If you see the alternator gauge dropping, chances are the alternator is the problem. Do me a favor. I want you to check the alternator output. It is very easy to do. All you need is a volt meter or a multi meter. Here is a link that explains how it is done:
I don't know if you need it, but here is a link you may find helpful:
If you find the alternator isn't producing and needs replaced, here is a link that shows in general how it is done:
Here are the directions specific to your vehicle for replacement. The attached pics correlate with the directions.
2002 Chevy Truck K 1500 Truck 4WD V8-5.3L VIN T
Vehicle Starting and Charging Charging System Alternator Service and Repair Procedures Generator Replacement
CAUTION: Refer to Battery Disconnect Caution in Service Precautions.
1. Disconnect the negative battery cable.
2. Remove the accessory drive belt.
3. If necessary, remove the engine sight shield.
4. Disconnect the generator electrical connector (3).
5. Remove the generator cable from the generator, perform the following:
5.1.Slide the boot down revealing the terminal stud.
5.2.Remove the generator cable nut from the terminal stud.
5.3.Remove the generator cable.
6. Remove the generator bolts.
7. Remove the generator.
1. Install the generator.
NOTE: Refer to Fastener Notice in Service Precautions.
2. Install the generator bolts.
Tighten the generator bolts to 50 N.m (37 lb ft).
3. Install the generator cable to the generator, perform the following:
3.1.Install the generator cable.
3.2.Install the generator cable nut to the terminal stud.
Tighten the generator cable nut to 9 N.m (80 lb in).
3.3.Slide the boot over the terminal stud.
4. Connect the generator electrical connector (3).
5. If necessary, install the engine sight shield.
6. Install the accessory drive belt.
7. Connect the negative battery cable.
Let me know the results you get when checking the alternator. Also, if you have other questions, let me know.
Images (Click to enlarge)
Thursday, September 3rd, 2020 AT 6:25 PM