Where is the vacuum diagram or system in a 1977 Cadillac Coupe deVille?

There isn't a single, readily accessible "vacuum diagram" in the way you might find in a modern car's owner's manual or under the hood. 1977 Cadillacs, like many cars of that era, relied heavily on vacuum for various systems (power brakes, HVAC, transmission, etc.), but the routing was often implied through the physical placement of components and hoses.

To find the equivalent of a vacuum diagram for your 1977 Cadillac Coupe deVille, you'll need to consult a few resources:

* Factory Service Manual: This is the best option. A factory service manual will have detailed diagrams showing the vacuum lines and their connections to various components. You can often find these online through reproduction companies or used parts sellers.

* Chilton's or Haynes Repair Manual: These are less detailed than factory manuals but may still provide some visual aids or descriptions of the vacuum system.

* Under the Hood: Carefully examine the engine compartment. Trace the vacuum lines from the intake manifold (a major source of vacuum) to see where they go. Many lines are color-coded, and you may find vacuum-operated components labeled. However, without a diagram, this method is prone to errors.

* Online Forums: Cadillac enthusiast forums (like those dedicated to classic Cadillacs) could be a great place to ask for help. Someone may have a diagram or be able to guide you based on their experience.

Important Note: Working with the vacuum system requires care. Incorrectly routing vacuum lines can lead to malfunctioning components or even engine damage. If you're unsure, it's best to consult a mechanic specializing in classic cars.