1. Consult a wiring diagram: A factory service manual for your specific year and model Chevy truck (Thunder is a trim level, not a model) is the most reliable source. These diagrams show the exact wire colors and their locations. You can often find these online through sites like Helm Inc. (the official GM manuals) or various automotive repair websites.
2. Trace the wires: Carefully follow the wires from the oxygen sensor connector back towards the engine control module (ECM). This will allow you to see the wire colors firsthand, but be cautious not to damage anything. Make a note of which wire goes to which pin on the connector.
3. Use a multimeter: If you're comfortable working with electrical tools, you can use a multimeter to test the voltage at each wire to identify the signal wire (which will have a fluctuating voltage). This requires some electrical knowledge.
In short: Don't rely on generalized color codes found online. Use a wiring diagram or carefully trace the wires yourself for accuracy. This is important for proper sensor installation and functionality.
