Williams' FW33 car will feature its KERS system for the season opening Australian Grand Prix next weekend.
Rubens Barrichello had admitted last week that the British team was considering not using the system in Melbourne due to not fully understanding recent technical problems.
The latest problem was at the Barcelona test, with technical director Sam Michael admitting to Auto Motor und Sport: "We know what caused the failure, but we don't know why."
Having not used KERS in 2009, Oxfordshire based Williams designed its own battery-based system for this season.
We'll be racing KERS in Melbourne
"Just spoke to Sam," a spokesman said on Williams' official Twitter feed. "(He's) back in factory with designers. Reviewed KERS problem and good news is we'll be racing KERS in Melbourne."
Australian Michael told Auto Motor und Sport that KERS is worth at least four tenths per lap at Barcelona.
And he said the FW33 will make "a big step" forwards in Malaysia early next month when a Red Bull-like exhaust layout is ready.