I think the SIBs are reproduced in the Bentley service manual. The heated steering wheel issue described in this thread is listed as a known issue with an explanation of "At the time of this printing, no repairs were required for this condition."
The cause, it says, is "For the first few seconds after start-up, voltage levels may dip momentarily when electrical consumers are switched on. If the supply voltage dips below the threshold for the heated steering wheel, it will be switched off."
