# Electrical Problems



## dahd11 (Feb 25, 2011)

I have a couple electrical issues on my 68 GTO that are bothering me and need help.

My first issue is my lights. My blinkers and brake lights work perfectly until I turn on my headlights. Once I turn my headlights on, only one headlight comes on, and my left dash blinker comes on full time (not blinking) on my dash. The left blinker will not blink, but my right one will. I am not sure what to do. 

My other problem is there is a drain on my battery. I used a multimeter, pulled the fuses and have decided it has nothing to do with the fuses. I then hooked up the multimeter up to make sure the alternator was charging fine. It was charging it up to around 14.5 volts (normal). (Currently I am disconnecting my negative when I shut the vehicle down, and it is not a huge deal but would like it fixed.) What should I check next? Could it possibly be the diodes on the alternator? 

Thanks for all the help I have already received from this forum!


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## Eric Animal (Oct 28, 2007)

The light issue sounds like bad grounds (common problem) Battery drain....do you have an aftermarket stereo??


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## 1970 Lemans (Jul 25, 2009)

If it was an alternator diode, your dash generator light would stay on even when the engine was off and the key out of the ignition.

You said it you decided it wasn't the fuses because you pulled them ... and then what? How do you know you have a battery drain? Is cranking difficult the next day, or other ... and the problem doesn't resolve when you pull the fuses?

Also, may be two separate problems inre your lights and battery issue.


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## dahd11 (Feb 25, 2011)

Thank you for both of your responses. I am fairly confident that the two issues are not related. (It would be nice if they were, but I don't think they are.) 

If I were to leave the battery cable connected to the battery the car will not turn over after about 24 hours. I hooked my multimeter between my negative clamp and negative post on the battery, and pulling the fuses had no significant effect. 

And yes, there is an aftermarket stereo installed in the car. It powers up, but does not play. Maybe I should try to pull the power off of it. ??

The GEN light is always on, when the vehicle is on. I always have the battery disconnected, so I am not sure if it is on when the key is not in the ignition.

Where are the grounds for the lights? I have poked around with the taillight wires, but don't really see anything obvious.

Thanks!


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## 1970 Lemans (Jul 25, 2009)

You might want to check (re-check) some of the following:

1. Hook up your battery and see if the dash generator light comes on (no key in ignition). If yes, then you probably have a bad alternator diode. If not, then no.

2. I would pull all the fuses and let it sit overnight. Replace and then see if you can start. If yes, then it is likely a current leak through one of those circuits ... if no then it is likely something else. I had an analogous problem. Turned out my glove box light was staying on overnight and draining my battery (old), making morning cranking sluggish.

3. What about the battery itself? It may be on it's last legs and just doesn't hold a charge well anymore? You might go to a schucks (or o'reillys now) and have them check it out.


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## dahd11 (Feb 25, 2011)

I will definetly check the GEN light thing.

Battery is brand new. Again, pulling the fuses did not budge the multimeter which reports the drain from the battery.

Any ideas on my lights? I really kind of think it has something to do with a ground, but not sure where to check.

Thank you for your response.


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## 1970 Lemans (Jul 25, 2009)

Well, the ground should be located behind the headlight ... I think attached to the support structure with a sheet metal screw. At least that is how it appears from a diagram (for '70). You will probably need to pull out the headlight and look/feel around ... maybe look to see if there is any difference from right (working) to left (not working) side.

Just out of curiosity, how much current does your multimeter indicate is being drawn?


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## dahd11 (Feb 25, 2011)

The multimeter was sat on 10A and it was reading 2.25. Which I believe would be 2,250 milliamps. I read where the milliamps should be between 25-50 with the car turned off.

Thanks!


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## Rukee (Feb 8, 2007)

Try unplugging(disconnecting) the wires from the alt and see if the battery drains. If it is the alternator, then it should start the next day if the alt wires are detached.


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## 66tempestGT (Nov 28, 2009)

there is a ground on each side. cleaning them should help your lights a lot. you might additionally have a bad connection inside your park light socket. glove box light is a common drain.


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## dahd11 (Feb 25, 2011)

Not sure why I didn't try that Rukee. I will try that Sunday. (May just hook up the multimeter so I will know a little quicker.)


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## dahd11 (Feb 25, 2011)

I am going to pull the headlights and poke around. I looked behind the taillights and did not find anything that appeared to be a ground. Saw the wires that went to the taillights and blinkers, but I was hoping for something that looked like an obvious ground. Are there ground wires back there somewhere?


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## 66tempestGT (Nov 28, 2009)

i doubt you need to pull the headlights. just look in from the engine side. might be behind the battery. im not sure whats in the way on the other side.


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## Jeff's Classics (Feb 24, 2010)

66tempestGT said:


> you might additionally have a bad connection inside your park light socket. glove box light is a common drain.


:agree:agree
I've seen parking light sockets and even bad bulbs cause the problem you described with your lights. Check all the bulbs and sockets, esp on that side of the car. Could be front or rear.
Jeff


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## Eric Animal (Oct 28, 2007)

:agreeAlso sometimes an aftermarket stereo and/or amp requires power for memory. My 67 had this issue....I just switched the supply to a feed that was only hot when the ignition was on..........Also the glove box light AND the console light are not of the best design either/or are notorious for staying lit as the switch gets loose.


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## dahd11 (Feb 25, 2011)

Thanks guys! When I tap on the left headlight (the side where the blinker is stuck on) all of my lights work. I am going to take some time in the next couple days and take it out. It looked like it was just three screws so it should not be a big deal.

Thanks again!


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## 68GTO4004Spd (Jun 19, 2008)

Check your voltage regulator, that could drain your battery also.


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## dahd11 (Feb 25, 2011)

Where is your voltage regulator and what does it look like?
Thanks!


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## 68greengoat (Sep 15, 2005)

Your voltage regulator will be bolted to the firewall and will look like this:


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## dahd11 (Feb 25, 2011)

Just wanted to follow up on one of the electrical issues, which is the lights. The problem was simply a loose connection on one of my headlights.


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