As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOI FLIGHT NR 2303: AFTER START, NR 3 HYD PUMP CAUTION LIGHT REMAINED ILLUMINATED. WHEN NR 3 ISO VALVE SWITCH 'OPEN' HYD NR 3 PRESS REMAINED 0. SWITCH LIGHT INDICATES OPEN. AIRCRAFT RETURNED TO GATE. MAINTENANCE REPLACED NR 3 HYD ACCUM ISO VALVE IAW AMM TASK 29-12-21-000-801 AND 29-12-21-400-801. OPS CHECK AND LEAK CHECK NORMAL. ALSO, REPLACED NR 3 HYD PRESS SWITCH AND RL4 RELAY (PN M6106/19-022). AIRCRAFT RETURNED TO SERVICE.