For the 2002 - 2006 Nissan Altima, the ECM and TCM are both located under the dashboard, behind the glove box. You must remove the glovebox to access these modules. Remember that any yellow wires or connectors are for the air bags. You should probably refer to a service manual before accessing anything electrical/electronic.
Behind glove box compartment
righthand side firewall behaind the strut bar.....
It is under the passenger seat
The ECU on a 2007 Nissan Maxima is located on the dash of the vehicle. This is used to reset various lights and other functions on the vehicle.
The ECU is located underneath the wooden panel/ underneath the carpet on the passenger side, below the glovebox
The ECU is located to the right of the gas pedal. If you look to the right of the gas pedal you should see two pieces of detachable plastic, a small piece connected to a larger piece. simply pop off the smaller piece (closest to firewall) by removing the grommet (black with a Phillips head) and unlatching it from its hinges. The ECU is located behind this piece in a slanted position. The ECU is a finished silver box with a white decal. If your trying to remove it you need to remove the glove box, center console box, and center console along with part of the dash. i just removed mine and replaced my ECU in my 96 Nissan altima GXE 2.4L this gives enough room to get your hand behind and remove the twe screws holding it in.
The ECU/BCM on the 2002 Buick Rendezvous CX is located underneath the Driverside seat.
underneath passenger side seat
The ECU is located underneath the wooden panel/ underneath the carpet on the passenger side, below the glovebox
The ECU is located underneath the wooden panel/ underneath the carpet on the passenger side, below the glovebox
Behind the blower motor
under the dash