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battery/test light question

jwstewar

jwstewar

Active member
My father-in-law has been working on that Vette he bought. It has some type of battery drain. Now we have ourselves confused. With the negative battery cable disconnected, if you put a test light between the cable and the neg battery terminal, will the test light, light?
 
muleman

muleman

Gone But Not Forgotten
GOLD Site Supporter
If it lights you have + 12 volts going to ground somewhere. Could be in a light socket. Any tail lights dim or not working? Could be a flasher unit shorted internally.
 
jwstewar

jwstewar

Active member
Thanks Muley, there were some, but he replaced the bulbs and fixed those. We are thinking maybe somewhere with the aftermarket radio and the amp and subs that he pulled out. We sent him a msg asking about why those are missing since they were explicitly mentioned in the ad.
 
T

the old trucker

New member
How about tying in a light between the battery cable & the terminal. Then pull out one fuse at a time. If the light goes out wouldn't that circuit be the one causing the trouble :ermm::unsure:
 
T

the old trucker

New member
I would pull each & every fuse, circuit breaker & relay. My buddy thinks it might be a bad alternator. He said to disconnect the power going to the alternator & try it. That would eliminate the alt. Be sure to check all ground wires, even if you loosen it & re tighten it. I'm sure someone here can straighten this problem out pretty easily...
 
Snowtrac Nome

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
ok on the delcotron alternator there should be a red wire that goes to the alternator light and than to positive this lead flashes the fields to begin charging check to see if some one has looped it over to the positive termanal it should go to switched power for a quick test un plug the regulator see if the test light goes out
 
B

bczoom

Super Moderator
Staff member
GOLD Site Supporter
Instead of a light bulb, wouldn't it be best to stick an ammeter in there and see what the draw is? That may help point in the right direction.

Aftermarket stereos and amps almost always seem to be the culprit so even though he pulled it out, make sure the wiring is back to where it would have been before the aftermarket "stuff". Also, was one or more new hot wires pulled for the stereo? (depending on the amp in particular, OEM wiring may have been inadequate and a new wire capable of handling more amps would have been run). If that's the case, find where it is being pulled from and disconnect it on that side as well. I've seen more then one crappy wire pull where the insulation was worn off from rubbing on something. Normally, between the firewall and under the dash.
 
T

the old trucker

New member
bczoom said:
Instead of a light bulb, wouldn't it be best to stick an ammeter in there and see what the draw is? That may help point in the right direction.

Aftermarket stereos and amps almost always seem to be the culprit so even though he pulled it out, make sure the wiring is back to where it would have been before the aftermarket "stuff". Also, was one or more new hot wires pulled for the stereo? (depending on the amp in particular, OEM wiring may have been inadequate and a new wire capable of handling more amps would have been run). If that's the case, find where it is being pulled from and disconnect it on that side as well. I've seen more then one crappy wire pull where the insulation was worn off from rubbing on something. Normally, between the firewall and under the dash.
Click to expand...


Another thing to think about Vettes are fiberglass with a metal chassis. Back 35 yrs ago I hooked onto a 48' trailer. When I plugged in the light cord...Poof... everything went black. A dead short, now find me. The mechanic hooked up the old welder to the tail light wire & said watch for smoke. Sure enough we found the problem, tucked up in a corner that you couldn't see.
 
Snowtrac Nome

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
2 things to remember vetts are fiberglass it dosn't take much for them to burn to the ground dont use the welder trickonce you have setteled on the fact you have a true draw than your next course of action will be invest in a short finder and 40 amp auto reset breaker you can follow the wire till the breaker trips than wait till it resets if you are cheap like me you can use a compass the arrow will point in the direction of the short. i know you have pulled the fuses have you pulled your breakers electric door locks and windows can be some of your biggest problems when the relays stick also if all cut wires from the sound system are not properly terminated your car may burn down
 
B

bczoom

Super Moderator
Staff member
GOLD Site Supporter
dds said:
if you are cheap like me you can use a compass the arrow will point in the direction of the short.
Click to expand...
Not familiar with this one. If nobody minds the sidebar in this thread (unless you want to start a new thread), can you tell us more?
 
jwstewar

jwstewar

Active member
Looking for something else, I realized I didn't post the cause of the short. There was a short in the emergency flasher switch. He replaced the switch and the short was gone and the battery quit draining.
 
M

mla2ofus

Well-known member
GOLD Site Supporter
dds said:
your next course of action will be invest in a short finder and 40 amp auto reset breaker you can follow the wire till the breaker trips than wait till it resets if you are cheap like me you can use a compass the arrow will point in the direction of the short.
Click to expand...

A heavy duty turn signal flasher works for this and you don't have to wait for it to reset. I hadn't heard about the compass trick. I was taught to use an inductive ammeter. Something to remember.
Mike
 
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