LS2 A&A Install Alternator Issues
 

I just finished installing a V3 A&A kit on my C6. Everything is working correctly except my alternator/charging system. The car runs and drives without issue at normal speeds, but as you accelerate more vigorously and the supercharger comes on, the battery voltage gauge increases considerably and causes some erratic dashboard lights. Once you stop accelerating it drops back down to normal ranges 13-14v. It only does this under harder acceleration. Using the standard pulley sizes on the whole system. Anyone have any advice or experience with this? Thank you! :flag:

did you get the secondary drive kit for the A&A, generally this is belt slippage.

Belt slippage would see a drop in voltage with rpm. If you have an OD balancer, it may just be due to spinning the alternator faster.

The balancer is the factory size. Out here in Cali we aren't allowed to use different pulley sizes for smog/CARB purposes :ack:

After some more research and playing around I believe the issue is my alternator failing. A friend had a spare Optima Yellow Top battery I put in just to experiment with while I was cleaning grounds and checking connections. It surprisingly helped prevent the issue, likely due to higher capacity than my old battery, but didn't eliminate it entirely. After a bit of digging, I saw that I replaced the alternator back in 2016 with an ACDelco 25888970 on Amazon. Voltage regulator on my old one went (I'm seeing a pattern here) :rolleyes: I went back to look at the listing also found that it's only the early 110 amp version rather than the 145 found in later years. Think this is also part of my problem, if not making it worse. Between that, a likely failing voltage regulator, and all of my add-on electronics, I'm going to just replace the unit with a quality alternator like a Billet Tech or Powermaster so I don't have to worry about it. If it works I'll post again so if someone in the future has these symptoms I can point them in the right direction.

In the mean time, if anyone has any other suggestions please let me know. Thank you! :flag:

Diagnostic Test: Does your horn work?

If not, check the horn fuse. If the horn fuse is blown, it is not sending a voltage ref signal to the alternator. You will need to find the short to ground which is probably the wires going to the horn. Really bad design on the wires coming out of horn btw and with messing with it during the install wires may have rubbed thru. On my car the power wire on the horn rubbed through to horn body. You can remove the horn relay until you get the short fixed. Then replace horn fuse. Still don't understand why gm put the alternator ref voltage and horn on same circuit as it gives you no clue that the fuse has blown.

Hope this helps.

DJ

Hmm...my horn does work. I did read about that being an issue on some other threads. I pulled the fuse and inspected it. Seems fine, but I didn't check the relay. Could be something intermittent going on there. I'll check that out. Thanks for the info! :thumbs:

pull the alternator have it tested.

doh I didn't see that he was going up in voltage, I somehow read that as going down in voltage.

Why pull it ? The autoparts store or any shop can hook it up and check it right in the vehicle. Then they will check if any battery cells are not functioning . BTW, those Optima batteries are now made in Mexico and the quality has gone down hill while the prices have risen, they are not the high quality batteries that they used to be

Because he will have the same issue I have and melt down some things, my alternator regulator went and I had a similar issue.

Just to update for anyone browsing for the same problem in the future, I fixed my problem. It was an intermittent voltage regulator on my alternator. Interestingly, it was not when the BAP came on, it was when the BAP and the radiator fan are on at the same time. Basically at the highest electric demand. So ECM demands max voltage, alternator is weak from engine heat, heavy electrical draw, voltmeter "max's" and fails causing some high voltage warnings and erratic dashboard. Done and Done. Just replaced the alternator and cleaned the connections. I could've just replaced the voltage regulator, but my car has a lot extra electronics anyways so I went with a higher amp Billet Tech. Hope this helps someone in the future! :flag: