1. Verify the Brake Light Switch Replacement:
* Correct Switch: Double-check that you installed the *correct* replacement brake light switch. A wrong part will cause issues.
* Proper Installation: Ensure the switch is properly seated and adjusted. Sometimes, a slight misalignment can prevent it from working correctly. Consult a repair manual for the correct installation procedure.
* Switch Testing (if possible): If you have a multimeter, test the switch's continuity (closed circuit) when the brake pedal is depressed and open circuit when released. This confirms the switch itself is functioning correctly.
2. Wiring Inspection:
* Brake Light Switch Wiring: Carefully examine the wiring harness connected to the brake light switch. Look for:
* Broken wires: Look for any breaks, chafing, or fraying in the wires.
* Corrosion: Check for corrosion on the terminals or connectors. Clean them with a wire brush and electrical contact cleaner.
* Loose Connections: Make sure the wires are securely connected to both the switch and the harness.
* Wiring Harness to Rear Lights: Trace the wiring harness from the brake light switch to the rear lights themselves. Look for damage along the entire length. This harness often runs under the car and can be prone to wear and tear.
* Ground Connections: Poor ground connections can cause all sorts of electrical gremlins. Check the ground connections for the brake light circuit. These are typically found on the chassis near the rear of the car. Clean any corrosion from these points.
3. Multi-Meter Testing:
* Power at the Switch: With the ignition on, use a multimeter to check for power at the wires going to the brake light switch. You should have power on one wire (with the engine running).
* Power at the Brake Lights: With the ignition on and brake pedal not pressed, check for power at the wires going to the rear brake lights. There should be *no* power. If there is, this points to a short or a problem in the wiring harness.
* Continuity Test: With the ignition off, test continuity (connection) between the brake light switch connector and the tail light socket to rule out a break in the wire.
4. Consider the Stop Lamp Fuse (again):
While you mentioned checking fuses, some vehicles have multiple fuses related to the brake lights. Consult your owner's manual to ensure you've checked *all* the relevant fuses. A blown fuse can sometimes blow again quickly if there's a short circuit.
5. Other Potential Culprits:
* Brake Light Control Module (if applicable): Some vehicles have a brake light control module. This is less likely on a 1996 Cadillac but is worth investigating if the above steps don't solve the problem.
* Central Body Control Module (BCM): A faulty BCM can cause unusual electrical issues. However, this is usually diagnosed by a professional mechanic due to the complexity of the system.
6. Professional Help:
If you're not comfortable with electrical diagnostics or the problem persists, it's best to take your Cadillac to a qualified mechanic or auto electrician. They have the tools and experience to diagnose and fix the issue more effectively. Trying to troubleshoot complex electrical systems without the proper knowledge can lead to further damage.
