TM 9-2320-363-20-1
Section 2
BASIC KNOWLEDGE REQUIRED (Cont’d.)
D. EXPLANATION OF ABBREVIATIONS/TERMS
AID
Analog to Digital: The computer inside the ECM uses an A/D converter is convert a sensor voltage into a
number which the computer can work with.
BAT
- Battery
BOI
- Beginning of injection: The number of crank angle degrees. before TOP Dead Center. that the ECM is
requesting the injectors be turned on.
CCM
- Crankcase Monitor Sensor: Monitors Crankcase Pressure.
CEL
-
"Check Engine Light: typically mounted on the instrument panel. It has two functions:
l It is used as a warning lamp to tell the driver that a problem has occurred and that the vehicle should be
taken in for service as soon as possible.
l it is used by the technician to read out "trouble codes" to help diagnose System problems.
As a light bulb check and system check the "Check Engine”’ light will come on for about 5 seconds when the
ignition IS turned "ON". If the CEL remains on. the self-diagnostic system has detected a problem. If the
problem goes away the light will go out. but a trouble code will be stored in the ECM.
CKT
- Circuit
CLS
- CooIant Level Sensor: Monitors coolant level at the radiator tank top
CP
-
Crank Position: An ECM output generated anytime an SRS signal occurs ( at the first cylinder)
COM
- Common
CTS
- Coolant Temperature Sensor: Can be used in place of the Oil Temperature Sensor for measuring engine .
temperature (assuming DDEC II has been set-up for the CTS).
DDEC II - 2nd generation Detroit Diesel Electronic Controls
DDL
- Diagnostic Data Link: The lines (wires) over which the ECM communicates information can be read by a
Diagnostic Data Reader. -
DDR
- Diagnostic Data Reader: The hand-held tool for use in troubleshooting DDEC PRO-LINK.
DL+
- Data Link, positive side. Used for communications to the Diagnostic Data Reader, as well as other
applications.
DL
- Data Link, negative side.
DL2+
- Proprietary Data Link. positive side. It’s main function is for dual engine
applications where two ECM’S
must talk to each other.
DL2-
- Proprietary Data Link, negative side.
DREQ
- Diagnostic Request Terminal: The pin on the DDL connector which must be grounded to obtain diagnostic
codes (pin M).
ECM
- Electronic Control Module The brains of DDEC II It reads the DDEC II sensors and switches. calculates
injector flrmg times and duration (using a built-in computer). and fires the
injectors at the appropriate times.
EEPROM - Electrically Erasable Programmable Read Only Memory. Contains the en gine calibration.
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