Does this "wire" run the length of the cap and sit in small detents in the top of the cap, and does the cap cover both primary and secondary reservoirs? If so, it just snaps to the side and pivots down to the side of the master cylinder. The cap then lifts off. remember to wipe off the cap and master cylinder before you take the cap off, and don't leave the master cylinder open to the atmosphere too long. Brake fluid loves to absorb moisture from the air.
If the brake light on the dash is coming on intermittently, the fluid in one of the reservoirs is low, typically the main, and may indicate that it's time to replace the pads up front. Possibly even change the rotor if its near its minimum thickness.
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