Note on Intermittents
WARNING: This page is about a different car, the 1990 Cadillac Fleetwood and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Start engine to charge vacuum reservoir. With engine OFF, select ECM override E.5.7, depress warmer button and fully apply servo. Manipulate wiring and connectors and observe servo. If servo does not remain applied, there is an intermittent open in circuit.