Is my alternator going out?

[slow_c1500]

Would i check the ignition switch by checking fuse #20 in the dash fuse block? And if so, would I just probe it with a multimeter, and what voltage should I expect?

 

[Schurkey]

I'd be checking the various outputs of the ignition switch--dash light power, ignition power, and so forth.

 

[1998_K1500_Sub]

Would i check the ignition switch by checking fuse #20 in the dash fuse block? And if so, would I just probe it with a multimeter, and what voltage should I expect?

Before you check the IGN switch, check the battery connections as those seem to be a likely source of your symptoms.

If problems remain, THEN start looking at the IGN switch.

I'd be checking the various outputs of the ignition switch--dash light power, ignition power, and so forth.

^^^ this

With engine off:

Put a DVM on each switch output and repeatedly wiggle the switch around, move it through it's various positions, while watching for:

- instantaneous / momentary loss of voltage (indicative of a momentary open circuit within the switch when one should not exist) or

- variations in voltage readings, e.g., the measured voltage changes from 12.1V to 10.9V (indicative of poor contacts / contact resistance within the switch)

You may want to repeat these tests while presenting different electrical loads (light, heavy) to the switch, to the extent possible. See the attached .pdf which shows the circuits downstream of the IGN switch for 1998 GMT400s.

Others may suggest addn'l tests, these just come to mind.

Also not sure if this is related but a few days before those events, there was an instance where it would only start when i gave it throttle, and it would die when i put it into gear.

^^^ Let's hold on this until you've got the other issues ironed-out.