* Faulty Horn Relay: This is the most common cause. The relay is a small switch that controls the power to the horn. If it's malfunctioning, it can send power to the horn intermittently or constantly, even when the steering wheel isn't being pressed.
* Short Circuit: A short circuit in the wiring leading to the horn can provide a continuous power supply, causing it to honk. This could be due to damaged insulation, frayed wires, or corrosion.
* Steering Wheel Clock Spring: This spiral-shaped cable in the steering wheel column carries the horn signal. If it's damaged or worn, it can intermittently or continuously ground out the horn circuit, triggering the horn to sound.
* Body Control Module (BCM) Malfunction: In newer Pontiacs, the BCM controls many electrical functions. A faulty BCM can send incorrect signals to the horn circuit, leading to unintended activation.
* Water Damage: Moisture in the electrical system can cause corrosion and short circuits, potentially triggering the horn.
* Faulty Horn Button: While less likely if the horn is honking *without* the button being pressed, a faulty horn button could be intermittently grounding the circuit.
Troubleshooting Steps (Proceed with caution, and if unsure, consult a professional):
1. Check the Horn Relay: Locate the relay (usually in a fuse box under the hood or dashboard). Try swapping it with a relay of the same type (if possible, visually check the relay for signs of damage).
2. Inspect Horn Wiring: Carefully inspect the wiring harness leading to the horn for any visible damage, fraying, or corrosion.
3. Check the Horn Button: See if the horn button itself is faulty.
4. Disconnect the Battery: This is crucial to prevent further damage. Disconnect the negative battery terminal before doing any significant electrical work.
If you're not comfortable working with car electronics, it's best to take your Pontiac to a qualified mechanic. Improperly diagnosing and fixing electrical problems can lead to more serious issues.
