1. Verify Bulb Installation & Type:
* Correct Bulbs: Double-check you installed the *correct* type of bulbs. A seemingly minor difference can cause failure. Consult your owner's manual or a reputable auto parts store to confirm.
* Securely Installed: Make sure the bulbs are fully seated in their sockets and clicked into place. A loose connection is a common culprit.
* All Bulbs: Check *all* brake lights – the third brake light (high-mounted stop lamp) in addition to the left and right taillights.
2. Wiring and Connections:
* Wiring Harness: Inspect the wiring harness leading to the brake light sockets for any visible damage, breaks, corrosion, or loose connections. Pay close attention to areas where the wires might be pinched or rubbed against metal.
* Sockets: Carefully examine the brake light sockets themselves. Corrosion or damage within the socket can prevent a good connection. Clean them with a wire brush or electrical contact cleaner if needed.
* Ground Connection: Brake lights require a good ground connection to work. Locate the ground wire for the taillights (often a bare metal point on the body of the vehicle) and ensure it's clean and making solid contact. Corrosion here is a frequent problem.
3. Brake Light Switch:
* Location: The brake light switch is usually located near the brake pedal.
* Testing: You might need a multimeter to test the switch. With the ignition on, press the brake pedal. You should have continuity (a closed circuit) between the switch terminals. If not, the switch is likely faulty and needs replacing. (Consult a wiring diagram for your specific Jeep model to find the correct terminals to test).
4. Brake Light Fuse (Again):
* Multiple Fuses: Some vehicles have multiple fuses related to the brake lights, or one fuse might control a circuit that feeds into others. Check your owner's manual for the complete fuse box diagram and double-check *all* possibilities.
* Visually Inspect: Sometimes a fuse can appear intact but still be blown. Carefully inspect each fuse for any signs of internal damage, even if the wire appears fine.
5. BCM (Body Control Module):
* Rare but Possible: In some cases, a faulty Body Control Module (BCM) can prevent the brake lights from working. This is less likely than the other problems, but if everything else checks out, it's something to consider. Diagnosing a BCM issue often requires specialized tools or a professional mechanic.
6. Wiring Diagram:
* Essential: Obtain a wiring diagram specific to your 2002 Jeep Liberty. This will show you the exact path of the brake light circuit, allowing you to pinpoint the problem more accurately. You can usually find these diagrams online (through repair manuals or forums) or at an auto parts store.
Safety Note: If you're not comfortable working with car electrical systems, it's best to take your Jeep to a qualified mechanic. Improper wiring can be dangerous.
