bad alternator or pcm?

MysticMac

MysticMac

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2000 ls v8.. driving down the road and the check advance track showed up and the car shut off.

I threw in my new battery which was showing 12.55 on the meter in and it started up fine and about 2 minutes later check advance track showed back up then car died... i tested the new battery and it was under 9.30 .... would this be a bad alternator ?
 
MysticMac said:
2000 ls v8.. driving down the road and the check advance track showed up and the car shut off.

I threw in my new battery which was showing 12.55 on the meter in and it started up fine and about 2 minutes later check advance track showed back up then car died... i tested the new battery and it was under 9.30 .... would this be a bad alternator ?
Click to expand...


What's the voltage while the car is running? Should be ~14.5 if the alternator is good.
 
should i have someone testing volts while i start the car or does it matter? can i just test the battery voltage my self with the car running?
 
I was waiting at a light to make a left turn with my signal on and a message came up that said something like "check rear left signal" it was beeping every second until i turned it off.
A couple mins went by and another message came up that said "check rear right signal".
Then the ABS, traction control light came on and a message popped up said something about advancetrac.
The car felt like it was losing power and stalling when I hit the gas. I pulled over and turned the car off, waited a bit. Tried to start it again and all the cluster lights went on and needles started going crazy and the alarm sounded.

Came back to car about 2 hours later and it started. Was able to get it home which was only about a min away. Still felt like it was losing power when I hit the gas, so i just coasted.
Swapped my battery with Mystics and it fired up fine, all dash icons went off and everything looked normal.
Drove down the street and same thing happened. Car lost all power and battery died.
I charged my battery up and put it in. Showed 12.60 on the DMM with car off. Started car and reading was at about 12.19 with engine running.
After about 3 mins with the car idling, volts was at 11.96 and dropping.
 
Definitely an alternator. These cars go nuts on low power, and the gauge sweep you mentioned is the cluster "resetting" (probably wrong terminology there) after a conplete loss of power.

I can't say what brands are good/bad for alternators, but I am curious as well. If it were me, I'd just read reviews on each one. I've replaced a few alts (not on LS'es) before with Autozone cheapies and had no issues.
 
There are many alternator threads on here, including some I started.
I tried a DB unit a few years ago, sent it back. Almost no output at idle.
I've had OK luck with Napa units, plus homebuilt ones with a regulator from alternatorparts.com. It's still a little hit and miss though and sometimes sags/surges at idle.

As Joe said, the safest bet is a genuine, new if you can find it, Motorcraft.

In short, Gen 1 uses an unusual PCM control method that isn't well supported by aftermarket regulators.
 
joegr said:
Yes, don't.

With gen II, you can use almost any alternator. With a 1st gen like yours, hardly anything but Motorcraft works.
Click to expand...

I called the dealership today for a quote and the parts guy said $213 for a Motorcraft +$35 sur fee and I have to give them my old one when done. He said it will be about 5 days to get here.
I have the sport model, is it the same amperage as the standard v8 110a?
 
Is that really the best price in Canada? Motorcraft Alternators are half that much on rockauto here.
 
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