From NASA, the launch won't happen until later in the week, at least:
Technicians and engineers at NASA’s Kennedy Space Center in Florida are narrowing in on the likely source of what caused heaters on a fuel line for space shuttle Endeavour’s auxiliary power unit-1 (APU-1) to fail on Friday and scrubbing the first launch attempt for the STS-134 mission. But because of work associated with fixing the problem, launch teams will not be able to make a launch attempt tomorrow. Teams will meet Monday and are expected to determine a new “no earlier than” next launch attempt for Endeavour at that time.
Technicians began testing systems associated with the heaters yesterday afternoon and into the overnight hours. Test results indicate the problem is with a power control box, the aft load control assembly-2 (ALCA-2) in Endeavour’s aft compartment. Teams are working on plans to replace the box or any faulty associated hardware. The launch team currently is backing out of launch countdown operations.
There still are numerous factor to be worked out, but just based on the amount of time needed to do the fix, a new launch attempt wouldn’t happen before the end of the week, at the soonest.
Endeavour’s six astronauts are heading back to NASA’s Johnson Space Center in Houston for a few days of additional training before they return for the next launch attempt. The crew’s families also are going to return home today.
NASA Managers will hold a news conference update briefing on NASA TV at 2 p.m. EDT.