Computer Current Draw with Car Off

[Dont Panic]

Hi,

I have another question for the tech gurus.  My battery will slowly die if the car is not started for a couple of weeks.  I have no current draw, other than the computer which is pulling 110mA.  Is this the normal draw for the computer?

Thanks,
Devon

[Scott87]

Sounds like you have something drawing more than it should.  I am no expert but have a nice little face tube link for you.
 http://www.youtube.com/watch?v=KF1gijj03_0&feature=g-vrec&context=G22afde6RVAAAAAAAABw

The movie mentions that the draw should be no more than 55ma. 

You have an aftermarket stereo?  If so then that would be the first place to look.  Or start unplugging relays and see if that cuts down on the draw?
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[Steve Wood]

is that right after you connect your meter in series with the cable, or ten minutes or so later.

It depends on alarms, radio, ecm, etc, but I would think it should be closer to 50 ma after a bit of time has passed.

Going down in a couple of weeks sounds more like a battery with a weak cell to me-assuming the delay fan relay has been unplugged so it cannot suddenly wake up and run the fan for a bit

[Steve Wood]

by the way, I am not a guru....I sometimes play one on the net tho....otherwi se you would find me at Tim Hortons eating donuts

[daveismissing]

Ouch Steve

remembering-
This is a Tbird and not a GM so body drains may be a bit different.
15-150 ma longterm doesn't sound unreasonable.
I'm not an expert but I go to Tim Hortons- cuz you need 3 Daves to make a GN Quorum.



clock in the car? body computer? anything not switched -alky, scanmaster....

[Scott87]

Tim Hortons, I love that place.  I swear they put crack in the coffee it is,  so freaking good.

Too bad there isn't one local to me.  :-[

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[SuperSix]

My 87 T sits for over a month at a time between getting started - and the battery is fine.. Odd..

[Scott87]

Long as draw is low and you have a good battery you can leave it for long periods like that.

Anything longer probably best to put a tender on it.

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[daveismissing]

My seat of the pants calc is that after two weeks at 100ma you have used about half the capacity of a typical car battery. I'd start to worry about starting after that so disconnect  for any longer periods?

[daveismissing]

This has some draw numbers and look period correct-ish.

http://flashoffroad.com/electrical/CurrentDrain/currentdrain.pdf

[Steve Wood]

just remember to wait a minute or so to read the meter so the initial surge has settled down

[Dont Panic]

Thanks for the replies.  I did not wait much time when I checked it.  I will check again and wait a few minutes.

The 110 mA was the draw from the engine wiring harness alone.  The engine harness is separate from the car harness on this car.  The amount of draw when I disconnect the fuse going to the computer is low to nill.  I can`t remember exactly what it was, but next to nothing.  I would think that the computer would be using a few mA to maintain power to the chip, but that should be it.  Is there anything else in the engine bay that requires power with the key off?

Maybe I have a short somewhere.  I saw the Eric The Car Guy video the other week.  It lead to me checking this.  Unfortunately I have an entire engine harness to look through.  I will need to get one of those current testers (used in the video) and try to find the current draw with the key off.

This draw might also be related to my low BLM issue.

[Steve Wood]

I would not think so, but, a lot of stuff I have thought has turned out to be less than true!

Alarm system and radio memory are the normal culprits.  Hard to have a short that weak, I would believe

What is this engine in?

[Dont Panic]

It is in an 87 Thunderbird Turbocoupe.  There are no aftermarket stereos, or alarms.  There is next to no draw when I disconnect the ecm fuse.

[ULYCYC]

Borrow another known good ecm and see if it still has the same high draw.  I would do this first.