Battery Drain
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 1,106
Likes: 168
2018 C2 of Year Finalist
Battery Drain
I have an 88 coupe that the battery will completely drain on in about a week if the car isn't driven. The charging system works fine and as long as the car is driven or started every couple of days it won't go flat. The battery is less than a year old so I think the problem is elsewhere. I will test the battery but wonder where else I should be looking as a possible problem. I went in the garage the other night and did see the courtesy lights flashing and the "rear hatch" annunciator flashing. It didn't seem to be adjar but after reclosing it the lights went out. That is the only time I have observed that and it might be unrelated. Thanks for any input.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Originally Posted by blue67ragtop
........ I went in the garage the other night and did see the courtesy lights flashing and the "rear hatch" annunciator flashing..........
Similar solution to what davewhtt posted above:
http://www.justanswer.com/chevy/3ujs...oors-hood.html
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
just went through this with my 85 ...spent way too much unnecessary time....checking at night for lights on is the 1st and easiest...otherwise put a meter on the neg post and cable and pull fuses until the voltage drops...at least then you'll know what circuit it's in...my mistake was not knowing putting the cable and post in series with my meter makes the cts lites come on....you have to wait until they go off to check the voltage drop..(assuming they are going off..) based on your post...good luck,
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
the headlight motors not hitting their limit switch and drawing power is a common problem.
Those supply wires need to be removed from the terminal behind the battery and metered individually.
Instructor
Joined: Sep 2003
Posts: 179
Likes: 0
From: Las VEgas NV
just went through this with my 85 ...spent way too much unnecessary time....checking at night for lights on is the 1st and easiest...otherwise put a meter on the neg post and cable and pull fuses until the voltage drops...at least then you'll know what circuit it's in...my mistake was not knowing putting the cable and post in series with my meter makes the cts lites come on....you have to wait until they go off to check the voltage drop..(assuming they are going off..) based on your post...good luck,
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
You put the meter in current mode and disconnect the battery cable. Then you connect the meter between the battery and the cable. If you draw more than 10 amps you will blow the current fuse inside the meter. These are special fuses ($$$$$) and must be replaced with the correct fuse or the current function reading will be WAY off.
As playsdixie said, when you open and close the battery circuit the courtesy lights will come on, so you need to wait a minute for them to go off before reading the current.
There are some circuits that always have power on them so there is going to be a small current draw even with cars that are OK. The main ones are:
ECM (remembers error codes and BLMs),
dashboard (remembers your average mileage and trip odometer),
radio (remembers station settings and time),
electronic HVAC (remembers temperature and function settings).
As playsdixie said, when you open and close the battery circuit the courtesy lights will come on, so you need to wait a minute for them to go off before reading the current.
There are some circuits that always have power on them so there is going to be a small current draw even with cars that are OK. The main ones are:
ECM (remembers error codes and BLMs),
dashboard (remembers your average mileage and trip odometer),
radio (remembers station settings and time),
electronic HVAC (remembers temperature and function settings).
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Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 1,106
Likes: 168
2018 C2 of Year Finalist
Thanks for all the replies, some real good info here. Although I haven't located the problem yet I'm inclined to believe the door ajar switch is the culprit. When I bought the car I noticed that several of the screws were missing from the left door panel and it looked as if it may have been removed. The car also had a new battery which probably indicates the previous owner was trying to track down the same issue. Thanks again.
