I am trying to replace the ECM of my 1989 Chevrolet Astro van but do not know how to locate the ECM. According to the diagram on its service manual, it's a series "M" van and the ECM is located close to the firewall of the passenger side compartment, on the "right hand side plenum panel" with four mounting screws. I looked at the passenger side but had no clue where it could be. Should I remove the entire plastic vent housing facing the passenger seat first in order to find the ECM?
Any help is appreciated.
Tom