If it is only on the outside of the backing plate, it will be the brake line. If it is on the insede it will be the wheel cylinder needing replaced.
where is it leaking from?
A 2002 Chevy Tahoe uses the standard brake fluid in passenger vehicles with power brakes. It is known as DOT3 brake fluid.
DOT-3
The brake booster is leaking vacuum pressure. If you look under the hood its black and round and located behind the brake fluid reservoir
Factory says to use DOT 3 only.
Axel seals leaking grease on the brake shoes. Wheel cylinders leaking brake fluid. To much brake dust in the drums.
Sounds like the clutch master or brake master is leaking hydraulic fluid.
It all depends on what part is leaking what fluid. Brake cylinder would leak brake fluid. Axle seal would leak gear oil.
How many quarts of transmission fluid does a 2004 Chevy tahoe take
brake fluid leaking from a brake drum indicates the brake slave cylander on that wheel is leaking and needs to be replaced you will not see the actual leak with out removing the brake drum
Check the brake fluid reservoir and be certain that it is full. If it's just a matter of the disk brake pads wearing, you might just need to add a little fluid, but if it's leaking fluid you need to get it repaired.
transmission fluid