Headlights and tail lights drawing to much power! Help

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DusterJohn

DusterJohn

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I have no clue what I'm doing when it comes to wiring so I need some help here. I have a 1975 plymouth duster with a 318 and the alternator reads fine and charges good when the lights aren't on but when I turn on my lights it drops to a negative charge and draws from the battery I have no idea what's wrong or how to fix it so can anybody help me figure this out it would be greatly apreciated!
 
When you bring the RPM's up a little does the guage go up into the positive?
Your charging system may not be working.

If it does, then that is pretty normal for these old girls.
There are things you can do about it though, like better bulbs, LED's and such.
 
are you still using the old amp meter or are you looking at a volt meter?

either way, the readout should go up with revs...at least a little
sounds like a bad alternator to me but if the battery maintains enough juice to crank the engine day after day that cant be it
 
put a volt meter on the battery, car should be charging in the 14 volt range when running, no less than 13.5 imo. if it's showing 12 or less your not charging.
higgs
 
diymirage said:
are you still using the old amp meter or are you looking at a volt meter?

either way, the readout should go up with revs...at least a little
sounds like a bad alternator to me but if the battery maintains enough juice to crank the engine day after day that cant be it
Click to expand...

Right, so how long has the car been running like this?
What is the volt reading at the battery?

We will know where to go from the answer of those two questions.
 
could it possibly be the voltage regulator because I've had to replace that several time in the past
 
And I don't have a volt meter I'll have to get one tomorrow to tell you, and it's been like this for a while now. But I do have a battery charger that has a alternator test on it to see if it's good or not I'll check that right now.
 
Check the belt for wear and adjustment,, a loose belt will cause similar symptoms..

but discharging at idle with lotsa things turned on,, is not un-common, as mentioned..
 
Loose belt, bad grounds may cause undue strain.

Check and clean all fixture grounds, front and rear. Make sure battery terminals are clean. Make sure battery and alternator are good.
 
DusterJohn said:
could it possibly be the voltage regulator because I've had to replace that several time in the past
Click to expand...

We can find this out when the time comes, as one of the things that makes these kinds of posts hard to follow for everyone involved is jumping around from one thing to another without finding out some of the for sure answers.
Of course cleaning and checking postive and nevative connections can be done whenever you feel like doing it, and you may find you cleaned something that made a difference.



Find battery voltage.
See if it climbs when you rev it.
When you get a second or two note how many wires are connected to your alternator.
There is a real easy way to see if the alternator works without taking it off, but we'll get to that if we have to, so don't take it off just yet.


Bad Sport said:
Loose belt, bad grounds may cause undue strain.

Check and clean all fixture grounds, front and rear. Make sure battery terminals are clean. Make sure battery and alternator are good.
Click to expand...
 
Okay wow I'm so stupid it was the belt just a little bit loose haha it's all good now! I just changed the alternator a month ago cause it went bad, and I guess I just didn't make it as tight as I thoght, but thanks for the help everybody!
 
inertia said:
Check the belt for wear and adjustment,, a loose belt will cause similar symptoms..

but discharging at idle with lotsa things turned on,, is not un-common, as mentioned..
Click to expand...

Bad Sport said:
Loose belt, bad grounds may cause undue strain.

Check and clean all fixture grounds, front and rear. Make sure battery terminals are clean. Make sure battery and alternator are good.
Click to expand...

OMG, you two nailed it.
Bit by my own philosophy (Start with the easiest thing first) :D
 
DusterJohn said:
And I don't have a volt meter I'll have to get one tomorrow to tell you, and it's been like this for a while now. But I do have a battery charger that has a alternator test on it to see if it's good or not I'll check that right now.
Click to expand...

I know that you found the answer to your problem, but you might want to buy a good multimeter anyway when you get the chance.

It's a very handy tool to have, and they're inexpensive. I have an Actron digital multimeter that I picked up at the local Auto Zone for around $40. I cannot tell you how many times I've used the thing over the last 6 months.
 
I love posts like these. It shows the importance of such little details. Also it reminds all of us that we do sometimes forget to check the little things first. Lol I'm guilty. I know a lot of other guys are too. Haha.
 
Agreed. Don't need madelectrical method of rewiring the car in every case.
I will suggest taking a closer look at that belt. If its over 5 years old I would replace it.
If its growing in length it will continue and fail.
 
hollywood hig said:
the current harbor freight flyer has a coupon for a free volt meter. just thought i'd let u know...
higgs
Click to expand...
I've got 7 of those and keep one in each car. Also, get their cig lighter LED voltmeter, or if you really splurge a digital display one (Amazon $15).

In the old days, people did the opposite. They would run with headlights on in the daytime to "recharge the battery". At least that's what everyone said when you saw a car on the interstate with lights on. Probably had to do with voltage drops in the harness stimulating the Vreg, or maybe bogus.
 
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