Nissan Repair: 94 nissan altima gxe computer problems, nissan altima gxe, throttle position sensor

Question
i have a 94 nissan altima gxe and i just recently replaced 2 of the main harnesses because they were burnt in a stereo accident.  the car ran fine and first but then started to idle rough, bog out when i got on the throttle, stall and idle irratically.  i ran a snap on diagnostic computer and it came up with error code 54, saying that the a/t computer circuit with the ECM is shorted or faulty.  i dont know how to fix it and i called nissan and they told me that they couldn't tell me anything without them testing it.  also, when i was testing the throttle position sensor, i heard a buzzing sound coming from the transmission when i moved the throttle.  i was wondering if you could tell me how to test the transmission computer components so i can figure out wat i have to replace.  it seems like the transmission computer isn't reading the throttle position sensor right and it's not mixing the air and fuel right.  i would really appriciate it if you could help me out.  thanks for your time.

Answer
Scott,

Yes, you guessed correctly.  The over amperage took out the transmission computer too.  The buzzing is the transmission computer cycling one or more of the servos.  I have done two cars that had that problem.  Make sure your amplifier has a really good ground connection to a clean surface and use a star washer to get a good connection and use a good gauge wire to connect it.  I would source the transmission computer at a wrecking yard to save money.  Quite expensive to purchase a rebuilt unit.  Also, check the wiring to the transmission computer.   The way automotive computers work is that they ground systems to activate them.  Now, you get the idea of why it cooked so much wire and damaged computer components.  In electricity it is much easier to pull current with a ground than to push electricity with a positive.