* Faulty Tail Light Switch: This switch is usually located on the steering column and controls the tail lights. If it's malfunctioning, it might not fully disengage, keeping the lights on even when the car is off.
* Short Circuit in the Wiring: A short circuit in the wiring harness leading to the tail lights is a possibility. This could be caused by damaged insulation, frayed wires, or corrosion in connectors. This is especially likely if the problem is intermittent.
* Bad Ground Connection: A poor ground connection can cause all sorts of electrical gremlins, including lights staying on. The ground wire for the taillights might be corroded or loose.
* Faulty Taillight Relay (if equipped): Some vehicles use relays to control the tail lights. A malfunctioning relay could keep the power flowing even when it shouldn't.
* Issues with the Body Control Module (BCM): In some vehicles, the BCM manages various electrical functions. A problem within the BCM could cause the tail lights to malfunction. This is less likely but possible.
* Aftermarket Additions: Any aftermarket additions to the lighting system (e.g., trailer hitch wiring) could have faulty wiring that's causing this issue.
Troubleshooting Steps (in order of ease):
1. Check the Tail Light Switch: Try wiggling the turn signal stalk (if it's integrated with the switch) to see if you can influence the tail light behavior. If there's play and the issue changes, the switch is a strong suspect.
2. Visual Inspection of Wiring: Carefully inspect the wiring harness leading to the tail lights, looking for any obvious damage (broken insulation, corrosion). Pay special attention to connectors.
3. Check the Ground Connection(s): Locate the ground points for the taillights (usually a bolt or screw to the car body). Clean the connection and ensure it's making good contact.
4. Test the Bulbs: Although less likely to be the *cause* of the problem, if a bulb is shorted internally, it *could* be drawing power and staying on. Try swapping the bulbs.
5. Relay Check (if applicable): If your car uses a relay for the taillights, locate it (usually in a fuse box or under the dash) and test it with a multimeter to ensure it's switching correctly.
6. Fuse Check: Check the fuses related to the tail lights. A blown fuse would prevent the lights from working, but a partially blown fuse or a short before the fuse could still cause the problem.
If you're not comfortable performing electrical checks, it's best to take your Toronado to a qualified mechanic. Ignoring this problem could drain your battery and lead to further issues. The intermittent nature makes it harder to diagnose without some testing.
