1969 C 10 dead battery

[697498chevy]

Four year old battery was dead last week , no click , lights , nothing . Put a good battery in and now it's dead too . Guess I have something killing the battery . Anyone have an easy way to find out what ? Thanks !

[72c20customcamper]

Mine was the alternator. If the diode goes bad it will draw juice . I used a multimeter to check the draw and when I pulled the wire going to the alternator the draw stopped .

[tutone]

Divide and conquer.
You have established that you have drain.
Electricity in 12v form is easy enough but what you are going to do will be time consuming.
1. Get familiar with your fuse panel
2. Make sure that your ignition switch is good.
Check each circuit (left side of fuse) for 12v with a 12v test ligh
Without the ignition switch in the on or accessory position,
look at each label. I think courtesy lights are hot and maybe cigar
lighter. The rest should be dead without the switch on.
Someone correct me if I am missing one.
There is a switched 12v male spade terminal about in the
Middle that is powered only when ign switch is on.
3. Now take the fuses out of the courtesy and cigarette lighter and make sure they are good. Before removing each, hook your test light on the right side to make sure they arent passing power. If you have your interior light on, it will be.
4. Everything that is in the panel with the key on will have power on the left and right side of the fuse. I believe you are looking for a light that wont shut off.
Also check and make sure your horn relay is not actvated and your horn doesn't work.
Alternator output should be checked as well
Good luck.

[RustyPile]

When doing any electrical work, your best tool is a complete wiring diagram for the vehicle you're working on.. Wiring diagrams can be downloaded and printed from the ELECTRICAL forum on this site.

Quick and dirty way to locate source of draw... Install a fully charged battery. Disconnect either battery cable at the battery. Using a 12V test light, connect one end of it to the battery post, and the other end to the disconnected cable.. If you have a draw, the test light should come on.. Start pulling the fuses, one at a time.. Doesn't matter which fuse is pulled first. After each fuse is pulled, look at the test light.. When you pull the fuse of the circuit having the draw, the light will go out.. Check all items on that circuit.. The two most common culprits have already been mentioned.

[697498chevy]

Thanks guys . Bought a multimeter today , trying to figure out how to use it . Plan to charge one battery and pull this old truck in my shop . My truck has a voltage regulator next to the radiator . Guess that could be bad ? Thanks again !

[Ironangel]

Originally Posted by RustyPile

When doing any electrical work, your best tool is a complete wiring diagram for the vehicle you're working on.. Wiring diagrams can be downloaded and printed from the ELECTRICAL forum on this site.

Quick and dirty way to locate source of draw... Install a fully charged battery. Disconnect either battery cable at the battery. Using a 12V test light, connect one end of it to the battery post, and the other end to the disconnected cable.. If you have a draw, the test light should come on.. Start pulling the fuses, one at a time.. Doesn't matter which fuse is pulled first. After each fuse is pulled, look at the test light.. When you pull the fuse of the circuit having the draw, the light will go out.. Check all items on that circuit.. The two most common culprits have already been mentioned.

"This is the way"

[palallin]

Finally found the culprit on my '95 Tahoe last night: the thrice-cursed vanity mirror behind the driver's side sun visor. I got in when it was dark enough and saw the faintest glow on the headliner. One pair of pliers and two clipped wires later, no more drain. Stupid feature, anyway.

[72c20customcamper]

I use a multimeter disconnect the negative cable from the battery jump the post to the strap with the meter easiest to have long leads so you can have the meter in the truck. Have your meter on the highest amp setting so you don’t burn it out . Depending on your accessories there will be a small draw my radio always draws a little . So if it’s over say 20 milliamperes you have a drain . I pull each fuse and watch the meter when it drops you found the circuit that’s drawing .

[697498chevy]

Thanks guys , have the older battery ( 7 years ) on the charger . According to my new multimeter , it's only about 9 amps . Think I need to scrap it and try charging the 4 year old battery . They were both working fine . Trying to start my old truck so I can pull it in my shop . Thanks again !

[RustyPile]

Originally Posted by 697498chevy

Thanks guys , have the older battery ( 7 years ) on the charger . According to my new multimeter , it's only about 9 amps . Think I need to scrap it and try charging the 4 year old battery . They were both working fine . Trying to start my old truck so I can pull it in my shop . Thanks again !

How did you arrive at the "9 amps"??

[697498chevy]

My new multimeter was showing 9 amps . I gave up on the older battery and put the 4 year old battery on the charger . It's only about 5 amps , so far . Thanks

[72c20customcamper]

Originally Posted by 697498chevy

My new multimeter was showing 9 amps . I gave up on the older battery and put the 4 year old battery on the charger . It's only about 5 amps , so far . Thanks

Amps or volts ?

[697498chevy]

Guess it's volts , I'm showing my ignorance . Just bought a new battery and have my truck pulled in my shop now . If I unhook the alt does that also unhook the VR ? Sorry for the dumb questions . Think I need to get a test light , that's more my speed Thanks !

[MySons68C20]

A quick check without tools is to unhook the negative cable from the battery and lightly touch it to the negative post. If you see a spark you have a drain.
It is possible your old batteries were bad or so discharged they wouldn't charge. The newer (smart) battery chargers won't charge a battery if it is under 10 volts or so.

[697498chevy]

Dumb me , I had a test light in the bottom of my tool box . With all the wires off the alt the test light's burning bright between the neg battery post and neg battery cable end . My drain must be elsewhere , but I haven't unhooked the VR . Thanks !!

[697498chevy]

Yeah I gave up on the older battery . Still have the other one on the charger , but it's only 5 volts . Thanks !!

[RustyPile]

Originally Posted by 697498chevy

Dumb me , I had a test light in the bottom of my tool box . With all the wires off the alt the test light's burning bright between the neg battery post and neg battery cable end . My drain must be elsewhere , but I haven't unhooked the VR . Thanks !!

Stop all the running around looking for a new rabbit hole, guessing at what's wrong.. Park your new multimeter, go back and read post #4..

[697498chevy]

Thanks Rusty , if I can find some help that's my plan for today .

[697498chevy]

Pulled all my fuses one by one and test light's still coming on when I touch probe to neg battery post . Working by myself , so I could've missed one . Don't think so . Also have alt and external VR disconnected . Even pulled both flashers out of the fuse box . What am I missing ? Thanks !!

[RichardJ]

>>Also have alt and external VR disconnected <<

To be clear, you unplugged the VR and the two wire connector on the Alt AND you unbolted the Bat cable on the Alt.

[RustyPile]

All the fuse pulling is done with the door open?? If you have door operated dome light, remove the bulb.....

On a side note.. In the 30 + years I was a mechanic, I can't count the number of times I've used this technique to find a drain, and conducted most of them unassisted.. Use a small hose clamp to attach the test light probe to the battery post, and clip the alligator clip to the battery cable.. It's not necessary to run back and forth probing with the test light.. Leave it connected during the "hunt"..

[body bolt]

Originally Posted by RustyPile

All the fuse pulling is done with the door open?? If you have door operated dome light, remove the bulb.....

On a side note.. In the 30 + years I was a mechanic, I can't count the number of times I've used this technique to find a drain, and conducted most of them unassisted.. Use a small hose clamp to attach the test light probe to the battery post, and clip the alligator clip to the battery cable.. It's not necessary to run back and forth probing with the test light.. Leave it connected during the "hunt"..

Don't forget to say cheese when you do this. If the current draw is enough you'll have a flash bulb.

[697498chevy]

My truck has no door operated dome light . Just pulled the ign switch and that ain't it either . I'll get my wife to help me re-check the fuses soon . Thanks !

[body bolt]

Does it have an aftermarket radio or some other accessories?

[697498chevy]

No accessories , has the O.E. AM radio . Did have a FM convertor on it years ago . Got my wife to help and rechecked everything on the fuse box . No change . Test light still stays on . Thanks !!