* Burnt-out bulb: This is the simplest and cheapest fix. Check the left front turn signal bulb (the one in the headlight assembly) and replace it if it's blown. A burnt-out bulb can cause the system to default to a constant on state.
* Bad flasher relay: The flasher relay is a small electrical component that controls the blinking rate of your turn signals. A faulty relay can cause the lights to stay on constantly or not blink at all. This is a common cause of this problem. You'll likely find this under the dash or in a fuse box. It's usually a small, square or rectangular unit.
* Wiring issue: A short circuit, broken wire, or corroded connection in the wiring harness for the left turn signal can prevent the signal from blinking correctly. This is the most difficult issue to diagnose and requires tracing the wires.
* Turn signal switch: While less likely, a faulty turn signal switch on the steering column could be the problem. This is more involved to replace.
* Multi-function switch (or turn signal stalk): The part that actually contains the turn signal switch mechanism. This is often the problem when the turn signal itself acts erratically in various positions.
How to troubleshoot and repair:
1. Check the bulb: This is the first and easiest step. Replace the left front turn signal bulb if it's burnt out. Test the turn signal again after replacement.
2. Check the flasher relay: Locate your flasher relay (consult your owner's manual or an online repair guide for your specific model). Try swapping it with another relay (like the hazard light relay – if they're the same type) to see if the problem follows the relay. If the problem is with the relay, replace it with a new one from an auto parts store.
3. Inspect the wiring: This is the most challenging step. You'll need to visually inspect the wiring harness leading to the left front turn signal for any damage, corrosion, or loose connections. This may require removing some trim panels. Use a multimeter to check for continuity in the circuit if you're comfortable with electrical testing.
4. Test the turn signal switch (least likely, most difficult): If none of the above solves the problem, the turn signal switch itself may be faulty. Replacing this usually involves accessing it from behind the steering wheel and might require some mechanical skills.
Important Notes:
* Safety First: Disconnect the negative battery terminal before working on any electrical components in your vehicle.
* Owner's Manual: Consult your owner's manual for diagrams and specific locations of components like the flasher relay and fuse boxes.
* Online Resources: Numerous online forums and repair guides offer detailed instructions and troubleshooting tips for 1996 Buick LeSabres. Search for "1996 Buick LeSabre turn signal repair" for more information.
* Professional Help: If you're not comfortable working on your car's electrical system, it's best to take it to a qualified mechanic.
Start with the simplest solution (the bulb) and work your way through the more complex possibilities. Good luck!
