Where is the VCM on a 2003 Chevy pickup?

The Variable Cam Timing (VCT) system on a 2003 Chevy pickup (assuming you mean the 4.3L or 5.3L engine, as the 6.0L used a different system) doesn't have a single, easily identifiable "VCM" component like a separate box or module. The VCT functionality is integrated into the engine itself. Specifically:

* It's within the cylinder heads: The VCT solenoids and associated mechanisms are located inside the cylinder heads, controlling the camshaft timing. You won't see a separate "VCM" unit.

To access anything related to the VCT system, you'd need to delve into the valve train area of the engine, which requires significant mechanical knowledge and tools. This is not a DIY task for someone lacking engine repair experience. If you're troubleshooting a problem with VCT, diagnosing it yourself is difficult. It's usually best handled by a qualified mechanic.