Topic: 1979 Formula Battery Drain

[DanielHubbard]

I have been looking over posts about battery drain problems, since I have one on my 79 formula.  One suggestion was to pull the alternator leads, then check to see if the battery cable still arcs when reattaching it.  Well, tried that, and the arcing stopped with the alternator leads disconnected.  Next, the advice said to reverse the alternator leads and try again.  Did that, and the arcing was there again.  So, where to look next?  Bad regulator in the alternator?  it's a remanufactured alternator and is pretty new, so i'm sorta discounting the bad regulator idea.  And yes, the interior lights are all off, the glove box lamp is out of its socket, the trunk light is off....

[ponchonutty]

The best way to figure it out is to have a testlight in between one lead from the battery.  If there is a drain, that will light up.  You can start pulling fuses or unhook the positive cable from alternator and see if the light goes out.  As soon as it does what ever you remove or unhook, that's where your problem is.

[81Turbo TA]

 Sorry if this sounds stupid, I just need things drawn out simple.  when you say "testlight in between one lead from the battery",,where exactly do you mean,,,,the actual battery cable or somewhere after the fuse panel?    I have the same battery problem, and i need to understand this.

[joe d]

thank god ponchonutty chimed in as someone gave you a horrible way to test it, what he means is to disconnect the negative side of battery, install a test light between battery and neg cable, if it lights then you know you hve a draw, start with a helper disconnecting fuses one by one until the light goes out, i would also depress the door jam plunger while doing this s the dome will show a draw, when the light goes out then you found your draw

[81Turbo TA]

Thanks,,I cant wait to try this and see what it turns up.  So far with my doors shut, the dome light lights up dim,,problem number 1.

[joe d]

Thanks,,I cant wait to try this and see what it turns up.  So far with my doors shut, the dome light lights up dim,,problem number 1.

sounds like a bad plunger, open the door and press the plunger by hand, see if the lights go out

[DanielHubbard]

battery held through the weekend with the alternator leads disconnected.  I only unplugged the two wires with the plastic connector.  I didn't unplug the thick positive wire from the battery.  Any idea what i should look for?  A bad alternator? 

[joe d]

plug the alt back in and follow the instructions above

[DanielHubbard]

plug the alt back in and follow the instructions above

Anyone else have any advice other than joe d's?  I was hoping for a more specific place to check, rather than a brute force, check everything approach.  Disconnecting the alternator leads doesn't narrow the focus any?

[brian c]

If I read all that correctly....with the Alternator connected your battery drains rather quickly. With the (2) prong connector disconnected from the Alternator, you battery maintains its charge. Did I get that correct?

If so, you may be looking at either a wiring issue in the exciter circuit (that's the 2 prong connector you disconnected if I recall correctly) OR an internal short in the Alternator. This assumes NOTHING else has been added to the car electrical wise. Quickest approach would be to pull the alternator and have it tested for shorts. I believe Autozone will do this for free.

If your wiring was anything like mine, Read: Some redneck yahoo wannabe electrician who had no idea about the form/function of electrical tape hacked my harnesses, you may be better off just replacing underhood harnesses with brand new.

Post some pics underhood so we know what we are dealing with.

**If you're not going for originality a single wire GM alternator WILL work. Just tape up the 2 prong connector and move on. IF you do this conversion, you will need a line from the + battery post to the + connection on the Alternator.

[joe d]

plug the alt back in and follow the instructions above

Anyone else have any advice other than joe d's?  I was hoping for a more specific place to check, rather than a brute force, check everything approach.  Disconnecting the alternator leads doesn't narrow the focus any?

this is not a hard test at all and quite quick on these cars, simpley remove the neg batter cable and install a test light between the battery and the cable you removed, if the test light is lit then remove fuses one by one, at the most this will take half hour by yourself and 10 minutes with an assistant, removing the alt wires disables the entire system and as for replacing the entire harness, hmm i would rather spend the 15 minutes diagnosing the issue

[DanielHubbard]

O.k. Thanks Brian.  You got it right.  With the alt. leads disconnected, it holds a charge, no problem.  I'm going to Autozone tomorrow to have the alt. checked out.  As for the car, well, i got it on a trade (my bad!)  Engine isn't original to the car, and I'm not sure what all has been done under the hood.  The A/C was removed, and I'm not sure where all of the harness is for that.  I've got a feeling I'll find it taped up somewhere.  The dash lights don't work, but I think I know what's wrong with that.  The power windows work o.k., but the windows themselves aren't adjusted right, so they bind against the blow-out clips at the top of the travel.

I will post some pix of the underhood area tomorrow evening after I get everything sorted out. 

By the way, my '80 TTA has a similar problem with the battery draining...   sigh...

[DanielHubbard]

Well, didn't pull the alternator tonight (had to swap out a bad alternator on the boat!).  But, did check out the wiring and do a little more narrowing the focus.  With the white wire connected to the alternator, and the two thick wires connected, but smaller red wire disconnected, got a big spark off of the negative battery terminal when connecting the neg. cable.  Without the white wire (or smaller red wire) connected, no spark.  That means the drain is coming off of that white wire.  The white wire was spliced to a brown wire, which runs into the bulkhead connector going through the firewall.  Thus, the drain must be in the interior somewhere.  Sigh...

[joe d]

hmmm, now maybe start pulling fuses to find which circuit

[DanielHubbard]

At least I've cut my search area down, even if it's just a little.  That's what I was looking for, a logical way of dividing the problem into where it is and where it isn't.  Now I know the problem isn't under the hood, I can stop looking there.  If it was something wrong in the alternator, might be kind of hard to find that by pulling fuses looking in the interior.  So, I will start with either a meter, or a test light, and my son, and start trying to isolate circuits on the interior side.  Since I don't have any courtesy lights working right now, and no glove box or dome light installed, should be able to narrow it even further. 

On the bright side, no pun intended, I did fix a grounding issue between the dimmer switch and the dash, so all of that is good now.  Too bad my tach still reads 6000 rpm when it's idling.