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TP-6200 10/12152 Section 3 Scheduled Maintenance
3.12 Detroit D iesel 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:
D Low coolant level
D Low coolant pressure
D High coolant temperature
D Low oil pressure
D High 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 3-22 for the DDEC control box features.
A-343591-C
1. Diagnostic request switch
1
Figure 3-22 DDEC Control Box
Access the stored codes in one of three ways:
D Place the switch in the DIAGNOSTIC REQUEST
position. The CEL or SEL flashes to identify the
failure.
D Use 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.
D Use 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:
D First occurrence of each diagnostic code in engine
operating hours.
D Last occurrence of each diagnostic code in engine
operating hours.
D Total time in seconds that the diagnostic code was
active.