05 Altima 3.5 wiring harness swap. Please advise
 

Hello, I have a short somewhere that began with the ground wire from the neg battery terminal that broke where it connects to the tranny. That issue fried the ECU and the "eng ign / ECCS fuse blows every time the car cranks. Car also threw a cam sensor code. Replaced both cam and crank sensors, bank 1 o2 sensors, all coil packs.


Took it to the dealership knowing that the ECU was fried along with a new ECU I brought. After they attempted to reflash the new ECU they said theres now a short somewhere in the wiring harness that fried the new $1000 ECU. They recommend a total wiring harness replacement after charging me $380 to "diagnose" the fact there is a short somewhere.


My thought is to change the entire wiring harness my self rather than take it to another mechanic who can track down the short.


The question is how many major components will need to be taken out to do the whole engine harness swap and if it's not too difficult of a job? Any other thoughts on a better solution would be appreciated. Thanks in advance