I've done the alternator upgrade with a new CS144(not remanufactured) about 2 years ago(~ 8k miles) along with the big 3 wire upgrade. After the last 2 or 3 car washes(done by hand with a power washer) I'm reading over 18 volts on the scan gauge(also confirmed on the battery while running) for a short period of time. It usually settles down to 14.3-14.7 volts a few miles later when it seems to dry out. I suspect that when I'm washing out the drivers side wheel well, some of the water is hitting the alternator. I confirmed this by covering the alternator with a towel and washing the runner as usual and didn't see any spike in volts afterwards.

Out of the dozens of times I've washed my runner, not once has this happened with the stock alternator and with the CS144 alternator up until now. My question, is this alternator faulty because it's giving me these spikes, or should I be putting gobs of dielectric grease on the connections on the back of the alternator to fix this? I still have the rubber wheel well cover flap in its position with one missing plastic insert so it there is a bigger gap. I don't think this is really the issue and it's not like I point the power washer directly at the alternator when I'm cleaning the wheel well.

Should I chalk this up to being more careful when washing it or should I consider a new alternator?

Normally a voltage spike means there's an issue with the voltage regulator. However, since you said when it dries it's no long an issue, I would just chalk it up to the alternator getting wet internally and it's somehow bypassing the regulator.

Now if it starts doing that every time it rains, I'd replace it. Voltage spikes are no bueno.

Sounds good. We've had some really bad weather including rain and snow, no spikes whatsoever.

Im guessing it was just a random event. You can put some die electric grease on the connecter just to be safe but id imagine most rainy days all cars get pretty wet from the radiator blowing water into the engine.

I have seen 15.5v on my cs144 multiple times but It settles down fast. Just keep and eye on it. I installed a volt meter gauge since I always like to know my battery volts.

15.5 is pretty normal on a fully charged battery in cold conditions.

On these old GM alternators you can short out the regulator and full field it with a paperclip through the back...chances are the water is doing that for you,,it's an old way to test output on a bench...I think you can put a touch of sealant on the back hole that does that...I just can't remember exactly where that spot is to seal up...I can look at one in the garage and see if I can find it.

Snagged this photo from online, can you point out which hole should be sealed?

This is where it is on this GM that I remember from long ago..I really can't recall where it is on the 1344.

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haha i know this problem well. when mine gets wet it like putting out 16 volts... thank god i have a daily...

If you ever install a vital part that is not a TOYOTA part, it is a disaster!

My 4Runner must be a complete disaster area then, I think Trump is going to declare a state of emergency to address it and provide funding. I think 5.7bn should be enough to fix up my 4Runner pretty good.

I've got a scan gauge display sitting on the steering column so it's always there showing the voltage, just got lazy with checking it. When it first happened, the ABS sensor came on. I guess when your volts are over 18 it can trip the ABS light. I first thought I may have somehow hit the ABS sensor on the wheel with a jet of water that may have done something to it to trip the light. I never thought to look at what my voltage was when the ABS light came on. I even looked on the forums to see if somehow you could trip the ABS sensor after washing your car. Since the ABS light went off rather quickly I didn't think much of it. It wasn't until I was on a vacation trip, after washing the runner I had mistakenly left my inverter on that's in the runner and the high voltage warning sound went off. This is when I realized I was running over 18 volts on the alternator is what is throwing the ABS light on. After a few miles the voltage went back to the 14s and the ABS light would disappear.

Sounds like its not uncommon for these type of issues. Thanks for the input.

Feeling more relieved hearing more people having similar issues. Thankfully it only does it when I wash the runner.

Wanted to give an update. I believe I found the problem. Recently I started getting voltage spikes all over the place while driving, figure it's time to get an new alternator. I was going to swap in my original since it was good before I installed the cs-144 upgrade. As I'm taking the alternator out, I unclipped the pigtail I bought that allows plug and play from toyota to the Caddy alternator. Unclipped and dirt was caked all inside with some corrosion on one of the prongs on the Male side pretty bad. Scrapped and cleaned the plug and put everything back together and now I have no spikes for a couple days now. Definitely check the connections before deciding to replace. Will update if the spikes come back.