Will a 2003 ecm for a 2004 Cadillac cts 3.6v?

SOURCE: Left Front Blinker Replacement on 2004 CTS

changing the blinker on a CTS

SOURCE: Need repair manuel for 2004 Cadillac CTS

Similar to obtaining an owner's manual, you can obtain a repair manual from the same sources identified in this handy, diagnostic article:
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Owners_Manual.htm
This should defintely help
Brad

SOURCE: cadillac cts cranks but won't start

My 2003 CTS would not start on the first, second or third try after filling the gas tank. Finally after several months of this occuring every two weeks a check engine light came on. It was the evac purge valve. Tom

SOURCE: how do you loosen the tensioner pulley on a cadillac cts 2003

You forgot to rate other requst.

Testimonial: "thanks for all of your help"

SOURCE: vapor canister 2003 cadillac cts

it will look something like this:
and is usually located on the fender well on the engine side toward the front corner of the car (it may be inside the fender itself)
there would be 2-3 large vacuum hoses going to it which will help in finding it.