Interior Light staying on

[Mattrix]

Hi all,

Just having some electrical issues with my '78. The interior light kept staying on and draining my battery. (or so it seemed that it was the light draining the battery). So i pulled the globe out, and found that the battery is still being drained somewhere else. Does anybody have any ideas where the charge might be going? What else is likely to stay on in the car when i turn it off and close it up, that could possibly drain the battery? I'm pretty sure it's not my alternator playing up, as it was all fine until the light started staying on and then that's when all the problems started...

Need to try and work it out, as I'm going to be installing a security system, which obviously won't work if i have to disconnect the battery every time i turn the car off (which is what i'm doing now).

any suggestions etc are appreciated

Matt

[Chromie]

Hi Mattrix ;42
The late 1970's had an interior light delay relay which if fitted to your Corvette may still be draining current.
The front pillar switches are adjustable as yours may not be making contact with the door when closed.
Some times the pillar switch wires fall off and short out in the pillar as well.
Check your rear compartment light and your glovebox light as sometimes they are still on even though the door is closed
Also some radios draw current
Next is check your clock
And finally check your battery gauge (ampmeter)
If after all that you will have to take it to an auto electrician
It is just a matter of connecting an ampmeter between the positive battery cable and the battery terminal and slowly dissconnecting electrical items while watching the ampmeter for a current drop.;27

[nifty]

i would try the voltage regulator... is alt light staying on when you driving? if not does alt light come on when ignition turned on?...i had this problem with my hq... the damn alt light globe was blown and i didnt know it was on,wondered why i kept getting flat batteries.

[Mattrix]

Thanks guys i'll have a look tonight and see if i can work it out. Pretty sure it doesn't stay on while i drive, but i'll do a bit of a process of elimination and post back in here my results :)

[daniel42au]

My C4 had basically the same electrical fault... I would come back the next day to a dead battery.

In the interior lights circuit, was an electronically controlled timer(i.e. a little box behind the dash).  Its purpose is to turn off the interior lights after 30 secs or so after the doors are closed.   Unfortunately, intermittently it would remain on and i would come back in the morning to a dead battery.

Initally, like you I figured that there was an open circuit in the car's electrics.   My strategy was to put a multi-meter across every fuse in the fuse box to see which ones were pulling current when they shouldn't be.

I zero'ed in on the interior lights, so I started hanging around every time I exited the car to watch the lights go out.... I thought I was wasting my time till.....eventually the time came when the lights stayed on.  

It turned out that in the timer cct there was a diode on the blink... Cost $1 at Jaycar electronics.    The replacement cost of the box was to my recollection about $69US... so i replaced the diode.   I dont know if your C3 has the same set up or has something else such as a door actuated switch only.   Anyway, the GM workshop manuals with electrical diagrams from EBay are worth the expense as well as making good bedside reading when ya get sick of watching the repeats on Cable TV.

[Cameron 77C3]

With motor off and ignition key removed.

Disconnevt battery positive terminal.  Get a multimeter and set multimeter to 10amp DC scale.  Connect one wire of multimeter to positve terminal of battery and the other lead to for mentioned disconnected battery lead.  Read amps. If you read a number then something is pulling power.

If it's decimal number, eg 0.2, then it's your clock, alarm, etc.

If it's a whole number, eg 1.2, then its majour.

Start removing fuses one by one to help pin point the area.

Interiour lights are usually the problem.  I know my 77 also has a light above the spare wheel that comes on when the door is open.  If you have a faulty door switch.............

Also what about foot well courtsey lights???????

Let us know what ya find.

[Mattrix]

Thanks again guys. Probably going to attack this today so hopefully something turns up, that I'm able to easily fix. Then again, if nothing turns up and it's not having the problem anymore, even better! :) Will let you know how I go

[Mattrix]

Well, it appears that it's not happening anymore. I've had the battery hooked up since sunday and it hasn't lost a scrap of charge. and that's after i've fired the car up on sunday, and then left it sitting there since then. So, I think i'll just keep an eye on it but hopefully it's fixed itself... Oh and all the interior lights still work, funnily enough. Maybe it was just the switch playing up...

Oh well, now it's time to install the security system. fun!

[Cameron 77C3]

Don't forget depending on your security system, if the door switch plays up again it could trip your alarm.

Just food for thought.

Cam