QuiGonJon

Hey guys, hope you can help with this one

1991 4runner 4x4 v6 3.0 auto
Went off roading today, went through a small creek. Mostly pretty shallow, went through a bit about 18"- 24" or so, splashed quite a bit but made it through. Right when I got out my dash looked like Christmas with all the lights that came on. My CEL was previously on. Here's all that happened:
A/T OIL TEMP light on, trans is fine
BRAKE light on, E brake disengaged, fluid level good
REAR ANTILOCK light on intermittently
BATTERY light on
CEL turned off, then flashed, then off again for good
Checked under the hood, nothing disconnected as I could see. Battery connections good. Fuse box/connector on pass side of engine compartment wet, mostly from underneath. Alternator looked dry.

Ran fine for a bit till I got back on the road. Started misfiring BAD, losing power, could barely crawl. Turned off, turned over, ran better but started misfing again
Low RPMs were the worst, higher RPMs ran better.

Then I noticed something really weird, in low RPMs trying to get up speed, while misfing I would feel a clunk or bang under my feet or in the firewall, really felt like something was loose and hitting but couldn't see anything. Only happens at low RPMs

Eventually could barely move but still idled, so a bud towed me with a strap most of the way home. Sat in neutral being towed and noticed voltage dropping until eventually truck completely died about 7mi from home.
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While just idling I never felt the clunking/banging

I think I got water damage in the fuse/wiring going to the alternator, killing the alternator, not enough voltage to fire all cyls, battery light, etc. But it doesn't answer everything, like A/T light, clunking, brake light.
Any ideas where I should look or what I broke?
Thanks in advance

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maco35

First check your E.C.M. or E.C.U. (computer) i'm thinking it got wet, next check the oil to see if water got in the crankcase somehow, that's how i hydro locked and killed my engine back in 2011.

QuiGonJon

I'll check the ECU. I don't think there's water in the oil, I checked it immediately and it looked good, didn't notice any moisture
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Today I jumped the truck and it started up and ran good while cables were on, soon as they were off it slowly started misfiring and died. Gonna pull the alternator and have it tested

maco35

The ecu is behind the passenger side kick panel.

QuiGonJon

Tested the alternator, it was fried. New one in and it's all good as new, all lights went off. Didn't think just the alternator could cause all those problems, learned something new. Thanks for your help

MaK92-4RnR

Alternators and distributors on the 3vze are not water proof. They cant even handle direct water on them when washing the motor, either.

scope103

It can't. Something else (lots of things) was going on. Let's just hope that they all dried out and you've got no long-term damage other than the alternator.

Shake rattle n roll

It can , I watched the smoke escape from my alt on my 73 celica alternator.

yep i cookd it welding....

if the headlights were on you couldent shut the car off with the key.....

QuiGonJon

I've driven a few hundred miles since and so far so good, don't think there's any underlying problems. Good to know about the alt being water sensitive, I'll be watchful of that in the future.

RAD4Runner

YUP, that's why for real "Third World" conditions, simple diesels rule; once started they would run even if you disconnect battery and alternator...

RJR

Same is true for piston airplane engines. They have magnetos, carburetors or mechanical fuel injection, and engine driven fuel pumps (or gravity feed for the high wing planes), so you can lose the entire electrical system and the engine just keeps humming along. I know, I've been there. It's a good feeling not to be relying on some microprocessor running Windows CE while you're up in the air.

For real backcountry overlanding, a magneto sparked engine would give an extra boost to reliability. Can't beat simple.

scope103

Magnetos? Meh. They are used on small aircraft for good reason; if the electrical system fails, at least that won't take out the engine. (good luck trying to fly through clouds, or contact the tower, or even land at night at an unattended airport.) But aircraft designers have so little faith in magnetos that they require all engines to have TWO of them. And when they do fail, getting them to work correctly again is a big deal.

Even for backcountry overlanding, I would personally stick with modern engine electronics. YMMV.