The DDEC III/IV ECM receives electronic inputs from sensors on the engine and vehicle, and uses the information to control engine operation. Fuel is controlled by DDEC. See Figure 6.
Portable equipment facilitates access to diagnostic capabilities of DDEC III/IV’s. The Diagnostic Data Reader (DDR) requests and receives engine data and diagnostic codes. This equipment provides many unique capabilities including cylinder cutout, printer output, and data snapshot. The DDR also provides limited programming capability.