Windshield Wiper Reservoir Issue
 

My '88 GXL FC is kicking on the Low Wiper Fluid Light and I would like to resolve this issue.

I have a wild assumption that maybe something is missing in the reservoir as any fluid poured into the reservoir does not stay in there as if there is a hole or something.

I guess the first part of my question is, where is this reservoir located and how do I get to it?

It is usually located at the front corner inside the engine bay behind the light assembly.You will see a big circular plastic cap.The neck is held by one 10 mm bolt but it goes to the tank which is well hidden.
Mine was on the driver's side(CDN model) But I do believe they may have had another version where it is on the passenger.
The sensor is IN the tank and the connector is a 4 wire affair that runs the pump and sensor.
If you need to drop that tank it is not easy as you have to take off the brake duct and part of the plastic wheel well shroud(front portion) to get at the mounting bolts.
These bolts (10 mm) usually snap when you take it off)

Your sensor could be at fault. When the sensor believes there is low fluid it sends a ground signal to the idiot lights and it causes the light to turn on. The wire that runs from the tank to the idiot box could also be grounding out accidentally which would also cause the warning light to turn on. If the tank was empty and was left in such a condition for a lengthly period of time then the sensor could be stuck in the low position regardless of the actual fluid level.