Electrical Problem

[GTJake]

When the car is off and you touch a volt meter to the power cord on the alt and a ground it should be zero, correct?

Well, mine says 11.80 volts. So does that mean I have a drain somewhere? When the car is running I touch the volt meter to the power and a ground and I get 11.50 volts or so.

I hid a bunch of wires, but I have no idea what I should check. I checked all the connections going from the alt to where ever and they're all good. What should I look for?


Please help me....I want to drive my car!


Thanks,

Jake

 

[GTJake]

Also, when the car is running the volts from the batt are 11.53. And when I rev up the car the volts coming out of the alt don't change. This is a brand new alt too.

Please help!

Jake

 

[mo_dingo]

Also, when the car is running the volts from the batt are 11.53. And when I rev up the car the volts coming out of the alt don't change. This is a brand new alt too.

Please help!

Jake

So when you touch your DVM to both terminals of the battery, you only get 11.53V? Even with the car running?

That means your alternator is not charging your battery. You should see at least 13.6V minimum. I don't know why the alternator isn't charging though. But if you probe the charge wire and a ground with the car running, and you only see the battery reference voltage (which is 11.53 b/c your batteries are partially drained), that means your alternator is dead. Swap it or tear it apart and fix it.
Scott

 

[GTJake]

Here's the deal.

I see 11.53 volts from the batt when the car is running.

I see 11.5 volts from the batt when the car is off.

I see 11.8 volts from the alt when the car is off.

I see 11.5 volts from the alt when the car is running.

I think there is something wrong with my wiring harness. I hid a bunch of wires during the down time while the heads were getting redone. But I reconnected everything right and the only wires I extended were for the horn and the passanger side headlight and all those work.

What would cause the alt to not charge past 11.5 volts when running? Remember this is a brand new alt and voltage regulator.

I am completley stumped! Please help!!!

Jake

 

[LoudToy958]

First, make sure the wires on the back of the alternator are connected. There is a plug that connects to the power distribution center. Make sure it is connected. Next, I am sure you went with aluminum heads, there is a chance your alternator is getting no ground. Put your meter on one of the bolts that holds the alternator in. If it reads any voltage, get a 4 ga ground wire, connect it to the bottom alt bracket, and then ground it to the frame. A good place would be a sway bar bolt.

If not, it is either the alt - I doubt if it is new, or the wires on the back of the alternator. They tell the alt to charge when the car is on. If they are incorrectly connected, it won't charge at all........

If you guage panel is out of the car for some reason, the alternator will not charge at all. Just a FYI........

 

[GTJake]

Got it!!

Thanks alot to everyone who helped!!

The deal was one of the connectors that has male and female end was screwed up. There were four female ends in one plug and only three of them were showing when I disconnected it. So I took a needle nose and pushed it back in. Now my volts read 14.5 and I'm happy!!

Thanks,
Jake

 

[Grn92LX]

Jake, you'll have power at your alternator with the car off. I just went out and checked mine and I got 12.93v at the alternator and the same at the battery. Car was off. I have a 130a alternator with a 4G power wire and I have a 4G upgraded ground wire from the engine to the chassis.

How old is your battery?

 

[HISSIN50]

Great advice from Shane et al. Mike is right - the alternator cable shows battery voltage.
As an aside, a discrepancy between the alternator voltage and battery voltage indicates the voltage drop in the charge cable (I dont like to see more than 500 mA drop. I.e. If the alternator reads more than .5 volts higher than the battery, that is not great). This is not to be confused with your battery issue, which might have simply been the discharge while you figured this out. I would trickle charge the battery and see how it does.

Nice work figuring it out.