DIY, change the ignition coils on your GMC Sierra, the model made in 2002, with the Vortec V8 engine. The replacement is the same for most of the models equipped with the 4.8, 5.3 and 6.0L Vortecs. The only tool you’ll need is a 7 mm socket wrench, with a ratchet and extension. The repair is quite simple and it will take you about 10 minutes for each coil.
You can start the repair by opening the hood of the car. There should be eight coils on your car, looking like the two in the image below.
You should work to remove the coils one at the time and in order to do that, first you will need to unplug the electrical connector on the upper side and then the spark plug wire below (see picture below).
At this point, you will have to remove the two 7 mm bolts that secure the coil, seen in the next image. They can be removed easily, with an appropriate socket.
After you get rid of all the retainers, you will be able to remove and replace the old coil with a new one. The new part should bolt in just like the original. Reconnect the plug wire and the electrical harness and that should be it. This is all you have to do, if you plan to remove and replace the ignition coils on your GMC Sierra made in the year 2002, equipped with the V8, Vortec engine.