* Cooling Fan Relay: This is a very common cause. The relay controls the cooling fan, which often runs for a short time after the engine is shut off to cool things down. The clicking you hear is the relay's internal contacts engaging and disengaging. If the relay is failing, it might make a clicking noise intermittently or for longer than usual.
* HVAC Blower Motor Resistor: This resistor controls the fan speed for your heater/AC. A failing resistor can create clicking sounds, especially when the system is turning on or off. The two-minute duration might be the time it takes the system to fully cycle through its post-shutdown functions.
* Other Relays: While less likely, a failing relay for other electrical components could also produce a clicking noise. This could be related to anything from power windows to the fuel pump. However, the two-minute timing points more strongly to cooling system-related components.
* Electrical Connection Issues: Loose or corroded connections under the dash can also cause clicking sounds as components try to draw power. This is more likely to be a consistent problem, not just limited to the start/stop sequence.
Troubleshooting Steps:
1. Listen Carefully: Try to pinpoint the exact location of the click. Is it coming from the HVAC system area, or somewhere else under the dash? This will help narrow down the possibilities.
2. Check the Cooling Fans: After shutting off the engine, observe whether the cooling fans run for the usual short period. If they're not running or running for an unusually long time, suspect the cooling fan relay.
3. Inspect Relays: If you're comfortable working on cars, locate the relays under the hood (often in a fuse box) and visually inspect them for any signs of damage, such as corrosion or burning. You could even try swapping the cooling fan relay with a known good relay (if you have one of the same amperage) to see if the clicking stops. Use caution when working with car electrical systems.
4. Check Fuses: While less likely to *click*, blown fuses can cause related problems and should be checked.
5. Professional Help: If you're not comfortable working with car electrical systems, it's best to take your Silverado to a mechanic. They can diagnose the problem accurately and safely repair it.
The two-minute timeframe strongly suggests a timed function, making the cooling fan relay the most probable suspect. However, a thorough inspection by a professional or careful DIY diagnostics will provide a definitive answer.
