NASA to Remove and Replace Faulty Switchbox, SpaceRef
"NASA managers have narrowed down the problem to the Aft Load Control Assembly #2 (LCA 2) and in particular they believe the problem is with failed Hybrid Load Drivers within the LCA. The LCA is located in Endeavour's aft avionics bay 5. They will pull out the LCA tomorrow and install a spare on Tuesday. It will take 2 days of testing before they can consider proceeding with a new countdown for a no earlier launch day of Sunday, May 8th, Mother's Day."