Why would the brake lights work in your 1999 Lincoln town car but not rear lights?

If the brake lights work but the regular tail lights don't on your 1999 Lincoln Town Car, the problem likely lies in the tail light circuit itself, not the brake light circuit. They are separate circuits, even though they share the same bulbs. Here's a breakdown of possible causes:

* Burnt-out tail light bulbs: This is the simplest and most common cause. Check both bulbs thoroughly. Sometimes a filament can break but still allow the brighter brake light filament to work.

* Blown fuse: The tail lights and brake lights often have separate fuses. Check your owner's manual for the fuse box location and diagram. Look for fuses specifically labeled for the tail lights (or park lights/running lights).

* Faulty tail light switch: While less likely given the brake lights work, a failing switch could be selectively affecting the tail light circuit.

* Wiring issues: A break or short in the wiring dedicated to the tail lights is a possibility. This could be anywhere from the switch to the light sockets themselves. Check for corrosion, broken wires, or loose connections at the connectors near the lights and possibly near the fuse box.

* Faulty ground: A poor ground connection can prevent the tail lights from working. Ensure the ground wires connected to the rear lights are clean and properly connected to the car's chassis.

* Multi-function switch (turn signal/wiper switch): In some rare cases, a failing multi-function switch can impact tail light function but leave brake lights operational.

Troubleshooting Steps:

1. Check the bulbs: This is the first and easiest thing to do.

2. Check the fuses: This is the next easiest step and often solves the problem.

3. Visually inspect the wiring: Look for any obvious damage to the wiring harness running to the rear lights.

4. Check the ground connections: Clean and tighten the ground connections at the rear lights.

5. Use a multimeter: If you're comfortable with basic electrical testing, a multimeter can help pinpoint the problem in the wiring or the switch. Test for voltage at the light sockets with the lights turned on. You should have voltage if the wiring and switch are functioning properly.

If you're not comfortable working with car electrics, it's best to take your Town Car to a qualified mechanic for diagnosis and repair. The problem could be more complex than a simple bulb or fuse.