2007 WRX TR - No electrical Power at all!
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This is a discussion on 2007 WRX TR - No electrical Power at all! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Hello Guys/Gals, Here is some back story. I was working on changing my bulbs for my car as they went ...

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    Exclamation 2007 WRX TR - No electrical Power at all!

    Hello Guys/Gals,

    Here is some back story. I was working on changing my bulbs for my car as they went out. When putting the battery back in place my buddy accidentally hit the positive terminal with the metal part of the AC hose line. Small spark came up then when we tried to check for power there was nothing.

    What I have done:

    1. tested battery on another car (its good)
    2. checked all of the grounds to the car (they are good, even did some sanding and cleaning to make sure)
    3. Checked every single fuse! (none are popped *under hood and in car*)
    4. Bigger fuses 50amp 120amp are also good. (I used a multimeter to check and make sure ground connection is still occurring.
    5. Used multimeter to test ground spots to the negative battery terminal harness everything shows as current passing.

    I feel stumped guys. I feel like its probably the 120 AMP fuse but it looks like its in good condition! I have to get the fuse ordered from the dealership if all fails.

    Any of you guys know where to begin? I have done a few searches but cant seem to find a solid lead. Any help would be greatly appreciated.

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    Registered User Obeisance's Avatar
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    You say no electrical power: this means no response to the key, no lights when you open doors or trunk. That is not a good sign.

    I'm a bit confused about the spark process: you mean that your friend was lowering the battery into its tray with the negative battery lead attached (thus allowing for current/spark to flow somehow through the AC line)?

    As unlikely as it may be, do you suppose that you somehow short circuited through the ECU, thus frying it? Can you check resistance between the path that you got a short circuit through? (+Batt to -Batt - should be open.. and AC hose metal to -Batt - this hose has a metal connection to the condenser, right, and that should be grounded to the car via the radiator support, with no possible path to the ECU, excepting through a sensor)
    David - '05 WRX

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    Moderator Donkey's Avatar
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    Pull the fuse and test it for continuity. Hopefully the ECU didn't get fried.


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    The battery was in place. He was ratcheting the positive terminal in place and hit the hose to the condenser. That's how the spark came alone I took the ecu out and looked at the board nothing's fried.

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    Fuse has continuity

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    Registered User Obeisance's Avatar
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    can you check the voltage of pin 16 on your OBD port vs ground? this should read V Batt, and indicate that potential is making it away from the battery, and (i suspect) safely through the ECU.

    edit: pin 16 is a corner pin, on the narrow, upper part of the port nearest the drivers side: Clock pod mod with Subarb Select Monitor ECU polling and Arduino
    Last edited by Obeisance; 08-02-2014 at 02:52 PM.
    David - '05 WRX

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    It reads 0

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    Registered User Obeisance's Avatar
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    hmmm.. well, in order to isolate the bad component, I think that I would work from where connection is good, following wires to where the connection is finally missing. Starting on both the positive battery lead, and following through the thick parts of the wiring harness making sure continuity is good, and doing the same for the negative lead (in spite of the chassis ground continuity, there may be some other obstructed path).

    I still cannot believe that you could fry the ecu in the way that you described a short. Do you know if there's a good way to check for the functionality of the ecu? (my quick search turned up nothing, but maybe you can check for power to the ecu, or plug it in and check for power coming out of it on certain pins after looking up a wiring diagram)
    David - '05 WRX

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    Registered User Obeisance's Avatar
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    I found an interesting thread about troubleshooting short circuits which fry the ecu:
    Short keeps frying ECUs - NASIOC

    I'm still not sure if this is relevant to you since your power does not seem to leave the battery.
    David - '05 WRX

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    Taking a break for a bit I stayed up till 4:00 AM diagnosing. Woke up this morning early continue then made this post when I got stumped. I need a nap. For now I think its the ECU. I found that there was a broken ground terminal from the fuse box so I replaced that. It still had continuity before but now I have made sure that everything is actually good. I was unable to find any kind of other bad grounding spots spent a while with a multimeter doing a bit of testing.

    I wonder if that possibly had anything to do with possible ECU blowing. I still am unsure. If I pull the ECU out what should I inspect? I dont think it got damaged it did not smell burnt.

  12. #11
    Moderator Donkey's Avatar
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    The ECU is an incredibly sensitive unit. You are not going to necessarily find something fried or burnt. If you understand the concept of why static electricity is bad for sensitive electronics (laptops/desktops/pads/phones/ect..) then you might get how a simple arc can render them useless. But it could also be an issue with the ignition relay or immobilizer as well. I would find a copy of the FSM to get the wiring pin-outs.
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    Okay. So would it be the relay? It seems like the power would not make it there. No spark on the battery when I pop the pos back in place. I'm just kind of upset that this could happen from a small arc would cause that to happen to the ecu. My old Hondas had a ecu fuse. Wish we had one hahah.

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    Moderator Donkey's Avatar
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    Quote Originally Posted by shintoxica View Post
    Okay. So would it be the relay?
    Is the car in front of me? I'm diagnosing a car over the interweb. FYI-you always hook up the neg battery cable last and always remove it first.
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    Sorry guy, cool your jets. I am i am just asking a question out of context that it feels like it would not be it.

    Thanks for the advicem I know this rule of thumb I was not presently in front of the bay watching him as he did this. It was a simple mistake and I am just trying to get clues on the net for what else to look for.

    so far no progress nothing looks out of ordinary im starting to give up and looking to get it fixed professionally

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    Moderator Donkey's Avatar
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    Not trying to be a jerk,but how do you expect anyone to know if it's the relay or not with you actually testing it yes? Your asking questions that nobody can answer. Your at a point where you need to diagnosing things on a physical level.
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