CamaroGuy83

Hey guys, well my '98 Z is having a weird problem i can't diagnose. At night sometimes, my lights "pulse" is the only way i can put it. ALL of my lights, dash, headlights, climate control lights, dome, and my voltage gauge "bounces". It always stays over 13 volts, but sometimes its way over, and sometimes just barely over. I replaced my alternator w/a truck alternator, thinking this would fix it, but now this alternator does it too. And when it does it, it does it bad. Like my lights look damn near like strobes. Some times, if i rev my car, it will quit. Its annoying as hell at night, so i need some input guys.

Thanks,
Chris

RedHotG8

iTrader: (1)

It sounds like you have a loose main ground connection to me.

Darkman

iTrader: (2)

If you have headers, I would check all the wiring that comes close to them. Semi-burnt wires can produce intermittant symptioms like yours.

CamaroGuy83

Alright thanks man

CamaroGuy83

I don't have headers sir

CamaroGuy83

Anybody had this problem with their car? I heard its kinda common on f-body's.

Adam2001WS6

iTrader: (1)

I don't know about it being common. You said you replaced the alt. so I'm in the same boat for checking your ground.

CamaroGuy83

Alright i'm gonna get under it this evening and examine and see about the loose ground. Thanks guys

technicalninja

iTrader: (1)

Grounds-grounds-grounds!
Don't just check them, take em apart, clean any corrosion, retighten. Some times I'll put "star" washers between the connector and what it is grounding to. Add grounds, Extras never hurts!
Fiats are well known for one of the worst electrical electrical systems. After adding um-teen extra grounds my wifes 79 X/19 (worst of the worst!) went 80k without a single electrical issue.
You don't need those fancy ground wires I've seen sold on the internet. Just high quality normal 10-12 gauge wires with clean connectors (I solder them).

Looking for burnt or otherwise compromised power feed wiring is a good idea too. Car been in an accident? Look at harness in the damaged area.
In 20 years of wrenching 95% of the truely weird electrical gremins have been created by what ever was done to the car last!

Best one I ever diagnosed was a BMW 7 seires that was popping main fuses occasionally. Other mechanics had removed the dash and interior and the car's wiring harness was completely un-loomed. A disaster! Took about 5 min to find it as the car had been recently painted. When the bodyshop re-installed the fr bumper they pinched the wiring loom to the front electric fan. I released the harness, taped up the TINY bare spot in feed wiring and sent that critter BACK to the "other" mechanic to re-assemble.

One last possibility is having a truely strange diod failure in the rectifiers of the alternator. Having this same exact trouble on two? Doubtfull in my book.

O2Form

Both my 02 Firebirds do it! I tried alot of different things and they still do it. I think its the voltage regulator.

CamaroGuy83

Yea i checked all grounds and they were all fine. I thought it was my regulator too, but i replaced the whole alternator and it still has the problem. Kinda lost here.

RedHotG8

iTrader: (1)

Did you remove the grounds and clean the surfaces and reconnect them?

technicalninja

iTrader: (1)

Just spoke with one of my still currently wrenching buddies about this.
Does your positive terminal connection at the battery have two large wires that overlap each other? If it does peel the rubber covers back exposing the interior copper connectors and clean these up real good as well. One goes to starter and other feeds everything else. Corrosion and looseness here will cause your symptoms.

Just for grins add a second ground from the body to the negative terminal of the battery. I'd just clip onto the negative side with a set of jumper cables and clip other end to a firewall bolt somewhere. See if this makes any difference.

And lastly have you tried a different battery? It's a strech to call out a battery here but should you have another available for testing it's worth a try.
2 days ago I had to replace a battery that caused MASSIVE INSANE flickering on my wifes Odyssey after shutdown (she had left the head lights on). It also would not start the car.
A really strange short between the plates in a battery might cause this.

Duke_Z28

iTrader: (1)

I also have this problem, was told it was likely the voltage regulator by a mechanic, and I will be putting in a new alternator this week while I have the car apart for a cam swap (its the original '98 alt and probably could use replacing anyways).

My flickering tends to be worse in cold conditions but gradually goes away as the motor heats up, is yours the same? Does anyone think that this would point to a different issue?

RedHotG8

iTrader: (1)

Metal expands when it's warm and contracts when it's cold, so that would explain why the metal electrical connections get better as it warms up.

Duke_Z28

iTrader: (1)

Partly true if memory serves correct, because the physical connection is improved, but many metals, especially conductors have increased electrical resistance with increased temperature. So heat CAN help connections, if they are physically loose, OR can hamper fine-tuned electronics into intermittent failures, and since I'm not experienced enough to have a good guess between the two its back to square one...

I guess this is why I can not distinguish if my case is different, as I do not know the wiring of a voltage regulator, and I was wondering if anyone else with this problem had noticed if their car seemed to get better as the car reached running temp.

RedHotG8

iTrader: (1)

Actually I know very little about electricity, but I do know that there needs to be a good clean connection for conductivity. Since our cars are subjected to moisture it's easy for the metals to corrode causing a bad connection. Id say do what Technicalninja suggests and if it doesn't get better dig deeper.

O2Form

thats how both my 02 firebirds act, my 99ta doesn't do it.

technicalninja

iTrader: (1)

If ya'll really think your having alternater trouble the test for this is easy. Get an oscilloscope reading on your alternators main lead.
A good pattern will look like a bunch of little small equal humps. A bad pattern will have violent spikes everywhere.
There are small handheld scopes available now (look like a DVOM but have a bigger display) one of these will work fine.
Nother source for scope: A "real" alternator rebuilding shop. Might be a bit hard to find but they are out there. A real good shop might even scope one for free. They are hoping you'll buy from them and a nasty pattern is an excellent sales tool.
Most normal shop ignition/ecu scanners can do it as well.

CamaroGuy83

After cleaning my neg battery terminal it is not as violent of a pulse/flicker.