The starting sequence involves several components and their related circuits, including:
* Ignition Switch: This is the primary initiator.
* Neutral Safety Switch: Prevents starting unless the transmission is in Park or Neutral.
* PCM (Powertrain Control Module): The PCM plays a crucial role in monitoring various inputs (like the neutral safety switch) and authorizing the starter circuit.
* Starter Solenoid: This is the electromechanical switch that engages the starter motor. It's often mounted directly on the starter itself.
* Various Fuses and Relays: Several relays and fuses within the underhood fuse box and interior fuse panel protect and control aspects of the starting circuit. These aren't specifically labeled "starter enable" but are involved in the process.
To diagnose a starting problem, you'll need to use a wiring diagram specific to your 1991 Cadillac Sedan DeVille and systematically check:
1. Fuses: Check all fuses related to the ignition system and starter.
2. Neutral Safety Switch: Ensure it's functioning correctly.
3. Ignition Switch: Verify it's providing power to the correct circuits.
4. Starter Solenoid: Check for proper operation. A clicking sound might indicate a faulty solenoid.
5. PCM: A faulty PCM can prevent the starter from engaging. This is the most difficult component to test without specialized tools.
6. Battery and Connections: Make sure the battery is charged and the connections are clean and tight.
In short, there's no single "starter enable relay" to find. A proper diagnosis requires using a wiring diagram and testing various components within the starting circuit. A repair manual for your specific year and model will be invaluable.
