Hey guys.

Wasn't sure where to put this, but since it's an LS1 alternator, as well as LS wiring, figured this would be the place.

Last night, while driving home in an absolutely TORRENTIAL downpour, I ran through a really deep puddle (read: lake) a little faster than I intended due to almost no visibility. As soon as I got out of it, I noticed all of my lights were brighter, and my wipers were going at crazy high speeds. Glanced down, and my volt gauge was sitting at 18 volts !!!!! I was still about 2 miles from home, and had no choice but to drive it. Once I got it home, I checked voltage at the battery and it was indeed at 18 volts! Shut it down ASAP and checked again, and the battery was trickling down past 12.9v.

So. Here's what I've done so far, besides read anything I could find on this. After about 2 hours, I took the alt off, and ran it up to my local parts store to test it and it passed all tests. I had them run it 3 times. Max voltage was at 15.01. I didn't reinstall it last night, but just in case I wanted to get any and all input on it. One thing of note: when I unplugged the main connector for the alt as I was removing it, I found some water inside it, even with the weatherpack seal. I was thinking maybe that had something to do with it, but I'll know for sure once I reinstall it tonight.

I'll keep this updated as I noticed most threads that have had a similar problem (very few), never really finished or said how they fixed it.

-B

 

Get a new alt or new voltage regulator for it.Or time to upgrade to a truck alt if you need a higher amperage factory alt.

 

Funny thing is, I had a truck alt when I first bought my engine, but I sold it off to help fund the swap lol. I got the LS1 alt for ease of installation in factory location.

Is there a way I can test the regulator underload without the possibility of frying the rest of the electronics? The tester said it passed, but I'm not so sure. Only way I know of, right now, is to reinstall it and start it up to see. I'm also going to check my connections at my junction box, grounds, and at the starter just in case.

 

^^ regulator was probably wet and not functional. If it tested fine on a bench test it might have made it ok when it dried out. Wouldn't hurt to replace the regulator while it is out though.

 

Well, it only took me about 15 minutes to remove the alt, so I'll throw it back in and see what happens. I suspect the water in the connector was part of the problem, if not the entire problem.

If it comes down to it, I'll see about replacing it. It's a reman alt, and I may be able to sneak it back in under warranty lol.

 

I had a similar issue once in my 'bird

I pulled the plug and noticed water in the connector. Blew that out with some compressed air, then looked at the plug and noticed one spot was missing the rubber plug, so I filled it with some silicon and haven't had a problem since.

and I drive my firebird in all sorts of weather. I built it to be driven, not to be a garage queen.

 

It's the only explanation I've got at this point. Checked every ground, and every main wire. Everything ohmed out at less than an ohm, some less than .5. Everything else was tight and clean, so I slapped in some dielectric grease, put the connector back in, hooked it all back up and reinstalled the alt. Fired it up and sitting at 14.6 volts. Drove it around last night, and it was consistent at around that.

So, I guess false alarm? I'm going to be watching it closely.

 

I'm willing to bet money on it being the water in the plug.

Make certain the plug has no holes in it like mine did (I think it had two originally, but only needed one) and if it does, seal them off. I haven't had an issue with mine in 7 yrs or so.

 

I'm certain you are correct. Now that I've done some testing, I'll unplug it and seal the connector off. The grease should definitely help with that as well.

 

The voltage regulator is responsible for regulating voltage across the alternator to preset levels. Any resistance (voltage drop) in the charging circuit can only reduce the system voltage, not increase it.

The plug has multiple terminals. The L (lamp) terminal and F (field) terminal are side by side. The L terminal always has voltage when alternator is running. The F terminal is not used, but if it were used then it controls the duty cycle of the field coil... and charging voltage. I suppose it might be possible that water might allow a short between the L and F terminal so that the F terminal goes 100% duty cycle and charging voltage maxes out at 18V. I would put my money on a failing regulator though.

I would replace the regulator, but if you choose to monitor things then keep your eye on the voltage constantly. 18V causes severe overcharge of batteries. That will boil out the water and run the battery dry (ruin it). Worst case scenario is the battery has an internal short and a spark forms in the air pocket left by the missing water.... only it's not an air pocket, it is a hydrogen pocket and the battery turns into a small bomb.

 

I wanted to be sure as I've read through other people's threads where they found similar issues that caused the same problem.

My harness was built by Pocket, and it's a 1 wire setup for the alt. The other 3 pins do not have any terminals contacting them, so water getting in there and causing it to freak out is entirely plausible at this point. Plus, it's a brand new alternator, and doesn't even have 2k miles on it.

I usually watch my gauges like a hawk anyway, so if I see anything that looks like a return to 18 volts, that alternator is history.

Edit: Also, I'm running an Optima Red Top and it didn't even get hot, thankfully. Deep cycle for the win! lol