Help with a drowned landcruiser

At a guess, sounds like low voltage to computer systems.Computer won't run on low voltages they will shut down..Water in connectors or relays some where shorting voltages .Check battery voltages then starter motor voltage when cranking to start . Then check for battery voltages at the fuse and relay panel under the bonnet.
Its just a process of elimination .but start at the battery end first and work your way through circuits

Gary

I'm reasonably sure that the alternators sit low on these so you may have dirty water / mud in there affecting the charge, try spraying it out with clean water then WD40 and let dry for a while, if not you may be up for a new alternator

Charge the battery fully and see if most of the issues disappear. May just have a dead alternator

Alternators don't like being full of mud, jams the brushes in their holder.

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Some good advice above re alternator and possible cause of issues you're having.
It takes time to track things down after such a day out.Just a a lot of investigative trial and error 76.

Ok, my little input, how much electronics are on this rig ?
It seems to me like there could be some sort of limp mode happening.

With the dash functions going out, it sounds to me like an issue I had once coming home from a desert trip, down one of our SA highway-like tracks, plenty of fine sticky mud.
Long (long) story short, I touched my brake approaching a big wet patch on one road, an immediately lost a lot of functions / power, dash elecs, 4WD status indicators and ability to select, speedo haywire, fuel gauges, OBD2 port gauge functions, very weird.
A wire weighted down had come off the trailer plug, the stop wire, and it shorted on the metal of most likely the mounting point for the plug.

I was very much in limp mode.
So in its wisdom, Ford decided to hook the TCM (transmission control module) up into the Horn / Brake light fuse, and not label it, I might add !!
That gone, it was really upsetting the vehicle functions for the near 1000km or so drive home :/

If only I had cause to use the horn and not find it working, or if I had someone behind me call up and say the brake lights are out, I could have found the 10c fuse blown and got all this back to normal in about 30 seconds.
Instead of no options but for an 880km epic drive home in limp mode !!

Without trying to preach you about the past, maybe educate you a little for the future . . .

Many in the 4WD fraternity just love a bit of mud play, don't they ?

Got to admit the pulse starts going when you see it ahead, the anticipation of what's under the surface (to be checked), and that usually it requires a bit of momentum, fast pedal and steering wheel skill.

But mud (especially fine silty mud, and it's always present) is the enemy of ALL electrical and moving mechanical parts.
It gets in and is very abrasive, wearing down anything that moves in the driveline, suspension etc.

Backs of wheels get coated, balances thrown out until cleaned, brake lines etc can get caked, and if mud dries on them suspension movement has actually broken these on 4WDs in the past.

Radiators, intercoolers, oil coolers etc are affected too, it gets into cooling fins and is very good at blocking airflow, and you know what that can lead to on a drive home.
They really need total removing to clean properly if mud dries in there.

I've always done everything I can to avoid / drive around mud, obviously there are exceptions like not degrading tracks, or testing rig / new tyres, or a driver learning how to drive mud for an inevitable encounter.
But if possible avoid it like the plaque in future, unless you like a lot of hard work and / or $.

All the best with your issues, go check fuses if applicable (do it anyway), and let us all know the issue(s) you discover in the end.

How much of the electrics in the engine compartment went under? If there were any then the cost of repairs could write the vehicle off. Is your insurance cover? Instead of stuffing around getting advice from a forum I'd be taking it to a Toyota agent.

It is obvious the alernator has been underwater.
The brushes will have stuff, glued in with grit and mud.
The cleaning of the vehicle may be nice but a hose into the alternator may clean the brushes and allow contact on the slip rings once more. Unless the alt works, all the symptoms you have, will be experienced.

What the others said - alternator disabled by mud/grit/sh!t in/under the brushes.

My youngest son had that exact issue after dunking his Sierra in some mudhole along the Mundaring powerlines. Tried flushing it and cleaning with all sorts of sprays, nothing worked.Was about to buy a replacement alternator. On my direction (remote control!) he stripped it down and cleaned the brush assembly thoroughly. Problem solved.

Low-mounted alternators are a definite weakness in vehicles otherwise capable of a decent swim.

all you need to do is log into LCOOL
there is a sticky under the on how to clean out the alternator bushes
was put up by a mate of mine years ago after he played in the mud.
cheers
Howard

I saw this happen at mt Dare 78 series into deep muddy water over the bonnet , same thing happened ,electrical problems all over the place , hosed it out completely stayed for a day to let it dry , sprayed it with WD40 ,all good again .

saw them 3 days later , still going well .

It might be just me, but I wouldn't be happy with just a hose out and wd40 of the alt, I'd be spending the time to pull it apart and clean it properly.
This is why I avoid mud and deep water like the plague ....only to be tackled if I have to, as opposed to just having a play !!

If you're going to regularly play in the mud, bite the bullet and install a fully sealed water cooled unit and be done with it.

Regards

The alternator is in the middle of the V of the V8 engine and when submerged the engine holds muddy water and silt for the alternator to try and work in. After submerging it needed to be dryed out to stop the alternator from ingesting mud. The advice is correct you need to get the alternator out and clean it. A big job on the Toyota V8 diesel. Hopefully, lesson learned to keep away rom deep crossings.

Cheers,

Lowan

Another trick is to hose out and if the alternator if still not working just give the side/rear a few gentle taps with a hammer to loosen the brushes. Sometimes a bit of grit gets stuck between the brush and holder holding the brush out. Worked on my mates 76 series. Battery voltage would appear to be your trouble and if the alternator is not working recharge the battery, fix the alternator and all should be good. Good luck with it.

Thanks to all who offered their advice it turned out to be the alternator that was causing tje headaches found roughly the entire of telephone lane in there :) plus about 3 tonne of grass and weeds ;) charged the battery and started right up with no loss of power anymore

Thanks again

Cheers jet

76lifted - Don't forget, that after having been through deep water, there are other areas of the vehicle that can be affected, depending on the depth and temperatures.

Drivetrain components that are at high working temperatures, when plunged into cold water, cool rapidly and develop a vacuum, and can possibly suck water in past seals.
It would be nice to think that all seals are 100% effective - but they aren't.

The gearbox and diff can ingest muddy water this way, particularly if the breathers are blocked, or if the depth of water is higher than the breathers.
Most 4WD's have breather extensions, but even these can go under, develop holes in the hoses, or get pinched.

It's a good idea to check transmission and diff for water ingestion after deep water excursions, and this can be found by oil that appears milky, or severe condensation inside the gearbox or diff housings.
You can buy cheap "borescope inspection" cameras off eBay that are useful for checking inside housings for ingested water.

Front wheel bearings are notorious for developing rust on races or taper rollers after having been in deep water - particularly if the vehicle isn't driven at high speed for a reasonable period afterwards, to warm up the bearings again.

Brake discs also get a bad rap, for getting warped when plunged in deep, cold water, when they are hot.
You only find this out after you have been in deep water, and you go to use the brakes, and get a "pumping" effect back through the brake pedal. The only cure for that is new disc rotors.

To avoid brake disc warping, you need to ensure your brakes are cool before entering deep, cold water.

Cheers, Ron.

Maybe consider hiring a dehumidifier to put in the vehicle, to help dry it out more if water got in the cabin