Where is the fuse located that supplies energy to the liscence plate light of a 99 blazer

Look at factory wiring diagrams an test electrical circuit.

Factory Service Manuals - NICOclub

System Description EKS008NW Control of the parking, license plate, and tail lamp operation is dependent upon the position of the lighting switch (combination switch). When the lighting switch is placed in the 1ST position, the BCM (body control module) receives input signal requesting the parking, license plate, and tail lamps to illuminate. This input signal is communicated to the IPDM E/R (intelligent power distribution module engine room) across the CAN communication lines. The CPU (central processing unit) of the IPDM E/R controls the tail lamp relay coil. When energized, this relay directs power to the parking, license plate, and tail lamps, which then illuminate. Power is supplied at all times ? through 10A fuse (No. 41, located in the IPDM E/R) ? to tail lamp relay, located in the IPDM E/R, and ? through 50A fusible link (letter f , located in the fuse and fusible link box) ? to BCM terminal 70. With the ignition switch in the ON or START position, power is supplied ? through 10A fuse [No. 1, located in the fuse block (J/B)] ? to BCM terminal 38. With the ignition switch in the ACC or ON position, power is supplied ? through 10A fuse [No. 6, located in the fuse block (J/B)] ? to BCM terminal 11. Ground is supplied ? to BCM terminal 67 ? through grounds F14, M57 and M61.

Number plate lights aren't usually fused separately but as they are mostly supplied by the sidelight/parking light circuits, the fuses of those circuits also protect the number plate lamp(s). These days there are usually two fuses - one each for the left and right. One side usually also supplies the instrument lights and the other side the number plate lamp(s), though where there are two number plate lamps it isn't unknown for each to be supplied separately from each lighting circuit.

It is a real pain to replace this light.



License plate lights

There isn't one. It is tied into the parking lights. Bad bulb, socket, or wires.

I dont think the fuse would blow, I would change the bulbs

Remove the inner door panel, and you will
most likely find that the window regulator broke

Not the fuse,you said you put window down

Order an owners manual----Helm.Com

check the fuses first then the bulbs

There are a couple of fuses you will want to check. They are located in the under hood fuse box. The TBC ( truck body controller) and ATC (automatic transfer case) fuses.
If both are good, take the truck to your local Auto Zone and ask them to scan the vehicle for "trouble codes". Write the codes down and respond back.
Below is a diagram of the under hood fuse box and the fuse locations.

Does the fuse have power in and out when a test light is used? This test would be run with the light switch on.