I replaced the brake light switch late tonight and the error codes are gone and so all is well again.

But there is one thing I wish someone could help ID the K40 relay or module in my 2003 E320. The internet says the engine fuse panel is on the passenger side, but that's not true.
My 2003 E320 has a fuse panel on the drivers side on the engine. Does that make my E320 a late 2002 or an earlier 2004?

Does anyone know for sure?

__________________
1998 Land Rover Range Rover 66K Miles
1988 300SE Totaled in 1998, hit by drunk driver, but we walked away OK
1989 420SEL 140,000, just warming up. Total by 18 wheel gas truck rear ended, but refused to lose another MB. Had it repaired cost $10,000+ Great Car again SOLD it for a 2003 C320 to save on gas
1991 2500 Suburban 454, 130,000, Best truck in the world. SOLD it out right.
1952 8N Tractor 1,000,000-/+