...Roger...

There seems to have been a lot of battery drain issues lately.Thought I would write down this fairly easy way to check for battery drain and share it.All you need is an inexpensive 12 volt test light and a short piece of wire. A test light like this one will be very useful for other 12 volt electrical issues. Use a bulb type of test light for this test procedure not an LED type.

If you have a C3 and “DO NOT” have delayed courtesy lights and your courtesy lights work this is “my” way to check for battery drain Put both windows down and make sure everything is turned off. Disconnect the negative battery cable and put your 12-volt test light between the (-) battery terminal and the (-) battery cable. Here is a picture to help. With the driver’s door open the test light should be lit. Make sure everything is turned off and close the driver’s door. Wait several minutes (clock step). If the test light stays out completely (no low glow) you have no battery drain.
If the test light is on or even a low glow you have a drain on your battery. (bright bulb is heavy drain ,dim bulb is low drain) First thing I do is push on the doors and watch test light then lean in through the window and push on things with lights like the glove box door, visor light, map lights and the rear center compartment and watch to see if test light flickers or goes out if so you have found your drain. Second thing I do is open the drivers door and remove the courtesy light fuse, if the test light goes out then the drain is in the courtesy light circuit. If the light remains lit continue to remove fuses until the light goes out and that will be the circuit with the drain. If the test light doesn’t go out then the drain is in a circuit not protected by the fuse box.

“Clock step” Info----clocks can be a pain.
Above when you closed the door if the test light went out but came back on shortly afterwards it’s the clock trying to wind and its drawing too much. Disconnect the power to the clock and retest.

If you determine your draw is in the courtesy light circuit disconnect the power to the clock and retest. If this doesn’t eliminate the draw you can now move on to other items on the courtesy light circuit.

OVERNIGHT CLOCK TEST-I use this alot on mechanical clocks on cars that have intermittent power drains.Leave test light hooked up as above and let clock continue to run through the test light all night.If you come out in the morning and the light is off then the clock is in good shape.If the light is on the clock will have stopped and you should have the clock checked or replace it.
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If you have a 77-82 C3 and “HAVE” and have delayed courtesy lights and they work and turn off after 30 seconds this is “my” way to check for battery drain. Put both windows down and make sure everything is turned off. Disconnect the negative battery cable and put your 12-volt test light between the (-) battery terminal and the (-) battery cable. Here is a picture to help. With the driver’s door open the test light should be lit. Make sure everything is turned off and close the driver’s door. The test light should still be lit because the delay relay is engaged. Now (and lets call this the “jumper” step) lean in through the driver’s window with a small piece of wire to use as a jumper (white wire in the pic.) connect the jumper from the (-) battery terminal to the (-) battery cable. Your courtesy lights will come on and the test light will go out --wait for your courtesy lights to go off --remove the jumper lead. Wait several minutes (clock step). If the test light stays out you have no battery drain. If the test light comes back on you have a drain on your battery. Just to be sure do the “jumper” step again to make sure the delay relay was off. If the test light came on again open the driver’s door and remove the courtesy light fuse, if the test light goes out then the drain is in the courtesy light circuit. If the light remains on continue to remove fuses until the light goes out and that will be the circuit with the drain. If the test light doesn’t go out then the drain is in a circuit not protected by the fuse box.

“Clock step” Info----clocks can be a pain. Above after you removed the jumper the test light went out but came back on shortly afterwards it’s probably the clock trying to wind and it’s drawing too much (plus it reset the delay relay). Disconnect the power to the clock and retest as above.

Interior light delay relay –The “jumper” step turns the relay off but the relay will reset and try to turn on the interior lights at the drop of a hat causing the test light to come back on. Any draw will reset it. If you find that removing the courtesy light fuse eliminates your battery draw then the “simplest” way to continue testing is to disconnect the delay relay. In the 5 wire connector you pull off the relay are 2 white wires- connect a jumper between them. This will make your car temporarily a “non-delayed interior light system”. Now you can test using the “DO NOT” have delayed courtesy lights procedure above. If you choose not to bypass the delay relay you will have to use the “jumper” step every time you trigger the relay.


Multimeter Testing—In my opinion you don’t need the multimeter to check for battery drain down to very acceptable levels. However if you want to use one in place of the test light you need a multimeter that will take a heavy amp draw or you will smoke your meter or blow the internal fuse and you must be on the amp.setting not volt setting.

EDIT-It took awhile but I had to close up a bunch of gaping holes concerning clocks and the possibility of intermittent power draws due to sticky or dirty points.Also had to change the wording to make a delayed system easier to diagnose.

wacked

Pics dont work.

Durango_Boy

Great writeup bud. The link for the test light defaulted to a ZIP code search. Readers...just enter your ZIP and it'll go to the test light. Also, neither of your Photobucket links worked.

Everything else was spot on. Thanks for taking the time to write that.

wacked

Fixed

...Roger...

Thanks guys those links gave me fits.

SoCalErv

Photo links are working for me.

SIXFOOTER

Good one Roger, something I have been meaning to do but don't have enough of my car together to put it together.

Good candidate for a Sticky!

sperkins

Thanks for sharing. I've been fighting a drain on another old car for years. I'll give it a try.

tcl71

GREAT tip,

just made me think of a couple things....if the clock works or the radio has memory power ,will it still lite the test lite ,or is that not enough draw?

Tom

kdf1986

Thanks for the tips. I have a 72 with a dead battery in it from last weekend. I was thinking that the alternator was shorted out. This will be a good paper to do some testing with.

kdf

gq82

Nice write up....but would the clock also keep the light lit.

...Roger...

Thanks Danny- I went back to address the clock issue and ended up making it too complicated so I went back in again and rearranged.Check it out and tell me if you see anymore holes.It of course is not a complete electrical troubleshooting guide only enough to get someone started in the right direction.Thanks

A good clock mechanical or quartz and or memory on the radio will not light the test light.(providing its not an LED)

:o If anybody was trying to use the test last night and noticed it changing it was me trying to get it right.Sorry- its easier for me to do these tests than it is for me to put into words.

skeptic

Great write-up. I just found it by searching for a way to find what is draining my battery. New battery a couple weeks ago, dead today when I went to drive it.

I have a new stereo with memory (stereo is fairly new, issue was going on before) and I have a multi-meter but not a light bulb style tester. Just so I know I'm not going to blow out my multi-meter as well as what I should look for when everything is off, what would a normal amount of draw be, both with interior lights on and when everything is off? I don't have a clock if that matters.

On a possibly related note, does the stock car alarm ('81) work like newer do-it-yourself alarms and use power fluctuations (open door lights come on) as an indication of break-in? My alarm occasionally goes off for no apparent reason.

BrianTB

I just started diagnosing the same "dead after 3 days" battery problem.

Any idea what kind of current draw is acceptable?

I use a mulitimeter instead of the cicuit light and got 6.0mA when I had a radio and amp hooked up. I unhooked the amp and get about 0.1mA with just the radio still hooked up (not sure why the radio is drawing current when the car is off, problem for another day).

joewill

6 Ma is great, that is usually the clock, or aftermarket radio draw to keep its memory settings. Mine is 9 or 11 Ma, don't remember, but car sat for 6 weeks over winter and then started right up.

if your battery is dead after 3 days and have a less than 25Ma drain... then replace your battery.

Alan 71

Hi Roger,
Lot's of info.
Could you please explain again what a person should see during the test if they have a original clock (71) that works normally when the battery is hooked up.
Thanks for your effort on the post and your reply.
Regards,
Alan

toolman1981

Great info on troublshooting!!!

Mine is always "dead after 7 days".

Thank you Roger for helping others with their c3 problems.

VetteHalen

thanks. did the test above and learned i have a small draw somewhere not protected by the circuit box and big draw on the courtesy lights/horn circuit, so i removed that fuse. i'm thinking it is directly connected to my horn blowing issue (i disconnected both horns so that i could at least have courtesy lights but the big draw was still there and killed my battery). i'm guessing there's something funky in the steering column or behind the dash.

bonus question: because of the mystery low battery drain I now unplug the battery whenever the car will sit for more than a day or two... this shouldn't harm anything, right?

...Roger...

...Roger...

Hi Alan sorry for the delay to you and the others posters , I didn't see this thread pop back up plus my internet connection down south can be pretty bad some days and I just give up trying to get on CF.
Alan on your car the clock should run like normal "through" the test light, if you see the test light come on and the clock stops running the clock was trying to rewind itself and is pulling too much amperage and can't fire the solenoid in the clock to do the rewind. In most cases if you put your ear close to the clock you can hear the snap of the rewind. Hope I answered your question.