Provided you are NOT using Alternate/Parking Brake, then the tripple indicator will not indicate anything. As a basic, in order to get Normal Braking you must meet the following conditions...Good Green Hydraulic Pressure, At least one channel of the BSCU Operative and the parking brake in the OFF position.
The minute the A-skid/NWS switch is placed in the OFF position, you are in effect switching off the BSCU...hence you are not meeting the requirements for Normal Braking. You are therefore in Alternate Braking and when you brake you will see movement of the Tripple Indicator pressure readings.
From the AMM...
The braking is normal:
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when the Green high pressure is available,
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when the A/SKID & NOSE WHEEL control switch is in the ON position,
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and when the PARK BRK control switch is in the OFF position or the PARK BRK control is in the ON position and the parking brake pressure really applied is less than 35 bar (507 psi).