Battery and shiftsymbols remains lit after turning off the ignition

Discussion in 'GM Electrical Tech' started by Ronny, May 31, 2011.

  1. Ronny

    Ronny Rockstar

    After changing 2 fuses in the underhood fusebox I encountered something strange.
    I changed the cig light fuse and the TBC battery fuse.
    i was also out with several other fuses to check if any else was blown, but all appeared ok.
    After the change I noticed that, in the instrument panel the battery symbol remained lit after I turned the ignition off, also the shiftindicators remained lit.
    Anyone, any idea?????
  2. Bigg Ron

    Bigg Ron Rockstar 100 Posts

    What was the reason you needed to change the fuses, if blown can you identify why. My first thought is a bad ground, poor grounds can lead to crazy things happening as you are describing. The ground does not have to be associated with the circuit that is causing the issue (Battery and Shift Light), check all grounds you can find for good connection.
    1 person likes this.
  3. Ronny

    Ronny Rockstar

    Hey and thanks for reply.
    I have just been out now and had a check on all the grounds I can see, but cannot see anything faulty or poor.
    The reason, I don`t actually know. I just discovered they were blown. It all started with the autoshop not getting a reading from the OBD, so I investigated a bit and found that it shares fuse with the cigarette lighter, which was blown, so I changed it and they got their reading. The TBC one might have blown when I was fiddling around in there I guess. I see now that pulling that one out, makes the battery\shiftindicator light go out......after a while actually (10-20 sec.).
    Inserting the fuse again, and the lights come on. Without the TBC fuse it appear "driver unknown" in the display when starting, cannot see any other things it does (It probably has other functions as well, hehe.).
    But it is strange that it happens just sudden........shouldn`t believe that changing the cig lighter fuse should cause anything like this, pulling it out doesn`t sort the problem either.
    Also tried to disconnect the battery "reset", but lights in the dash still there.

    ---------- Post added at 05:11 PM ---------- Previous post was at 03:53 PM ----------

    Oh well. Out a minute agor for taking my son to football practice, and yeah.....the car is officially dead. No juice left, so something is REALLY draining my battery. It`s on charger now, so I have to try it again later on and see if it will start. F***......I hate these electrical thingys :)
  4. Ronny

    Ronny Rockstar

    Well, got it running again....but problem remains.
    Did some measuring today to try to find out more, and maybe why the light symbols remain lit.
    With my multimeter I measured between the negative cables and the negative on the battery (Cables were disconnected from the battery), measuring ampere while removing fuses one by one (In the underhood fusebox).

    Initial reading 4,64 A
    Removing fuse TBC BATT (10A) (Truck Body Controller Battery Feed) reading dropped to 4,26 A.
    Removing fuse PCM B (20A) (Powertrain Control Module, Fuel Pump) reading dropped to 3,84 A, and after a very short while dropped to 1,12 A.
    Removing fuse HVAC/ECAS (10A) (Climate Control Controller) reading dropped slightly to 1,09 A.
    Removing fuse AUX PWR (20A) (Auxilliary Power Outlet - Console) reading dropped to 0,08 A.

    Well, I am far from an electrical expert, and must say that I didn`t get much wiser. I see that something is stealing power, but why should it happen suddenly just because I replaced some fuses? And why the large drop, after a short while, on the PCM B (20A) (Powertrain Control Module, Fuel Pump) fuse? Doesn`t make sense to me.

    Any electrical technical genious out there?
  5. Ronny

    Ronny Rockstar

    After going through the vehicle, checking cables and fuses and, yeah, pretty much what I could find. I didn`t find anything out of the ordinary. Problem remained, when turning off the ignition the battery lamp and shift indicator remained lit.
    Now it is duly handed over to the mechanics......hope they find it without costing me a fortune, hehe.

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