As the subject states, I need some help on a battery drain problem. The
original battery was dead and even after I was able to charge it, it would
not show and "green" in the window so it was replaced. I'm able to start
the car every time if I drive it daily, but if I leave the car for a period
of 2 days then the battery is drained to a point where I need a boost. After
that, it's fine again until I leave it un-driven for another 2-day period.
I've checked all courtesy lights, trunk and hood lights, etc. I don't know
where the drain is coming from. How do I begin to troubleshoot this
further?? GM says it could take up to 4 days to find the cause which would
cost a fortune. I thought about just buying a battery disconnect switch
just for the weekends when the car isn't driven. Other than my radio
settings, would the system not having any powere affect anything else??
Any insight into this problem would be much appreciated.
Get a cheap multimeter that can measure current. Disconnect a battery
cable and hook it in the line. If the current is more than a few
milliamperes start pulling fuses.
A similar one I ran into a while ago was a little lamp in the rear view
mirror. The guy didn't know he had one, bumped the switch and it is only
noticeable at night.
In the meantime just disconnecting a battery cable (negative wire) will be
Sounds like a dead battery to me.
(1) Internal battery drain might be caused by a shorted cell, or it might be
just a slow short.
(2) Any original battery that is older than four years is suspect.
(3) You can do standard battery tests, but you have already confirmed the
Your choice could begin by either trade the car in on a new one or spend
mega bucks and let the GM dealer troubleshoot and repair the problem.
Don't be scared that the dealer estimated "GM says it could take up to 4
days to find the cause".
I recently had a electrical problem that required 1 hour troubleshooting
time plus 1 hour repair at $ 75.00 per hour. Their diagnosis revealed that I
had a underhood 40 Amp Mega Fuse blown. Yes, I had to bite the bullet and
pay $150.00 labor bill plus parts. I did agree to let them repair my
If you choose the GM dealer, they have a everyday working knowledge and my
experience is they will try not to lolligag and let the car sit.
Being a former U. S. Air Force Radar Technician and I am impressed at the
caliber of the mechanics today and their professionalism.
You can troubleshoot this problem with a shop manual & wiring diagram & dc
multimeter & some limited rudimentary tools yourself in
your driveway with good weather.
To start with, I will save you grief and frustration of exercising your gray
matter by sharing with you some secrets of automotive electricity.
Are you ready to "How do I begin to troubleshoot this further?? ."
Hopefully you should continue to use the car like when it was new without
"I thought about just buying a battery disconnect switch just for the
weekends when the car isn't driven."
At the very least, a battery charger should be kept available until you find
1. A wiring diagram would be helpful for your benefit to follow the current
flow originating at the battery.
2. Remember, the one primary rule of troubleshooting is start at where the
problem occurs such as Discharged Battery.
3. So, start at the battery: Determine whether it is a good battery when
4. If time is a problem, Sometimes I have used a a good fully charged
5. If you have, can borrow, or purchase a DC multimeter with at least 10
Mega Ohm per volt input sensitivity:
a. Insure all doors are shut, trunk lid closed, ignition switch and ALL
accessories are OFF with key removed before proceeding.
b. Disconnect the Negative battery terminal.
c. Select, depending upon the meter, 10 Amp unfused scale.
d. Connect the meter in Series between the Negative Terminal Post and
e. Don't be alarmed if you see a reading. If nothing is wrong the
reading should range between 7 to less than 50 milliamps.
f. If the reading is higher than 1/20th of a Ampere or 50 Milliamperes,
this will confirm you have a excessive parasitic current draw.
g. Record your initial reading as a matter of latter reference. Observe
the reading with a door opened versus closed.
h. Now here is your chance to become a auto electric expert by start
pulling fuses and observing any change in the meter reading.
Remember throughout this process if a door is open, your need to
subtract your dome light draw from your meter reading.
i. While you are performing these tasks please understand Parasitic
and/or Static Current draws need to be understood.
Key off parasitic current draws includes anything that requires a
bias such as onboard computer(s) and a malfunction.
Also consider these:
entry courtesy lights operated by doors being opened and closed via
door post switches,
mercury switched gravity sensitive hood and trunk lid courtesy lights
at light socket,
If you are able to isolate the problem concerning the above, you may
have to either remove bulb(s) or disconnect wire(s)
I will understand if you decide otherwise.
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
More of a mechanical tech:
rather than a diagnostic or electrical/drivability tech. There are
classifications of techs in dealers, look at who's always doing R&R's&R's,
brakes, front end and under car. Then on the other hand, look at the techs
that are always doing the electrical spectrum of the vehicle, such as:
diagnostics, fuel control, electrical ignition, electrical in car,
There is no shame in being either, just some are more proficient or more
comfortable with one, more than the other.
Are you the reincarnation of Sam Kinnison?
If you are, you suck and go back to being dead. You were funnier before.
A two hour flat rate to locate a bad fuse?
It's so easy to start a diagnosis at the fuses, even an idiot like you could
do it. in .10. I'm sure you can, I have faith in you moron!
I've seen many of Huyndaitech's posts, he answers a lot of GM posts, so he
most likely works for a multi franchise store. He has answered more
technical questions than I've seen a lot of so called techs here answer. I'm
sure you couldn't wipe his ass in acumen!
I had *exactly* the same thing with my car. I took the battery back
to Wally-World, as they had sold me the battery a few months earlier.
They did a quick diagnostic on the battery that took 15 seconds and
got me a brand new battery.
Quid quid latine dictum sit altum videtur.
(That which is said in Latin sounds profound.)
Thanks for your replies. Here's another little test I did. My neighbour
also has an Impala so we compared current draw with a meter. Both his and
mine are drawing 1.2 A with the car off. To me that's high, but he has no
problems with his car which throws me off. Also, this car has battery run
down protection. Does that merely turn off any lights accidentally left on
or is it suppose to electrically "disconnect" the battery via relays or
whatever if the level gets too low. Overnight the voltage remains pretty
high at 11.8v but after 2 days it's about 6V.
Are you sure about that 1.2 A? That sounds way high to me. With most
multimeters meters you would have to use a 10 ampere scale
And, I think the run down protection is just an automatic way to turn off
lights. Most cars have that now.
If you are indeed drawing 1.2 Amps you could drain a battery in two days but
your neighbor would too. I will go with the bad battery and suspect that
you had the wrong scale when reading current.
That is unless when reading your neighbors car you had the hood open and
there was an underhood lamp that was on.
On second thought I think you did not leave the meter hooked up long enough
to get a good current reading. It takes several seconds - perhaps a minute
before the initial current settles down. I think that you will read over 1
ampere when first hooked up. Then after about 30 seconds to a minute it
should settle down to something less than 0.1 ampere.
Not unless there was a large draw:
That was eliminated after the meter was hooked up.
The static draw will be the static draw, unless he found a hood lamp,
removed the bulb, then the draw would have went down slowly. As the battery
located it's point surface charge.
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