It is crucial that your IC pump work in order to prevent detonation and optimize your truck’s performance.
There are several steps and methods to test the pump.

Simple, stock setup test.

Under the dash there is an “ALDL” (Assembly Line Diagnostic Link) connector. This is a diagnostic port you can use to help with several things on your truck.
To test the pump, you need to put the computer into diagnostic mode. In this mode, you can check engine codes, and verify if the tps and ic pump are working.

Take a paper clip and bend it into a U shape. Your aim is to connect two adjacent ports on the ALDL. The two ports horizontally next to each other on the top, right corner of the ALDL need to be connected.
One is a ground, the other is the diagnostic port. When you connect the two, you will notice the check engine light flashing.
Make sure the paper clip stays engaged, and walk around the front of the truck. You’ll hear the idle air control motor chattering in the throttle body.
Listen lower to the pump under the front bumper to see if you can hear it running. If not, remove the upper IC cap and see if you can spot motion in the water.

If neither offer any sign of the pump working, remove the paper clip, and check the IC pump fuse. It is located behind the alternator in a black fuse holder.
If this appears normal, You need to verify the pump is getting power.

Get under the front bumper and disconnect the IC pump wire(its located behind the intercooler radiator, either hanging visibly, or up around the sway bar). Re insert the aldl paperclip and check the connector for power . If you are getting power here, the pump is dead. If not, then the relay may be bad.

Remove the IC relay (described in how to hot wire the IC pump).

Using a multi meter, verify that there is power making its way to the relay.

If there is, replace the relay, if there isn’t, then the problem lies in the power wire to the relay.