Unidentified battery drain
#1
Unidentified battery drain
To anyone that can help:
I have an unidientified battery drain issue with our '02 Blazer. I've unplugged the underhood light, disconnected the negative cable and put a test light between the cable end and terminal on the battery. I then proceeded to pull every fuse in the underhood fuseblock as well as the end-of-dash fuseblock one by one and the light never went out. Next I pulled off the front passenger side tire and disconnected the wires from the starter one by one hoping for an indication of where the problem was. The only problem I found is that the light never went out. Has anybody had this same problem and if so where did you find the source of the drain? Any help or ideas would be appreciated.
I have an unidientified battery drain issue with our '02 Blazer. I've unplugged the underhood light, disconnected the negative cable and put a test light between the cable end and terminal on the battery. I then proceeded to pull every fuse in the underhood fuseblock as well as the end-of-dash fuseblock one by one and the light never went out. Next I pulled off the front passenger side tire and disconnected the wires from the starter one by one hoping for an indication of where the problem was. The only problem I found is that the light never went out. Has anybody had this same problem and if so where did you find the source of the drain? Any help or ideas would be appreciated.
#2
RE: Unidentified battery drain
If you are sure that you pulled ALL of the fuses AND CIRCUIT BREAKERS out, then the next step is to start unhooking the battery cable connections (like you did with the starter)....next I would pull the battery cable off of the stud on the alternator. Then the battery cable connections at the fuse block or a wiring junction block if it has one. But you should be doing this test with an ammeter, not a test light. There is always going to be SOME draw on the battery, the spec on this truck should be no more than 25 mA.(.025A), but even that small of a draw will still light a test light (very dim, but still lit).
#3
RE: Unidentified battery drain
Thanks for the tips, I'll check those other places as well. Just an FYI, I started the test using my mulitester but I found that the test light was easier to see from a distance. The drain is around 12V so I used the brightness of the light at that voltage as a reference when watching for it to either go out or dim considerably. Thanks again for the info.
#4
RE: Unidentified battery drain
The drain is around 12V
#5
RE: Unidentified battery drain
That's the kind of explanation I 've been waiting for! Even a lot of manuals are vague when it comes to explaining why you must do something a particular way. I like to know why I'm doing or not doing something as opposed to "That's just how you do it". I've been using the "My buddy's dad's a mechanic and he said to do it that way" method, obviously it hasn't worked.
#6
RE: Unidentified battery drain
If you follow those procedures it will at least make sure you aren't chasing a problem that doesn't exist. If you don't make sure the BCM goes to sleep,you won't get an accurate reading. Be sure to repost your results.
#7
RE: Unidentified battery drain
After a few months without any luck in finding the problem, I finally took it to an auto electric shop. The mechanic told me that the Transfer Case Control Module needed to be replaced. He said that the TCCM wasn't the cause of the problem but that it was the effect and the problem was further upstream from the TCCM and replacing it would help him narrow it down. I haven'treplacedit yet due to a lack of funds, but I did find that when the TCCM is disconnected from the wiring harness, the drain on the battery is less than when it is connected. Any ideas as to what could be drawing power from the battery? Thanks in advance for the help.
#8
RE: Unidentified battery drain
NM I started my own post, I realized I was hijacking this one, sorry!
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azembdriver
2nd Generation S-series (1995-2005) Tech
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08-01-2008 03:06 PM