3.12Detroit Diesel Engine Control Systems
Some generator sets equipped with Detroit Diesel engines use a DDEC/MDEC/ADEC system. Access the DDEC control box inside the generator set junction box to retrieve codes when performing routine maintenance or troubleshooting the engine.
Note: DDC/MTU engines with MDEC/ADEC use the 550 controller to display all engine fault code numbers. The engine operation manual provides the fault code description.
Use the following data for informational purposes only. Consult the engine literature for complete information regarding DDEC/MDEC/ADEC operation and troubleshooting. See List of Related Materials in the Introduction section. Contact an authorized service distributor/dealer for service or diagnostic equipment.
3.12.1 Features
The engine control system optimizes control of critical engine functions and protects against serious engine damage resulting from conditions such as the following:
DLow coolant level
DLow coolant pressure
DHigh coolant temperature
DLow oil pressure
DHigh oil temperature
The major components of the DDEC/MDEC/ADEC system include the electronic control module (ECM) and engine sensors. The DDEC control box is located in the generator set junction box.
3.12.2 DDEC Engine Diagnostics
The DDEC engine protection system monitors engine sensors and electronic components and recognizes system malfunctions. Critical faults light the check engine (CEL) and stop engine (SEL) lamps on the control box. ECM memory software logs malfunction codes. Consult the engine operation manual or engine service manual to identify the stored failure code. See Figure
1
1. Diagnostic request switch
Figure 3-22 DDEC Control Box
Access the stored codes in one of three ways:
DPlace the switch in the DIAGNOSTIC REQUEST position. The CEL or SEL flashes to identify the failure.
DUse a hand-held diagnostic data reader (DDR). Place the switch in the DIAGNOSTIC DATA READER position. Plug the DDR into the control box. The DDR displays the stored failure codes.
DUse a personal computer software package available from the manufacturer with a translator to access stored codes. Follow the instructions provided with the software.
Code Types
Active code. A code flashing on the SEL lamp indicates a fault currently exists.
Inactive code. A code flashing on the CEL lamp indicates a previous fault occurrence. The ECM memory stores inactive codes with time/date identification and the following information:
DFirst occurrence of each diagnostic code in engine operating hours.
DLast occurrence of each diagnostic code in engine operating hours.
DTotal time in seconds that the diagnostic code was active.
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