electrical problems have me stumped

[LETZRIDE]

While yes this is with my LS1 a lot of the way the electrical system works is the same for all F-bodies...so here is my situation and hoping someone has some ideas or things I can test:


The car is a 2002 LS1 Camaro

After installing a new set of Spec D tuning ebay headlight to replaced my broken factory ones, I was aiming the headlights on the car with the engine off and boom after about 30 minutes the car is completely dead in an instant - to the point not even the interior lights flip on...ok that's maybe to be expected.

I boost the car and the battery cables smoke a little bit and get hot as hell...weird...car starts and ends up dying at idle about 5-10 minutes later...no biggie, pull it in the driveway and put the trickle cell charger on it. Battery goes from "dead" and zero response from electronics to showing 100% charged in about 10 minutes...weird but whatever ok... cars sits for 2 weeks and still fires up...when driving the volts seem to be dropping into the red area of the gauges.

Sooo.. I grab the voltmeter and I verify after letting the car sit over night - battery shows 12.4 volts across the terminals.

Key on engine running it was showing 13.1-13.3 volts...so I believe the alternator to be junk. Call the scrap yard and pick up a truck alternator as a replacement and pop that in... start the car up and it shows 13.8 volts...after a drive and a retest it shows 13.1-13.3 volts at idle...if you rev the car in neutral I drop to about 11.xx volts above 3,500 rpm. If I enter the highway and go WOT by the time I hit 80mph my check gauges light is on and I am buried in the red on the volt gauge.

So I think maybe it is the exciter wire- pull that plug off this morning and I got 9.78 volts going to that plug with the engine running and it unplugged from the alternator.

So I am stumped...battery shows good, exciter wire I think is good, they tested the alternator and said it was good? What the heck could be wrong?

[ssms5411]

I don't know Mike, mine stays in the 13's even with the 3 big wire upgrades and 200 amp DB altenator, but never had it fall into the red while driving. Your grounds good?

[LETZRIDE]

They look good ....maybe I'll try and hunt them a little more this weekend.

Yours probably shows 13 on your gauge inside the car- but what is it showing with an voltage meter on your batter terminals?

[ssms5411]

They look good ....maybe I'll try and hunt them a little more this weekend.

Yours probably shows 13 on your gauge inside the car- but what is it showing with an voltage meter on your batter terminals?

No it shows on my Aeroforce scanner, ill check it with a volt meter.

[LETZRIDE]

My aeroforce gauge shows the same- but I notice about a .3-.5v discrepancy between my aeroforce and volt meter.

I just ordered a new exciter wire and ironically found my old one from the v6 about 12 hours later... so I spliced that in and the voltage seems to have come up some.

I am now looking at 13.48-13.53v while idling after a drive with the fans on and about 13.63-13.65 idling when the fans turn off... I still have the voltage dropping at WOT but not quite as bad... found my old exciter wire had 3 of the 7 copper strands broken.

I tried unplugging the “ebay headlights” to see if they are the culprit and saw no change in voltage with the voltmeter.

I am now going to look at all of the grounds when the car cools off- I can see the ground strap from the driver side behind the alternator has some green corrosion on it in the center of the strap, so I will trace it down and maybe run a new 4 gauge wire to that location... hopih this may conclude as a ground issue and I get lucky

[ssms5411]

Good to hear.

[LETZRIDE]

So I pulled off all the grounds I could find, sanded them down, cleaned them up. I pulled out the ground strap from behind the alternator and it was full of green corrosion. I replaced it with some spare 4gauge wire I had lying around.

Fire the car up and I get 14.xx volts on cold start- great I think it’s fixed... go to back out of the driveway and I can see the volts dropping... go for a drive and anytime I am above 2500 rpm the voltage is in the red. If I put the selector in 2nd gear and drive above 2500rpm for 5-10 seconds my check gauges light will come in due to low voltage.

I am stumped- is it back to being the alternator? Is there another way to test things?

[ssms5411]

I don't know Mike , hows the harness going to the altenator? I had to replace mine it was just old.

[ssms5411]

Can the auto parts store, load test a altenator to see if its bad. Thats what i would do. Can't be too many causes for what its doing.

[LETZRIDE]

wiring in the harness appears good as far as I can see.

Got back from the alternator shop and this is the outcome:

Bench tested the junkyard truck alternator and he believes it to be good - proper charge at idle (14.6-14.7) - however he could not apply a load to the alternator due to some machine issues. He opened it up and the alternator was a rebuild in the past - but appears to have full brushes. He said the only thing he could see being wrong with the alternator is possibly the rotor is stuck open.

Bench tested the stock alternator - tested good - opened it up and found the brushes were worn all the way down however the guy said although the alternator is "junk" it wasn't displaying black marks on the slip rings indicating that I should be having the type of problem I am having.

He believes my problem is on the car as opposed to the alternator and his theories are as follows:

1) wiring (however I just ran all 4 gauge wiring from the battery to alternators/starter about 1.5 years ago and it all appears to be in great shape. I also replaced the exciter wire eliminating that.

2) belt slip - however, this problem existed both with the factory tensioner as well as I installed the katech manual tensioner - I see no evidence of belt slip

3) He has asked if the harmonic balancer has separated from the crank pulley causing the crank to spin but the alternator not to spin as fast as it needs to. I plan on marking the pulley right across with white out to see if I have movement...I am doubting this scenario because I am not experiencing overheating and I would imagine that the water pump would spin much slower if this were the case as well.

I also took a modified jumper cable to connect to the back of the alternator directly to the battery and I am to take a ground cable and put it directly to ground from the alternator casing to ensure that wiring is taken entirely out of the equation.

I honestly think there is a very slim chance it is either of the two scenarios (wiring since it is new or pulley slip) ...so short of this I suppose the next step is replace the alternator but I am completely stumped.

[ssms5411]

Yeah. Thats about the only thing to do next. Hows you tensioner, i had to replace mine recently, it wasn't that old either may 3-4 years. Good luck

[LETZRIDE]

turns out it was the alternator...I am going to do a writeup on how to check the alternator because I learned a lot of great things in diagnosing this headache.

The old alternator and junkyard alternator both bench tested good - so that means the rotors inside must of been stuck open.

[ssms5411]

Nice glad you found it.