Offroad-Express

Hey guys,
I got my Terrano a bit deep in the water a couple of days ago (as in headlights only just above water, under for a moment). Stereo made a sudden loud as fark, "dat-dat-dat-dat-dat" sound, like the speakers were directly wired across AC.
Driving today my battery/alternator light came on, then I think shortly after the oil light came on. Naturally stopped to check the oil level asap. It was fine. When I restarted I noticed these two were dimmer than the other lights that come on when key at start position (like maybe 70% brightness). Revving the engine they get dimmer with more revs (down to maybe 20%)..
Anyone have any idea what could cause this. I'm guessing it's something that's common to both of these dash lights. Haven't metered the battery yet to see if alternator is actually charging. will do in morning.
thanks for any pointers.

Your alternator has died.

Time to get it rebuilt.

Thanks for reply dieselboy. Logical assumption - I remember now alt light can indicate a bad winding or rectifier diode that's gone open circuit.
However seems to have come right, strangely enough.
First off, I realised later it wasn't the oil light, rather the coolant level warning.
When I tested it in morning, revving the engine showed voltage rising, though starting voltage was really low as if it hadn't charged when driving the day before.
I unplugged the large connector on back of alternator, and single inline connector that hangs straight down from alternator, and sprayed them both liberally with WD40. Also topped up the coolant overflow tank, though it was still on/above low.
Plugged in connectors and fired up and noticed immediate improvement - coolant light off, alt light very dim. Within an hour or so of driving it was totally off.
Easiest fix ever...

BTW, The loud 'dat dat dat' sound through the stereo had stopped as soon as I was out of deep water.

Does anyone know if these alternators (vacuum pump one - Hitachi?) are externally regulated?

Don't think they make external reg alts anymore

your probably right, but it seems strange there's so many small wires coming out of the plug at the back. Guess it might relate to the vacuum pump.