OK ...I think I am wrong on the yellow as a turbo protection relay. Based on the shop write up it cuts the fuel pumps and then cuts the CDI box.... as it says for an orderly reduction in combustion... I guess this is part of a shut down procedure to clear the cylinders of gas due to the continuous fuel delivery process...The over boost relay is the round relay- red/blk and that cuts the power to the fuel pumps when the over-boost sensor causes the relay to trip....
John Walker if you are out there ....please help us clarify..
1987 930 -Guards Red
2001 740I sport Blk
2011 F-150 supercrew Blk
2014 X3 2.8 white
"What goes around comes around..."