150mA drain on battery, killing batteries and can't trace

Discussion in '2005+ Mustang GT 4.6L Tech' started by Macman45, Oct 3, 2022.

  1. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    my 09 is having a parasitic drain, and if not left on the trickle, battery is so dead none of my chargers can revive. REALLY dead. Did the ammeter in line and seeing a solid 150mA drain with everything off and powered down. I was hoping for about 20mA

    I then went and pulled EVERY fuse in the box, no change. Even #67 which powers the SJB.

    Next, I removed each of the 4 connectors under the fuse box, and sure enough, the black one, C1035a, when removed, drain drops to zero. Unsure why pulling EVERY fuse does not reveal that, but I have traced to that. Still no idea which circuit in that connector.

    For reference: I have Shaker 500, no 1000 or trunk subs, removing the radio fuse does nothing...

    IMG_7585.JPG
     
  2. Laga

    Laga Senior Member

    853
    421
    Did you follow the procedure from the shop manual? It REALLY has to be followed EXACTLY as written . I just went through a drain that turned out to be LED map lights in overhead console.

    1. Make sure the bussed electrical center (BEC) and smart junction box (SJB) are accessible without turning on the interior or the underhood lights.

    2. Drive the vehicle at least 5 minutes and over 48 km/h (30 mph) to turn on and activate the vehicle systems.

    3. Allow the vehicle to sit with the key off for at least 40 minutes to allow the modules to time out/power down.

    4. Connect a fused (10A) jumper wire between the negative battery cable and the negative battery post to prevent the modules from resetting and to catch capacitive drains.

    5. Disconnect the negative battery cable from the negative battery post without breaking the connection of the jumper wire.

    6. NOTE: It is very important that continuity is not broken between the negative battery cable and the negative battery post when connecting the meter. If this happens, the entire procedure must be repeated.

    Connect the battery tester between the negative battery cable and the post. The meter must be capable of reading milliamps and should have a 10 amp capability.

    7. NOTE: If the meter settings need to be switched or the test leads need to be moved to another jack, the jumper wire must be reinstalled to avoid breaking continuity.

    Remove the jumper wire.

    8. NOTE: Amperage draw varies from vehicle to vehicle depending on the equipment package. Compare to a similar vehicle for reference.

    NOTE: No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.

    Note the amperage draw.

    9. If the draw if found to be excessive, remove the fuses from the SJB one at a time and note the current reading. Do not reinstall the fuses until you have finished testing. To properly isolate each of the circuits, all of the fuses may need to be removed and install one fuse, note the amperage draw, then remove the fuse and install the next fuse, until all of the circuits are checked. When the current level drops to an acceptable level after removing a fuse, the circuit containing the excessive draw has been located.

    10. If the current draw is still excessive, remove the fuses from the BEC one at a time and note the current draw. Do not reinstall the fuses until you have finished testing. To properly isolate each of the circuits, all of the fuses may need to be removed and install one fuse, note the amperage draw, then remove the fuse and install the next fuse, until all of the circuits are checked. When the current level drops to an acceptable level after removing a fuse, the circuit containing the excessive draw has been located.

    11. Check the Wiring Diagrams for any circuits that run from the battery without passing through the BEC/SJB. If the current draw is still excessive, disconnect these circuits until the draw is found. Also, disconnect the generator electrical connections if the draw can not be located. The generator may be internally shorted, causing the current drain.

    I copied the above instructions from a different Mustang forum, but they are from the service manual.
     
  3. Juice

    Juice forum member

    4,353
    1,718
    How long does you car sit between uses?
    Are you sure your battery is fully charged?

    I have learned sine not using mine daily, that the battery will get drained and not fully recharge with my limited use. (But still start the car fine)
    I have started seeing my aftermarket guages 'forget' my color setting and revert to default blue after starting the car. I now keep a battery tender on it, guages do not lose my setting when the battery is fully charged. I dont believe I have excessive draw. It takes 6-8 weeks of non use to drain a fully charged battery to no start point in mine. Thats the reason I asked those 2 Q's.
     
  4. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    It does sit a lot but normally on a tender. Sometimes I forget. I am now starting with a fresh and charged battery, 12.6ish. Mine will go no
    Start in under a month. But the fact I’m seeing over triple the max recommended drain means I do have an issue.

    I will repeat the test with the jumper wire. I was letting the meter re-establish the connection that’s on me.

    And disconnecting that one plug removes the drain so I don’t think it’s internal to the alternator (my hope) but something coming off the BEC
     
  5. Juice

    Juice forum member

    4,353
    1,718
    I have seen a bad voltage regulator drain battery.
    Unplug the small connector on the alternator and recheck the draw.
     
  6. redfirepearlgt

    redfirepearlgt forum member

    2,433
    213
    To begin with there are more than just the SJB fed through C1035A. At a quick glance/skim of the prints the following fuses are on this connector F62 F45 F65 F61 F44 F47 F41 F42 F54 F64 F68 F59 F63.

    I will work with you if you wish via PM. First and foremost however REMOVE ANY AND ALL LED LAMPS YOU HAVE INSTALLED IN THE CAR. THIS INCLUDES SIDE MARKERS, CONSOLE LIGHTS, A.K.A - ANY LAMP THAT WAS NOT FACTORY SPEC'D. Then check your current after 1 hour and see if the 150mA has not dropped to about 35mA.

    Good luck.
     
    Macman45 likes this.
  7. Juice

    Juice forum member

    4,353
    1,718
    I have ALL but one conventional bulb left. Did not get an LED for the trunk light.
     
  8. Pentalab

    Pentalab forum member

    4,887
    899
    IOW, you installed LEDS everywhere.... except the trunk.
     
  9. redfirepearlgt

    redfirepearlgt forum member

    2,433
    213
    If aftermarket LED's work for someone great. More than once on this site and others LED's have been a source of parasitic current drain. Doesn't mean it always is. Remove them and see if the current drain drops to less than 75mA after 1 hour with the car completely off. If the problem still persists its on to other issues...OR start pulling the fuses I listed since OP said the current drain goes away if he pulls C1035A. It's a process of elimination to narrow down to the source of the problem. Its not the answer to the problem...but maybe it is.
     
    Macman45 likes this.
  10. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    Zero LED’s on the car. C1035a IS causing the drain. No need to look elsewhere if disconnecting that plug stops the draw…..
     
    redfirepearlgt likes this.
  11. redfirepearlgt

    redfirepearlgt forum member

    2,433
    213
    then pm me with the fuse that causes the current to drop back down. observe the procedure that laga provided.
     
  12. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    Roger that. I am repeating with the proper procedure because right now, no fuse drops it down that’s the problem. Procedure did state REMOVE all
    Fuses and add one at a time or maybe add and subtract so there’s only ONE on the board at a time. I guess it’s finding another path to ground via another fuse that’s why all must be removed?
     
  13. 05roush0090

    05roush0090 forum member

    351
    0
    I hope you figure your issue out. I’ve been trying to defeat a similar drain. For me if I pull under hood fuse #56 (radio), #59, #67 (both SJB) my draw drops dramatically. So I swapped my stock shaker 500 for the Dynavin N8 and got a used SJB with same model# on it as my stock unit and I still have the same draw:Chainsaw:
     
  14. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    dang. Did it take all 3 fuses pulled at once to eliminate the drain?
     
  15. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    Wow just repeated with the above instructions and your 3 fuses together, drain drops to under 20mA. Around 15mA. So 10% of what it was. Perfect. Same boat as you for why it’s doing that…
     
  16. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    Alright re-adding the radio, #56, doesn’t cause much of an up tic. 25mA. Fine by me. BUT adding in EITHER of #59 or #67 shoots us back to the 150mA. So it’s something in the SJB. Doesn’t require both fuses, either do it. Any thoughts guys?
     
  17. Laga

    Laga Senior Member

    853
    421
    The procedure I posted above HAS to be followed EXACTLY as posted.
    After driving for 10 minutes, park the car, open the doors and close door latches with a screwdriver. This allows access to SJB without activating ECM. Do the same if you have under hood light. Then wait 1hour. When you pull fuses, do not reinstall until all are removed. Here is a video. Follow it exactly. If you don’t, your test is not valid and a waste of time.
     
    09brian0 and redfirepearlgt like this.
  18. Macman45

    Macman45 Resident Geriatric

    1,359
    135
    That’s right. But my problem is now inside the SJB. It’s looking like an internal issue in the module. Bummer.
    Additionally, my dome light isn’t coming on when opening the doors but the windows dip so it’s not a jam switch issue.
     
  19. redfirepearlgt

    redfirepearlgt forum member

    2,433
    213
    ^^^ Verify F10 (5A) fuse on the SJB. That feeds the console lights. The SJB also has to be reprogrammed to work on the CANBUS with the other devices. A friend locally lost his due to water intrusion and tried to just replace it with a new one. Was not able to complete the task without it being commissioned at a local shop. So you may wish to put the original back in if you have not already.
     
  20. 05roush0090

    05roush0090 forum member

    351
    0
    yes for me. I honestly thought replacing the shaker 500 with the Dynavin radio it would have taken the draw that fuse 56 was causing but it did not. I think I need a new SJB. The used one I bought did not fix the issue so it must have same thing going on.
     
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.