toyvet1

Monday night I made a stop home after work. Car sat for 15 minutes and wouldnt start , signs of a dead battery. I had no problem before this with charging. I slow chearged for two days and regular charge for another 24 hrs. Battery wouldnt hold a charge so I replaced the battery. Within 24 hours new battery was totally dead.
After charging the battery overnight again as soon as I hooked up the battery the voltage drops from 12.5 to 6 and you can see the voltage drop. I have all my high amprage things off tha aletrnator so I disconneccted the fans, headlights and the alternator. Still big draw. Next was power windows and fuses one by one. Still a big drain on the battery. Any ideas....

Its a 1979 highly modified so it hard to list all the changes...

thanks,,,,

Roughrider

A not uncommon problem is the convenience light timer going bad. Check and see if your interior lights are staying on...or even coming on at odd times.

The timer is an orange thing that should be located behind the glove box on a '79. If this is your problem, they're available from the normal vendors.

...Roger...

If it is your timer check out Willcox. He builds the insides for a big savings over buying the complete unit.
http://willcoxcorvette.com/product_i...ducts_id=26882

0Willcox Corvette

My first suggest would be to pull the timer from the car and see if the drain goes away.

My bet is it will.... If not post back.

Willcox

Rick_V

I am having a similar problem but not a severe when the car sits for a few days it loses power to the point of needing a jump. I the timer even necessary? I mean does it do anything but keep the courtesy lights on after you close the door?

0Willcox Corvette

The timer is not necessary and we do make a bypass board that will allow your doors to operate like a regular car. If you remove the timer your interior lamps will not work unless you do a re-wire job on it.

Willcox

http://willcoxcorvette.com/product_i...ducts_id=27100 By-pass timer board.

Rick_V

OK so if I replace the board with one of your by-pass board the lights will still work just no delay correct? Just want to be sure.

0Willcox Corvette

Yes this is all you need. The lights operate just like a regular car door. On when open and off when shut. The module is located right behind the glove box. It is just plug and play with no splicing or cutting of any wires.

toyvet1

Got a chance to look at the car today. I pulled all the fuses and breakers and no draw as I replaced all the fuses and breakers, i get big loads with the A/C fuse and Gauge fuse. Either one drops the volts to
9v and both together drop to 6v. So I need to find the common issue on both circuits.

Also i cant find in the service manual what a heavy orange wire with a black stipe that plugs into the lower right BAT terminal in the fuse block, any Ideas?

I also removed a 30 amp fuse and the manual doesnt show a 30 amp anywhere.
Thanks

0Willcox Corvette

Go to this link.. I've isolated it in a schematic for another customer.

But the orange wire is a lot of things..... Mainly it runs the courtesy lamp system, the glove box door lamp, cig lighter, and so on.... Did you un-plug the timer to see if the draw went away.

Something may have cooked the timer such as a shorted lighter or some other item.

http://willcoxcorvette.com/repairand...lp.php?hID=309

toyvet1

I ran out of time before getting to removing the timer. ill get to it tomorrow....

toyvet1

Well the timer did help so ill be replacing that. But Im thinking it also time to replace the wiring harness. To many Gremlins lately. Yesterday the power windows would work and today they are fine. Im wondering if something was stuck causing such a large drain. I reinstalled the timer and everything was okay. Im confused so ill replace the timer and start cleaning connectors.

So as of now the only issue is the tail lamps and dash lamps, two different circuits connected at the switch. So headlight switch will be replaced also.

Im leaving everything hooked up and see how the battery looks in the morning.

Thanks for the help...Ill update after I replace the parts.

...Roger...

Actually they are on the same circuit. If the Tail-lamp circuit fails the Dash lamps ( INST) will not work.

jkjazzsax

I had the same exact problem for a long time in my '78 and it actually turned out that a single wire had fallen on to the headers and burned onto it. It was causing the battery to drain as well as short out.

I'd just check that too while you're at it.

toyvet1

...roger... Im confused by your post. Accordintg to my FSM the dash lights are controled by a 6amp inst lps fuse on page 8a-67. The tail lamps are on a 20 amp tail fuse on page 8a-27. Where do you see these on the same circuit?

I got home tonight and the battery was dead again. Battery held a charge all night and during the day it drained??? The light timer is removed so I guess im back to square one......

Ive check the whole harness and it isnt anywhere near the exhaust or anything to ground to....

Ill wait till I get the headlight switch replaced and the new timer and see what happens.

...Roger...

On your page of 8a-27 you'll see coming from the bottom of the light switch a brown , green and black wires.
The green goes to the 6amp Inst light fuse-the green wire actually "supplies" the 6amp fuse with its power (you were probably thinking the 6 amp got its power from the fuse box-its the only fuse in the box that doesn't get its power from the box).

One other page might help.Go to the first pages , in my book its 8a-12 , figure 8a-8 "power distribution circuit diagram".
Follow the orange from the taillight fuse up into the light switch,through the switch,out the green to the 6amp Inst light fuse,the gray then goes to the inst lights.

toyvet1

toyvet1

It ended up being the poewr antenna. Either the relay or the motor. When I unplug the harness from the relay the issue goes away.

Matthewjt

Thanks guys. This thread helped me track down my battery drain to the courtesy light timer. Pulled it out and the drain dissapeared. I'll have to get a bypass timer board for it.

mrvette

Antique thread, but I have NO courtesy lights in my car....who needs them??? really now???? serious??? simple to pull all the light bulbs and case closed!!!!!