Alternator problems, low voltage - 2000 GT

[Nghtrdr]

Hi all
Need some help diagnosing an alternator ploblem I seem to have.
I had to replace my altinator as it was on the way out. So decided to upgrade and had a new 160amp unit made. It didn't produce anything over 13.5v even above 2000rpm. The shop did a few tests in the vehicle and decided to make another one. The replacement would make 13.3v. Again even above 2000rpm. The decision was made to get away from the 3 phase alt altogether and go denso 6phase. The hope was the denso uses a completely different regulator and is a much better alt all around. Well installed it yesterday and guess what, it only makes the same 13.5v as the previous two. These are not rebuilds, these are brand new alts.
Testing has shown its not a ground or power wire issue. They were jumped from the alt to the batt with no change. This eliminates the cables. The sense/trigger wires were tested for proper power on the harness and all seems well. I am completely stumped with this issue. Three brand new alts, 1 totally different, can't be bad.

Any ideas would be very helpful before I go out of my mind. Lol


Thanks
Dan

[Ponyryd]

Have you tried a different battery?

[ZR]

Agreed on battery.
What are you measuring voltage with?

[Nghtrdr]

Batt has been swapped. Mine is in perfect condition and at rest is 12.7v
Snap on test equipment was used to load the alt at the shop that made the alts.
I've personally used my sct tuner to monitor as well as a fluke volt/amp, ac/dc volt meter

[RedSN]

13.5V
How many volts are you aiming for? Pardon my ignorance, but isn't 13+ volts a healthy alternator?

[ZR]

When running have you checked..........
-output voltage at the alternator itself using it's case as a ground source then using battery as a ground source?
- hooked an aux ground lead from alt case to battery?
- checked small wire inputs for voltage when running?
- bench tested alt output?
- does alternator light work?
- run battery low to see if alt voltage rises?
- running at say 2000 rpm, turn on headlights and blower fan, what does voltage do?

Your below optimum but it's not horrible either.

[WidowrRacing]

I recently replaced the stock alternator on my 88GT...I figured it was well passed due and would be a great upgrade.

After being replaced with a new 130 amp from LMR with it's own 4 gauge power fusible wire. I now have the light on the dash and it charges at 13.3.
I even used the stock alternator pulley it came with and not the under drive alternator pulley I installed years ago.

I find it strange the dash light appears now after the upgrade.
The battery is also fairly new.

I'm going to remove the alternator and have it checked over by an alternator shop.

[ZR]

3G style alt?

[WidowrRacing]

In the LMR SVE ad it states:
This alternator is from the internally regulated 3G series.

comes with a **Limited Lifetime Warranty**

Item #SVE-17046K2

[Ponyryd]

Batt has been swapped. Mine is in perfect condition and at rest is 12.7v
Snap on test equipment was used to load the alt at the shop that made the alts.
I've personally used my sct tuner to monitor as well as a fluke volt/amp, ac/dc volt meter

12.7 is over voltage. Is that with a surface charge? Could have a bad cell there.