Do you know exactly what the controller is doing wrong? If not, knowing how it works internally is about useless. The one thing about experience that can't be replaced with book knowledge is the ability to diagnose by understanding whats missing; instead of trying to add up all the parts.

You can verify the function of all the components and never find whats wrong with the system.

The KE controller does two things (ONLY TWO THINGS). It controls the current to the EHA and controls the Idle valve for idle speed control. Which of these two things is it doing wrong? AND of course as it is doing this thing what does the electric siganture look like? If you don't know this EXACTLY then you are on a fishing expedition not a car repair expedition.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician