Truck will now no longer start without a jump, but all other electronics work

You just said the same thing I did, but said I’m incorrect?

 

Bumping to $18.

 

Damn son, we in a tight spot!

 

I know!! It's getting real!

 

I'm betting on loose battery cables as the culprit.

We already know there was a "loose ground wire" but we don't know the cause or if it was the battery end that was loose or the other end where the ground attaches to the frame or engine block.

 

You said its NOT your alternator...read what you posted

 

OEM Battery is crap. I had mine replaced when the truck had less than 10k miles.

 

This is not correct at all. If the diodes go bad you have NO DC voltage. Everything connected to the truck runs on DC. All computer modules are DC. IF the diodes short out you could get a high AC voltage and begin blowing stuff up. But usually the battery will handle the surge temporarily and throw a warning light.

I have seen a couple battery's explode from a shorted diode and high AC voltage being supplied from the alternator. These were older vehicles. I imagine these newer Tacoma's would shut down before that could happen.

 

You are making the assumption that all of the diodes failed completely, which certainly happens. It's also common that one or two diodes get weak, or fail resulting in an AC signal superimposed on top of the DC. Higher end alternator testers check the alternator waveform for this exact type of failure (too much leakage AC). Batteries will smooth out the ripple substantially, which is what allows the vehicle to still run. This will destroy a battery pretty quickly if the alternator is not replaced.

When I used to work in a shop, this type of failure was fairly common when customers would come in with no starts and had already tried a new battery.

 

A lot of auto parts stores will hook up a load tester to your battery for free.

If you're unsure about the alternator, hook up a voltmeter to the system; there's any number of gadgets that include one or you can set up a dedicated gauge. I have a clinometer that plugs into the "12V" poser socket that reads out the system voltage as well, or there are a bunch of different options that'll read voltage along with adding USB power ports and fit into OEM switch or power socket knockout holes.

If you're reading over 13V with the engine running the alternator works fine, if you're reading the same with the engine on vs engine off, then there's an issue with the charging system that could include a bad alternator.

OBD2 monitors or bluetooth dongles with a phone app can also be used to monitor system voltage as well.

 

Better tip. He should buy a f'ing boat if he wants to go in water.

 

Nobody suspecting water in the engine ? It’s submerged no snorkel .

 

A little bit of water should have cleared out the tailpipe by now. A lot of water would have hydrolocked the engine and caused a much bigger and more permanent problem.

Probbably not a bad idea to change out the oil in the crankcase and diffs to be safe though.

 

All it needs is a pro grille

 

And it isn’t the alternator (if the OP was accurate in his post). If it was the truck wouldn’t run once the jumper cables were removed. Read what you said. If the alternator is NOT producing electricity, the truck dies once the battery is dead. The battery was dead, which it why it needed the jump. So tell me, if the battery is dead how is the truck running if the alternator is not producing electricity?

 

My 2017 did the same thing without getting wet all the electronics worked but it would not turn over. Replaced battery and good to go. By the way no new Toyota battery for me I bought one from Sam’s club.

 

This is prob all a repeat.

1. Check for loose battery connections
2. Check for corrosion on the battery terminals and clean
3. Replace the battery, stock are junk

 

So the battery was on its last leg, but not the problem. I just took everyone's advice and replaced it regardless. I'm now positive it's the starter after doing more research. A single click after the start with no crank is the starter. The reason I got a few uses out of it is that the starter dies slowly after getting submerged, and if you jump it at the same time you have a better chance of getting it started. This would also explain why in my first post I noticed a slower start. I got a new OEM one for $130 and I'm replacing it later this week.

 

It was the starter