.

I can't imagine how any water would get into there considering how dry it is here year round (about 9" of rain per year average) and that the car stays in the garage when it's raining. Humidity is typically very low here too, so it doesn't seem like condensation should be a problem. But as I had said - it does seem like an electrical connection issue, so maybe something has corroded a connection or 2 somewhere.

Here are some pictures. Mounting location and beneath it look clean - no spots. PCB looks totally clean. The one strange thing is the oxidation or calcium build up, or something else on the outside of the bottom cover. This is where the mounting bracket contacts the cover. Where the metal is cut out of the bracket, there isn't oxidation. Maybe this is from slight periodic condensation over the course of 6 years. At any rate it doesn't appear to have gotten inside.

But a single bad/loose solder joint could probably be the cause of the outages and have nothing to do with water. So far, it hasn't happened often enough to be worth spending serious money to repair or replace it. Maybe next time I'll try dissecting further to look for something loose or broken. Any other advice?

btw, there are 2 external connectors (plus the GPS antenna connector). One connector only has 2 wires. What is their function?

Thanks very much.

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Function of external connectors:

Power
Ground
Video out RGB (3 wires+ shield)
Audio out analog (2 wires)
Ibus
Wheel pulse
Reverse signal

Your lid shows signs of corrosion (white stains) on outside and inside of lid
The case shows also corrosion on the inside (RHS of photo)

Your photo of the PCB is not a new good photo, try again from right above the board (not at an angle)

Sorry about the picture - flash makes it difficult to take a direct picture. Maybe this one is better, but it's early and cloudy now and not real bright outside. (Dark areas are reflection of tree overhead.) If there's something in particular you're looking for I can try from another angle.

I need to figure out if this is a continuing water leak problem occurring when I wash the car (should be easy to figure this out) or if it probably occurred prior to my buying the car 3 years ago. Or if there's a condensation issue.

Thanks.

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This PCB is not damaged. Whatever moisture was in there has long since dried up.

As KiwiJochen pointed out already, the white residues on the housing are signs that your part was repeatedly in contact with quite a bit of water in the past.

Best of luck in finding the point of water entry.

Thanks. I'll wash the car this weekend and put enough paper towels in that area of the trunk to determine whether there is a leak now. If not, maybe the previous owner had an "accident" with the trunk open.

I'm still wondering if just a little condensation, repeated over 6 years, could cause this appearance. How many owners have actually looked at their nav unit covers to see if they have a similar issue?

Just a note of thanks to Autotronic! I was aware that water had entered the vehicle but Autotronic was able to really pinpoint that my '02 X5 has some serious issues with corrosion and helped sort out my MK IV.

Just to conclude my problems from water getting in to the GPS unit:

- GPS stopped working, and would occasionally come on again from time-to-time, eventually just stopped working completely
- Appeared no power was getting to the GPS unless the eject button was depressed in which case it would read the CD

Fix:

- I sent my MKIV to Autotronic and discovered corrosion resulted in the strange GPS behaviour. I will have to get Autotronic to describe the fix as it was quite complicated and as he noted in a previous post may not be salvagable.

Note that the symptons are similar to the requirement of re-flashing the memory so both are possible causes if your MKIV behaves like this.

As far as the water getting in. I have checked out xoutpost and I will be getting a torch while my mate waters it from the outside. I have heard that it can enter from a blocked moonroof drain (not in my case), tail light seals, the bumper area (there seems to be a standard fix for this) and the window. I'll post updates on the water leak thread that I have seen on xoutpost ... hopefully I am successful.

Thanks again Autotronic!

When you post your conclusions, would you post a picture of the installation? I'm not familiar with the X5, especially with the angles that the water would have to take to get to the nav unit. Thanks.

Well with the benefit of some nice sunlight and a magnifying glass, it looks like the water came in through the top vent holes, not from the bottom. Picture shows thin black square around a single 220 ohm resistor and around a pair of 472 ohm resistors and a capacitor (?). At least those look like the values printed on them.

This is what is apparent without lifting the drive, but it's the obvious location, being directly under the vent holes. Really just looks like a few drops of water, which caused some obvious corrosion.

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