I have a 2001 Maxima GXL with 135K (A/T, no T/C) and the P0505 code. I understand the IACV and potential Engine Mount issues. I've pulled the ECM, and the STA509 chip and the motor mount chip (I think--1st NEC chip to far left when harness is facing you, slightly offset from other 2 NEC chips) are both toasted.
I am going to unplug the engine mount harnesses when I get home, and a new Hitachi IACV and TPS are on order.
I'm concerned about the just having the ECM repaired, though, due to some corrosion I saw on some surface mount resistors. I'd like to order a used/refurb one and have it reprogrammed at the dealer, but I can't find any with the same part numbers.
SO--my big question is this: Is it ok to get one with the same "Big Letters" (3T, in my case) even if the small letters don't match (A56-R63 ZE7)? I read somewhere (here or on maxima.org) that the small letters are just a firmware version, so they change every time the firmware was revised at the factory. Is this true? I plan to have the ECM reprogrammed at the dealer anyway--update and key coding--so would any 3T ECM work once reprogrammed? This is the $300+ dollar question...
TL;DR--Can I use any ECM with the same big letters in my car as long as I get it reprogrammed at a dealer, or do the small dot-matrix letters on the ECM really make a big difference?