Jul.6 (GMM/Inautonews.com) Renault has reverted to an older specification of its alternator for the use of customers Red Bull, Lotus, Williams and Caterham this weekend at Silverstone.

The decision follows the French supplier’s struggles to get to the bottom of the problems that caused Sebastian Vettel and Romain Grosjean to retire last time out at Valencia.

A similar issue was also reportedly linked to a problem suffered by Vitaly Petrov at Monaco.

“This (problem) is a great puzzle,” Germany’s Auto Motor und Sport reports. “Not even Renault knows exactly what went wrong.”

Remi Taffin, Renault’s track boss, confirmed that factory tests after Valencia showed “signs” of the problem recurring, but no definitive “conclusions”.

He confirmed that 2011-specification alternators have therefore been supplied to Renault’s customers for the British grand prix.

“We are confident that it will not happen again, even though at the moment we cannot identify the causes of the problems 100 per cent.”

Taffin added that Renault has also made tweaks to the engine maps.

“In our opinion, the countermeasures are sufficient,” he said.