My car drives and generally behaves fine, but exhibits two strange symptoms:

1. After starting the car and releasing the brake for the first time, voltage drops significantly to about 12 volts for a couple seconds. My understanding is that releasing the brake for the first time cycles the ABS motor pack, but why would this cause such a severe voltage drop?
2. If the idle drops even slightly low (slight enough that the engine itself is running smoothly) the voltage drops to about 12 volts. Otherwise, voltage is healthy at around 14.5 volts.

I thought this might be my voltage regulator, but I understand these are built into the alternator - correct? I replaced my alternator with a new (not reman) unit from NAPA and the problem remains. Could this be a bad ground? PCM problem? Bad hot cable from alternator? Anyone have any other ideas? The battery is brand new, too - a NAPA NASCAR Extreme battery. The charging system seems to work fine, as the car always starts (battery is not discharging)

Thanks all -
M

 

do u have a underdrive pulley set up. sounds pretty much normal. clean the conections at the alt. and the battery. also there is a power juntion box on the passenger side fenderwell, try cleaning the connectors there.

 

I would throw a volt meter directly on the alternator and see if you get the same readings. For all you know, your gauge in the dash could be lying to you.

 

Stock pulleys, but I will try cleaning the connections. Thanks for the tip.

Good point, however, when the voltmeter registers a voltage drop I can see the lights dim and the blower motor slow down - so I am fairly certain the voltage is actually dropping.

 

I'll definately be interested to see the resolution on this issue. Not to Hijack the thread, but I'm experiencing a similar issue except that when the voltage drops on mine it's almost always when the alt is under a fairly high load and I take my foot off the gas. And then again once in a while at idle. It's just a momentary drop and then it comes back.
So I'll follow along with you as well as trying whatever comes to mind. If I get a fix your the first one to know :-)

Van

 

try pulling the relay or fuse for the a/c it may be a a/c clutch going out and when it engages it draws lots of amps.

 

Thanks for the tip, but it's not the A/C - it happens even when the A/C is off (mode selector on dash vents only).

 

I wasn't saying to see if the voltage drops, that's the nature of the beast when there's a current draw.
My point was to check what the voltage reading is at the alternator as compared to the dash gauge to see if the rate of voltage drop is the same. And to know if it is dropping as much as the gauge says. If the readings are different, you either have an inaccurate reading gauge, or a wiring issue in the charging system.

 

I cleaned the connectors at the power junction on the passenger side near the battery and the voltage drop is much less than it used to be. The connectors were really corroded. I also cleaned the ground connector right next to it. The starter has more juice too - I can tell b/c it sounds different. Thanks for the advice.

I found that using battery electrolyte on a q-tip is a great way to clean off corrosion - wipes it off with almost no scrubbing. Used di-electric grease to cover it all up afterward.

 

Thank you, thank you, I was tweaking and poking around the engine and didn't see what was lastly identified here. The problem with my 2000 SS MTI modified engine was perfectly pointed out here in that last thread.
- After boosting up the HPs' and sweetening out the look, my car just died after parking yesterday in a up-hill parking lot - noting that beacause with a cluch I likely wouldn't have taken so long and relied on so many passers by to help jump the car.
This happened once before and I left it all to chance with another tech. - MAN! Because of that, leaving the car care to someone that I hardly knew I missed out on updating the "wiring" and wire maintenance, cleaning, verifying connectivity, etc...!

I'm once again hopeful. - The beast is my second love!

Thx again,
- Neil