1994 GMC Jimmy Owner's Manual - Page 264

Brakes Brake Master Cylinder Your brake master cylinder is here. It is filled withDOT-3 brake fluid. There are only two reasons why the brake fluid level in your master cylinder might go down. The first is that the brake fluid goes down to an acceptable level during normal brake lining wear. When new linings are put the in, fluid level goes back up. other reason is that fluid leaking out of the The is brake system.If it is, you should have your brake system fixed, since leak a means that sooner or later your brakes won't work or won't workat well, all. So, it isn't a good idea to "top your brake fluid. Adding brake fluid off' won't correct a leak. you add fluid when your linings are worn, then If you'll have too much fluid when you new brake linings.You should add get (or remove) brake fluid, as necessary, only when work is done on the brake hydraulic system. Refer to the Maintenance Schedule to determine when to check your brake fluid. See "Periodic Maintenance Inspections" in the Index. 6-28 !