Dead in the water, well out of the water.

[gait]

I was very impressed with the small size of the bow wave. An unusual degree of self-discipline. Though I suspect accompanied by a desire to use just a little smidgeon of pressure on the accelerator.

I haven't been quite that deep, but no, dashboard lights have never been other than normal.

There is a large junction box, tucked under the front of the cab, that contains half a dozen very big connectors. The box is normally well sealed. However, it may be wise to open it up and inspect, lest there be water in it, waiting to corrode the very nerves of the vehicle.

It may have been simply low voltage.

 

[Aussie Iron]

Aussie Iron, you are braver than me. The water was a bit deeper on the other end but the photos don't really show it. So I used the one with a little bow wave. When I got out the dash was lit up like a Christmas tree. Every alarm light I had was illuminated. They went out after a few minutes of running on dry land. Out off curiosity, does this happen to everyone at this depth?

If it is a FG639 then no it shouldn't happen. Never ever happened to my FG637 So yes it has gotten water into one of the junction boxes by the sounds of it.
Yes, getting yourself a little bow wave going and staying steady on the accelerator is a good thing.
Most people hit the water to fast. The idea is to enter the water slowly and then apply a little throttle to get the bow wave to the desired size. A non-computerized engine will run totally submerged as long as it can suck clear air and doesn't get water in the oil. A computerized engine "may" have trouble with some sensors.

Water crossing are fairly normal for us,
Dan.

 

[SuperVan]

As promised, here is a picture of the Fuso fording. I added a picture of it out of the water to give perspective. As you can see my dog thought nothing of it but I look a little concerned. I think the gauge gave up the ghost way before the water crossing. Like 150 miles prior to.
We do keep a log of the milage and fuel consumption, which is all we have to go off of right now.
I have looked around, but will wait till sunnier days to really tear into it. So, no I have not figured it out yet. Plus, I am going to put larger tanks on replacing the stock tank. At that point I'll be way deeper into the sending and gauge.

Thanks for the help again.

Nice rig! Just sent you a PM~