So, earlier this year I replaced my alternator and diode from the Z store ( 240z Alternator Upgrade with internal voltage regulator)

I have been driving it on and off all summer and fall. Today I took the car for a drive in a light rain, with the wipers and headlights on and made a couple stops in town, started no issues. Drove home about 20 miles and got to my driveway and turned off the car so I could put it in the garage, but left the lights on. Went inside and grabbed a set of keys, came out and the car would not start. I had to jump it..... I did noticed the blinkers were slow when I was coming home,,,,,,, The AGM battery tested fine a few months ago and it's "sits" with a trickle charger on it....... Thinking the Alternator might of went? Battery went bad ( it is 3 years old)? Before I dive into it, I thought I would ask for advice..... It seems odd that the rebuilt alternator from the z store would have gone bad? Before I pull it and have it tested, has anyone had issues with rebuilt alternators?

Any advice is appreciated.......

Edited Saturday at 06:10 AM2 days by 70z4fun

Everyone on this forum I believe has had issues with rebuilt alternators and starters. Take it to the parts store and have it checked out.

Good opportunity to learn how to use a multimeter. Check voltage at idle and while raising RPM. Some of the conversion plugs from MSA have been known to melt and fail.

You can get a cheap meter for cheap at a place like Harbor Freight.

https://www.harborfreight.com/7-Function-Digital-Multimeter-59434.html

Here's an old thread about a similar problem.

(Edit - man, I wrote a lot of stuff back then.)

Edited Saturday at 06:30 PM1 day by Zed Head

Agree with Yarb on rebuilt alternators. I make the store test them before I buy one. Been burnt before with a bad one, literally. Popped all my fuses as soon as I cranked the car.

If you have a volt meter or can borrow one, check the fully charged battery without the trickle charger. Mine usually reads about 12.5 volts. Then crank the car and see what the alternator is adding, should go up to 13.5-ish. Check the alternator belt to make sure it's good and tight. I always use a broom stick or similar as a pry bar to get mine tight.

Thanks for the replies......

I did let the battery charge overnight, and it is reading 12.8V with the meter. Tested it with my harbor freight battery tester, and it tested at 750 cold cranking amps.

I pulled the Diode plug and tested it with a meter, it looks correct, shorted on the two pins, and diode tested fine on the other two pins. It does look a little melted on the top of the white plastic top...

When I start up the car, and at different revs.......the battery voltage stays constant, so thinking no output on the alternator.

I might yank the alternator out tonight and take it to Auto Zone and have it tested.........IF it's bad, I wonder how Motorsport Auto will deal with the warranty, it there is one.........

So, do you guys go looking for a new alternator or roll the dice with a rebuilt one?

Edited yesterday at 12:12 AM1 day by 70z4fun

1. Put the key in ON without the car running.

2. Check for voltage to ground on the lower pin of the T connector on the back of the alternator (white/black wire). It should be about battery voltage.

If you don't have voltage on that terminal, the alternator won't supply power.

ok, will check that out, since I have already pulled the alternator, took a whole 20minutes........

I guess I can check to see if there is continuity from the battery terminal to the "T" connector?

Is there a fuse inline somewhere? I know there is a fusible link come off the starter..........

Okay, I'm going to assume the battery is disconnected.

1. Put the key in ON.

2. Put your meter on resistance. If there is more than one setting, put it on the lowest setting.

3. Put the positive lead on the black/white wire at the ballast resistor.

4. Put the negative lead on the white/black wire at the T connector. (Yes, you'll probably need some help.

5. Record the reading and report back.

6. Swap the leads and remeasure.

7. Record the reading and report back.

Correct, the battery is disconnected.

Here are the readings, but I did both high and low settings......

With the Positive lead connected to the ballast, here are the readings:

Edited 12 hours ago12 hr by 70z4fun

Here is the reading with the leads switched

Steve won’t get notified on the forum if you don’t use the “@“ before the user name. In this case it’s “@SteveJ”.

Just a heads up when you are replying to a certain member with a message or response.

Edited 12 hours ago12 hr by Yarb