So the other night, I'm leaving work and hit the keyless to get in the car. As soon as I turn the ignition, I lose everything electrical...no lights, no ignition, no keyless, nothing.

Called AAA to get a tow home after I tried to jump start the car...AAA guy hits the positive terminal (on a yellow top optima under 1000 miles and only a few months old) and the car fires right up.

Here's where it gets interesting...I notice on the way home that night that when the motor gets over 2000 rpm's that the voltage drops from around 14 to around 12-11v. The lights start to dim and my 'check gauges' light/sign flickers momentarily.

So I get the Optima yellow top replaced...but the car is having the same issues...voltage drops over 2000 rpms. below 2000 rpm's or idle the car runs around 14.v

So I pop in an older alternator I had lying around from before my rebuild. After installation...I notice the car is now running 11.4v at all RPM ranges. I used a multimeter to make sure my gauge cluster wasbt faulty.

Next, I pop in the previous alternator so at least I can around 14 volts and limp the car. After popping in the original alternator, I get the same issue as the old alternator...only about 11.5volts.

So I check the positive cables and terminals on the battery/alternator...look very clean.

I check the ground connector at the battery and on the chassis (passenger side by the fender)...everything looked good.

So I take both alternators to the parts shop for a load test...both pass at around 14.2 volts on the load test...

At this point, I am stumped...any advice would be appreciated before I have to pay someone to fix this.

 

Have you actually traced some of the wiring and checked the connections? Loose pigtails or old ones can be brittle and crumble and they can also effect the actual connection. I was having low voltage issues awhile back, traced my wires and found a few bad spots, replaced them and the pigtails and solved my issue. Hope yours ends up being as simple as mine.

 

Are you talking about the pigtail for the Alternator? or all the (ring) terminals for each positive and negative cable?

 

it sounds like your losing the connection to the battery and when that happens you are running on the alternator which will show 14 volts. wire brush the heck outa the cable ends to the battery, do the same to the wire ends at the power junction box (small red plastic box on the passenger side fenderwell by the battery) and the ground junction next to it. check your grounds, if this is a lt1 then there should be one on the side of the block in front of the starter, one just below the coil on the front of the motor, one under the passenger side motor mount, one under the belt tensioner.

 

Craby...I cleaned the terminals yesterday. My problem is now that I'm not getting anything more than 11.5-12v...which is like the alternator is not even working. Both alternators are good, so I know it's not them.

I'm going to start inspecting the grounds...likely this is the cause. I'm no electrical engineer, but I know that bad grounds can cause lots of issues.

Thanks for telling me all the locations. I forgot there was one under the tensioner...does the tensioner need to be removed???

 

Where are you checking for voltage? Check alternator output right at the alternator (bigger red wire in the back). If the alternator output checks out, and you're reading low at the battery, it's a wiring issue to or from the battery. What's your voltage reading at the alternator?

 

I believe he said around 14.2 volts( Not in the car)

I would suspect your grounds as well (I had the same problem and my car acted possessed at some points), alot of engine deposits, dirt, and grease tend to cover and get between the ground connections and metal and can cause shorts or bad connections

 

Yes, that I know about the store test. My question was if he checked the voltage at the alternator after it was on the engine?
Exciting the voltage regulator while doing a bench test is one thing, but his system may not be doing that correctly.

 

I see, i apologize. Less than 14.2 while hooked to the postive end(on the back of the alt) might signal a bad ground to the battery

 

It could also be that his electrical system isn't telling the voltage regulator to kick in. That would mean a bad/broken exciter wire (the other "hot" wire that's on the alternator plug).
Also make sure the ground connection to the alternator is good.