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Battery Drain/Relay problem

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by blaik, May 21, 2009.

  1. blaik

    blaik New Member

    Okay folks, I've been working on my 97 GMC K1500 1/4 4WD suburban for a while now and I've battled my way through bad plugs, bad batteries, new starter, retapping a JB welded hole for the radiator line coming out the top of my intake manifold, replacing the alternator, replacing u-joint, and lastly replacing the seal on the rear power transfer shaft. All of this since about...oh January.

    I love my 'burb and I refuse to give up on it, nor do I want to take it in, but this one's got me stumped. Had to replace the battery last November, and then it starts going dead on me a month or so ago. I took it in, had it tested, it checks out 100%, but I'm still dropping below cranking amps overnight. so I start tracing the dang thing down. At first thought it was my radio, then the CD player (they're separate on my model) so I had them both disconnected and I'm still getting a draw. Every time I reconnect my neg cable I can hear a faint buzz then a click like a relay. This afternoon I was able to chase it down to where I think it is. Under the dash, to the right of the steering column is a small metal box with a plug on the bottom of it and what looks like a relay on the side. I don't know what its called, what it does, or how to get it out of there, but it sounds like that's where it's coming from. I'll try getting a pic of it tomorrow in better light and puttin it up here.

    Does anyone have any idea what this is, what it does, and how to get it out? I have the owner's manual, a haynes manual, and you guys, and so far the first two haven't been much help to me on this one. Hoping someone out there does know. Thanks!
     
  2. Springthing

    Springthing Epic Member 5+ Years 1000 Posts

    I won't be of much help but I'm sure a picture will help those that might be able to help.

    Good luck with tracking down this electrical gremlin. Hopefully someone here will be able to give you a hand.
     
  3. L0sts0ul

    L0sts0ul Rockstar 100 Posts

    if you can get ahold of a DC Clamp on Ammeter, you can actually tell exactly how much current is being drawn when your truck is off, and that might help to give you an idea as to what kinda system you are looking for,

    you can also do this using a Voltmeter, however its a little more math intensive.

    I can help you with that if youlike.
     
  4. blaik

    blaik New Member

    Okay, so I went back and did some more hunting on it. I found 3 fuses that when plugged in will generate the buzz/click I'm getting. one is the fuse for the courtesy lights, the next is the transfer case fuse, and the third is the radio battery fuse. Based on the wiring diagrams I have in my Haynes manual, the one common point all 3 of those systems might have is the Vehicle Control Module (VCM) but I'm not 100% on that. Does anyone know what might tie all three of those together, and if it is the VCM, where is the VCM located? I can't find mention of it anywhere except in the wiring diagram.

    and to springthing and L0sts0ul, thanks for the advice and encouragement!

    EDIT: Okay, here's some more info. Just pulled out the multimeter and did some checking. With those three fuses unplugged I'm just under 50 mA draw on the battery. With the transfer case fuse plugged in I bump up to 70 mA draw. Took that out and put the ctsy lights fuse in and it jumped to 150 mA draw (and yes I made sure the doors were shut, after replacing the fuse in my MM, stupid me). took that one out and put the radio battery fuse in, and I have no idea how much that's drawing because it instantly blows the 315 mA fuse for my MM every time. So based on those measurements I'm jumping from ~50 mA draw to 530 mA draw with those 3 fuses plugged in. I'm guessing they would draw a bit more than that, I'd be willing to go even as far as 75 mA, maybe 80 mA under normal conditions, but I'm looking at 5-7 times that amount of draw, but the problem is...where do they all connect? or do I truly have a situation where three independent systems have truly gone haywire on their own at the same time?
     
    Last edited: May 23, 2009
  5. blaik

    blaik New Member

    Was just going to try again and see if anyone knew where the three systems I listed previously would all come together?
     
  6. L0sts0ul

    L0sts0ul Rockstar 100 Posts

    im not sure if this has been answered before but do you have a amp factory or otherwise?

    and did you check the stupid personal map lights in the back? I caught my kids a few times playiung with them.
     
  7. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Cigarette lighters can be trouble, as well as the glove box light.
     
  8. boduke5051

    boduke5051 Member

    just a suggestion to narrow it down, I would try to pull the ctsy lamp fuse since it seems to be the biggest draw, let it sit overnight, then see if it'll start in the morning. if it does, then you know you've got a problem in that circuit somewhere. if not, I'd move on to the transfer case fuse. I'd expect a constant draw from the radio circuit to keep the memory. the other 2, I can't think of any reason why they should have a draw if not actually in use, but I'm also used to working on a lot older vehicles, so I may be missing something. if you're able to narrow it down to one of those circuits, then I'd start physically chasing wires to see if you can find any chafing or other damage that might be causing a short. if you're not able to narrow it down any further than those 3, then I would guess something in either the VCM itself, or possibly in some other wiring for the VCM and in either case, I'm out of suggestions.

    Good Luck, hope you get somewhere with it.
     

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