Need Help

Discussion in '2005+ Mustang GT 4.6L Tech' started by TzReddy, Nov 12, 2019.

  1. TzReddy

    TzReddy forum member

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    Ok so need little help. My brother has a 2005 GT. Well he had some fan issues awhile back and bought after market fan but decided that he was going to use the #41 relay (fuel pump relay) as his on/off signal by pushing the wire in with the relay. I guess then the fuel pump fuse then blew. He replaced the fuse and the relay but now the fuel pumps are not turning on whatsoever. So I decided to try and use jumper wire and check to see if relay or possibly something else and even using a jumper wire in #41 still no signal to fuel pump. I tested fuel pump by pulling out and giving power and it works. Also there is power to the connection to top of fuel hat. It seems to just not be getting signal to turn on tho for some reason.

    I guess he messed with it more and now the car is not reading much of anything. When relay is in #41 the throttle body doesnt actuate with key forward but if use jumper wire it will. Also the computer wont recognize his SCT when plugged in and says some error #21000. I am by no means an electrician but I know basics but I am truly stumped on this one. Is it possible something wrong with fuse box? Something wrong with ECU? Just trying to help the kid out and not knowing where to start. Only other thing I know is that his battery was super dead but he charged it and should be good now. Its weird because before he messed with relays and stuff the car turned over and tried to start no problem and read the SCT last week. The fuel pump seemed to be the only issue at that time. But now basically no communication.
     
  2. Juice

    Juice forum member

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    Sorry, but he is screwed. You cannot go taping power/running jumpers on these cars. He is more than likely overloading a circuit or two. Besides blowing fuses, the computers have overcurrent protection on some power circuits. (Not in the shop manual, I found this out first hand)

    He should undo all the non-factory modifications put it all back to stock. Than he can start troubleshooting the actual issue that is remaining.
     
  3. TzReddy

    TzReddy forum member

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    How do you correct the over current protection?


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  4. 07 Boss

    07 Boss Senior Member

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    Generally the 21000 code is a computer code, not an OBD code, for system files not being configured properly. This leads me to believe the ECU or the SCT unit is bricked or corrupted somehow. I might try unhooking the battery for some time and resetting the ecu or see if the SCT needs to be updated. If that won't work I might try a new tuner with a different tune.
     
  5. TzReddy

    TzReddy forum member

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    Dont believe its SCT at all. My guess is ecu. So if he bought a new one does anything need to be done prior to putting in?
     
  6. 07 Boss

    07 Boss Senior Member

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    I believe you have to get it flashed at the dealership, but don't quote me on that.