i am working on a 2000 3500 with 5.9. got a code that said the shift solenoid has gone up.solenoids tested good, which tells me the ecm has failed. does anyone know where this item is?

 

Under the hood, litterally. Look for the big silver box about the center of the firewall above the engine.

Personally I would check the wiring from the solenoid to the PCM before ruling that the PCM is bad.

And were there any other codes as well?

 

Oh? Did you also test the wiring between the tranny and ECM?

 

there was only one code that said shift solenoid. i don't mess with auto trans. the dealer tested the solenoids and checked the entire tranny and told us the ecm was at fault

 

The dealer? In your initial post it was I and Me, now it's the dealer? Well if the dealer already diagnosed and tested it and you believe them, then why are you wasting our time asking these questions and pretending that you're trying to solve a problem that you already have the answer to?