Hey there
I just wanted to post some results from my E38 cruise control
I took me some time to set up the wiring with the clutch switch 12 volts unless depressed, brake 12 volts when depressed for the TAC and 12 volts disappearing when pressed for TCC.
On the ECM, Brake 12volts when peddle is pressed and ground when not depressed.
But I was still struggling to make the cruise control reliable.
It turns out that you must have all the DTC's cleared Even if they are not illuminating the MIL light.
Dave