Pirelli's Formula 1 tyre test running at Barcelona was cut short today after the 2010 Renault's engine suffered an alternator failure.
The Renault R30 was running with a 2010-specification alternator, which the engine manufacturer described as "similar" to the one used in the first part of this season.
A spokesperson told AUTOSPORT: "Earlier today, an R30 from 2010 being used for Pirelli tyre testing at Barcelona experienced an alternator failure similar to the occurrence in Valencia earlier this season.
"The engine was a 2010 version fitted with a 2010 specification alternator similar to the specification used in the first part of the 2012 season."
Renault made changes to its alternator specification following an investigation after Valencia, when Sebastian Vettel and Romain Grosjean both retired.
But it suffered from further alternator failures at Monza last weekend, including one that put Vettel out of the race, despite modifications being made to the component.
Renault remains confident that it will be able to solve the problems and AUTOSPORT understands that investigations at its Viry base have made significant progress in isolating and resolving the problem.
The firm is confident that measures it will introduce for next weekend's Singapore Grand Prix will solve the reliability problem.
The version of the alternator running on the Pirelli test hack was not a development part, for this is prohibited by the agreement covering tyre testing.
"As per the terms of the tyre testing agreement, we would not use any of the Pirelli tests to test new or development parts," said Renault's statement.