Hey guys, I am having trouble with my 68. I recently inherited the car from my father-in-law. I've helped him purchase the car about 8 years ago and have worked on it several times but I'm better with mechanical than electrical.

The car has sat mostly untouched except for the occasional start up in the garage for the last 3 years. About a year ago it kept draining the battery, even when left on a battery tender. After 2 new batteries by my brother-in-law he gave up working on it. I brought the car home a month ago and here is what I'm running into -

• It has a drain on the battery whether a key is in it or not. When I picked it up, the wipers cover/cowl cover was raised and wouldn't go down with the key on even with a charger hooked to the batter to provide voltage. After messing with the switch and turning it to ACC a few times the cowl cover went down.
• Any time the key was in ACC or RUN the door buzzer and turn signals would intermittently flash on and off, like they were getting feedback from something else. Once in every 10 or so attempts the key switch would work and I could start the car with a jump pack but it would often die with loss of electricity within 30 seconds to a minute.
• It seems to have gotten worse and now with a battery charger hooked up, the lights with flash and buzzers go off intermittently even without a key in the switch.
• Just trying to weed out problems, I disconnected the alternator to make sure it wasn't shorted internally (it was one of the last things my FIL replaced).
• Then I replaced the ignition switch with a NOS unit, and then with an aftermarket switch. Neither switch seemed to make a difference.
• No fuses are blown and all accessories "work" they just have a mind of their own as in they turn themselves off an on when the battery is connected, whether a key is in the switch or not.
• My FIL also had a new stereo installed at a shop about 4 years ago but that seems to work normally other than also turning off and on all by itself.

I have a few ideas, but I'm nervous as to where to start with tracking down this electrical issue. Could it be a bad ground? If so, potentially where? But why would that cause things to turn on by themselves without a key on? Could it be a short? If so where do I start looking?

Sorry for the long post but I'm at wits end and trying to figure this electrical gremlin out so I can drive this thing.
Any and all helpful comments appreciated! If I've missed something obvious, great! Let me know so I can fix it.

God bless,

Reggie
1968 Convertible - 327/4spd

 

Old school for finding a battery drain is disconnect the pos battery cable and then connect a test light between the pos battery terminal and the pos battery cable. If there is a draw the test will light up. If so start pulling fuses until the light goes out. Start with the courtsey light fuses since you will have drivers door open.

 

Maybe try to see what happens if all the fuses are pulled out. If nothing acts up put the fuses back one at a time until you see the problems again. Then you will know which circuit to look at.

 

On 68’s, a common battery draw will be the center storage hatch. Sometimes the light inside the hatch stays on because the switch inside isn’t engaged all the way. I think GM issued a fix which was a washer type spacer. Maybe the spacer is missing or was removed.
Also, if the wiper over ride switch is left on, I think that will drain the battery.

 

Thanks guys, I'm going to try to dive back in tomorrow after church and see if I can track down the short.

 

Search the forum for 1968 energized wiper solenoid. Probably all it is.

 

Many many issues with 68s.
First thing you mention is the key switch. I had a lot of those weird on off electrical issues andvthe switch was bad. NOS is the best way to go there, but it has to be New Old Stock, not a reproduction. The repops are camaro ignitions and are sometimes wired wrong.
Next, there is about 12 grounds behind the dash. Its a nightmare back there. Your best bet is to pull the seats and lay on the floor to see under the dash as to the grounds. Most are for lights and dash gauges, but you need to find the ignition switch issue. Easiest way is to pull your dash off. Go right to left, being insanely careful with the center cluster. If the upper parts breaks off, it can be repaired but you will need to run grounds from the upper piece to the bridcage to make sure it grounds well. The wiper switch is another thing you need a new NOS switch for. The repops break while you test them.
If yuur harness is original, consider saving for a new one from Lectric Limited. Be very careful with the ignition switch plug. Its fragile and they are not sold separately.
Also consider getting Doc Rebuilds Oh So Ez wiring diagrams. They show you each plug in the order they appear in the harness. Call to buy, dont order from the website.
As for the battery drains, THE wiper motor causes a big one if the override switch is left on. It interrupts the wiper switch on the windshield so you can change the blades. When it is engaged, it disconnects the ground for the motor but leaves the wiper park solenoid energized, which kills the battery overnight. Its a rotary switch and should be changed to a toggle switch. I like an on-off-on style so that it is only engaged in the middle position. My knee would hit the **** and engage it all the time without mevrealizingbit. Late 68 incorporated an indicator light so you would know when it was engaged.
The center golve box light was mentioned.
As for the wiper door, it could be a sticking vacuum relay switch, the wiper door actuator ssticking, or the door open vacuum solenoid on the back of the tach. They rarely fail but it happens.
If you have a multimeter disconnect your battery positive side and put the meter in the amperage mode and connect it between the positive post and the positive cable. It should be a very very very low reading due to the clock running and the radio memorty. If it is just about zero, have the battery checked. It could be bad,....
Most likely you will be reading something less than an amp. Pull all the fuses and see if it zeros, paying attention to the meter after each fuse. Then unplug the wiper motor, then i would disconnect the alternator and the horn relay.

 

I believe that Rescue Rogers has given you the real low down on the 1968 battery drains, his information is correct and I would follow the suggestions he has made for you. His answer is very comprehensive and has a lot of meat in it for you to use. Read it carefully and you will likely find the battery drain in your Corvette.

We have a 1968 Corvette that my wife and I bought 34 years ago and have enjoyed it very much. Be warned however the 1968 is very different from Corvettes made the following year. It has been a learning experience for the past three decades

Harbor Freight carries a small tool that plugs into a fuse slot and will show you any current flowing in either direction. The cost is about $20 and it is called a Cen-Tech 20A Circuit Tester and they offer it in a couple sizes for various vehicles. On the 1968 I have had to make an adapter to allow the tool to work with the old glass fuses. It is a very handy tool to have in your tool box.

Another tool that would help you out would be a "Power Probe". With this tool you connect the long cable to the battery directly and then you can test your system with the ability to supply 12 volts at the tip or Ground at the tip by simply using a rocker switch. Using this tool you can see if circuits are working by energizing them individually and testing components is easier than ever. This tool became so useful in my world that I bought a second one for working on my C4 and its EFI system.

DocRebuild.com sells nice wiring charts and vacuum charts. He also sell other great parts for our Corvettes, I have used his vacuum hose kit and had no problems for over 2 decades.

Best regards,
Chris

 

tobnHisglory
Before you go off the investigate the known universe check your wiper solenoid. If you interrupt it's operation the solenoid will remain energized whether the key is on or not and cause a siginifcant parasitic draw on your 68 (yes, it's wired differently from later C3s). Your wiper door/cowl comment makes me think you got this going on and there may be nothing else really wrong.

Here- I wrote this a couple of years ago.
https://www.corvetteforum.com/forums...post1607052246

 

Just wanted to give a quick update. I've had pneumonia so I haven't been working on the car much the last few weeks. Finally made it back to the garage today, reinstalled the NOS ignition switch and pulled all the fuses. I believe I have isolated the circuit that was making things go haywire to the fuse that is marked stop/haz. When that fuse is in, things go crazy, lights flash inside and outside the car, including instrument panel and courtesy lights. Not sure what is next in fixing it, but its a tiny bit of progress.

 

try pulling the hazard flasher and see if it goes away, maybe the flasher is shorted. I think its the one in the fuse panel, there is also a flasher can under the center console, forget which one is which