I've got a battery drain on my 68. I have the dash out to replace the drivers side pad so I thought I would work on the battery drain.

Hooked up a test light between negative cable and battery. I pulled every fuse individually and the light never changed. So then I pulled every fuse simultaneously and still nothing. Pulled cables off of the alternator, voltage regulator, coil. Nothing seems to change the brightness of the light.

I guess it could be battery cables. I hate to change them without doing any more troubleshooting.

Any other thoughts? What other loads don't run through the fuse block?

 

Starter. Go back to square one. Lift the cable off the starter, then add it without the hots that go from there. (You just have to swim further upstream)

 

It really just that the old-frayed-wiring. Cleaned it all up, heat shrunk all connections, and got rid of the battery drain.



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Most multimeters have a 10-amp scale for measuring amps so I suggest putting it between your HOT cable and terminal and see how much of a drain you actually have.

 

The ground (black wire) for the wiper and fan motor should connect to a bellhousing bolt near the starter,
check that it is not connected to the top post of the solenoid by mistake.

 

I was fighting a battery drain on my '82 for a long time and finally discovered the drain was being caused by leaving my keys in the lock cylinder. I had disabled the annoying key-in-ignition buzzer but it was still causing a drain even with the buzzer unplugged. By merely taking my keys out of the lock cylinder my battery drain vanished.

 

Look at any stereo or amp connections also check antenna ..

 

So I got a little more technical with it tonight. Put my meter between the neg cable and battery and found I had a 5.1 A draw!

Pulled the positive wire from starter and left the positive battery cable hooked up and the draw went to 0 Amps. Ok... progress. Doesn't seem to be an issue with the positive cable.

I bypassed the car's circuits and jumpered over to just the alternator hot side from solenoid. Still 0 Amps. So I don't think it's the alternator or voltage regulator circuit. (68's still have an external regulator)

Decided to call it a night and study the wiring diagrams a little further.

I'll check the wiper motor suggestion tomorrow. Anybody have any other thoughts for tomorrow?

 

Your doing a very thorough job of testing, post #1 suggests checking the clock and the light in the center rear compartment.
https://www.corvetteforum.com/forums...with-pics.html

 

PB,

Thanks for the link, that's a good write-up.

Keep in mind I have the dash completely out of the car, so clock, light switch, ignition switch, everything is unplugged.

Also, I pulled every fuse in the panel and the draw never went away.

 

Hazard flasher
Horn relay
Ammeter
External voltage regulator

 

My experience is that with the 68 model year, 90% of battery drain issues are related to the wipers, and 90% of 68s have at some time a battery drain issue. The wiper system is designed to drain your battery if the wiper cutoff/freeze switch is left in the "off" position. Pulling the wiper fuse should stop the drain, so based on your troubleshooting to this point you should have ruled that out.

 

Making more progress. I started pulling +12V wires off of the junction block at the horn relay. Pulling the BLACK/ORANGE wire stops the drain. According to AIM this feeds the fuse block. But of course, I already ruled the fused connections out. ARGH!

Those wires connect into the front lamp harness with crimped connectors from the factory. They look very corroded so I'm suspicious about the splices. Looks like some of the insulation is damaged and possibly melted. So, I'm replacing both splices tonight. We'll see if that helps at all.

5A x 12V = 60W That's a lot of power to be going nowhere (heat). So I'm a little skeptical this will fix it, but it's the right thing to do anyway.

 

I had the same problem on my 68. I was finally able to stop the drain on the battery. The problem was the windshield wipers. The 68 has a wiper motor only known to the 68. So any info on any other model or year will not help.
I found a post on another web site May 6th 2012, that solved my problem. It reads as such:
Start the car and turn on the windshield wipers, wet the windshield if you like, and let them do at least one swipe and using the windshield wiper switch turn off the windshield wipers. Now test for a current draw? Reason I mentioned the wiper switch is that if my wiper switch is "accidentally" turned on/off when the car is not running it will pull current until the car is started and the wiper switch is used to cycle the windshield wipers on/off. It is called parking.
The brown wire on the motor will only be hot when the wiper motor is running, and when the wipers don't park themselves (run through the whole swipe process) then this wire remains hot and drains the battery. A strong current draw.
Hope this helps!
Willcox corvette site has some very good instructions on the 68 wiper motor if you need further info.
Since you got every thing apart it might be a good idea to do a dash wire harness. I did mine just because I wanted new wiring and to get rid of all the bubba wiring of all the years.

 

.....that intermittently grounded. Couldn't find it and didn't try too hard until one day the car would not turn off when I turned the key to off. It turned out that I had an intermittent ground/short in the starter solenoid......that would have been really hard to find. Here is my post on that and how I found it:

https://www.corvetteforum.com/forums...s-running.html

 

We have a winner!

I'm still not sure what is exactly the problem, but I was able to stop the battery drain. Turns out that I have to pull the wires on the wiper relay AND the black wire off of the wiper motor. Either alone doesn't work. Fuse by itself doesn't work. Seems something strange is going on.

Here's how I found it in case anyone else finds this helpful:
Hooked a meter in line between negative cable and negative battery terminal. Set it to DC AMPs and watched the numbers. With everything hooked up I had 5.08 A. I pulled EVERYTHING, and by that I mean every single fuse and connector that I could find. I got all of the inside connections apart and started pulling underhood. Once I got to the wiper connections, I pulled the black wire and 0A!!!
Leaving the black wire off of the wiper motor, one-by-one I started putting connections back. Starting with the fuses I basically worked my way backwards. Once I got to the wiper relay (under center console), back up to 5A.

So I'm done for the night, but now need to start working on the wiper system. My wiper system has never worked, but never been a problem with Rain-X on the windshield (and a fair weather car). I know the tach-mounted wiper solenoid is broken, so I'm starting with replacing that.

Thanks to all that helped. I'll post again when I find the actual culprit. But I'm guessing regatta's recommendations are going to be very helpful.