Abstract: A system for controlling downhill vehicle operation includes an electronically actuatable engine compression brake unit associated with an internal combustion engine, an electronically controllable turbocharger boost pressure adjustment device, electronically actuatable service brakes and a transmission including a number of automatically selectable gear ratios, wherein each of these components are coupled to a control computer. In accordance with one aspect of the present invention, the control computer is operable to detect a potential runaway vehicle condition and control any one or combination of engine compression brake activity, turbocharger boost pressure, service brake activity and automatic transmission shifting to thereby provide for a controlled descent down a negative grade and thereby prevent a runaway vehicle condition.

Abstract: A fuel system includes a pair of electronically controllable high pressure fuel pumps operable to supply high pressure fuel from a lower pressure fuel source to a high pressure fuel accumulator having a pressure sensor associated therewith. The fuel collection chamber feeds an electronically controllable valve operable to dispense the high pressure fuel to a fuel distribution unit supplying fuel to a number of fuel injectors. A control computer is provided for controlling the high pressure fuel pump and valve in response to requested fueling, engine speed and fuel pressure provided by the pressure sensor. The accumulator pressure signal is processed in accordance with the present invention for diagnosing erratic pressure sensor failures. The control computer is operable to compute error pressure values based on differences between peak accumulator pressure values and a target pressure value, and compute pressure error variance values based on subsets of the pressure error values.