My 2003 Cadillac CTS has 4 vacuum hoses at the rear of a plastic cover on top of the intake manifold. You can see them near the beginning of this video The mechanic leaves the cover dangling from the tubes I'm asking about.

I'd like to know where they go and what they do. I've looked online for a diagram or other explanation, but apparently I don't know enough to formulate a good Google query.

1 Answer 1


Here's a diagram from the service manual. Searching, "2003 Cadillac CTS Vacuum Diagram" provides similar results.

enter image description here

  • If I'm reading that right, That's 14 - 13 - 12 - 14,(EVAP and Crankcase.)
    – TecBrat
    Commented Oct 7, 2017 at 22:38
  • @TecBrat Correct
    – Ben
    Commented Oct 7, 2017 at 22:39
  • As to the "provides similar results", The diagram is somewhat abstract compared to the real life setup and I couldn't recognize it for what it was. Thanks for bridging that gap for me.
    – TecBrat
    Commented Oct 10, 2017 at 13:56

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