Where is the electrical spark control unit or ESC in a 1993 GMC K15 4x4 truck?

You're likely referring to the ignition control module (ICM), not an ESC. The ESC is typically found in electronic stability control systems, not in older vehicles like a 1993 GMC K15.

The ICM, responsible for controlling the spark timing and ignition, is usually located under the hood, near the distributor.

To find it in your specific truck, follow these steps:

1. Open the hood.

2. Locate the distributor. It's usually a round, black cylinder near the center of the engine.

3. The ICM is often mounted on the distributor or very close to it. Look for a small, rectangular box with wires connected to it.

Note:

* There are other components in the ignition system besides the ICM, like the coil and the ignition switch.

* It's always best to consult the owner's manual or a repair manual for specific location information for your vehicle.

If you're unsure about the location or any repairs, it's always best to consult a qualified mechanic.