INTRODUCTION TO LOGIC TREE TROUBLESHOOTING (CONT). -726280198

TM 9-2320-364-20-1

2-12. INTRODUCTION TO LOGIC TREE TROUBLESHOOTING (CONT).

(4)

CEL - Check Engine Light: Mounted on the dash panel. Has two functions:

(a)

Serves as a warning lamp to tell the driver that a problem has occurred and that the truck should be

taken in for service as soon as possible.

(b)

Serves as a light bulb check and system check. The Check Engine Light (CEL) will come on for

about 5 seconds when the ENGINE switch is turned ON. If the CEL remains on, the

self-diagnostics system has detected a problem. If the problem goes away, the light will go out, but

the HISTORICAL trouble code will be stored in the DDEC ECM memory.

(5)

CGL - Check Gages Light: Mounted on the dash, it lights to warn the driver when a potential engine

damaging condition has been detected (low oil pressure, low coolant, or engine over temperature). As a

light bulb check, the CGL will come on for about 5 seconds when ignition switch is placed in the ON

position.

(6)

CKT - Circuit.

(7)

COM - Common.

(8)

DCA - Diagnostic Connector Assembly: An electrical harness on the truck which allows the STE/ICE-R

to be powered and to make measurements of key truck signals from a single connection. In addition to

many basic electrical signals such as starter voltage and current, it includes engine speed and fuel return

pressure. The STE/ICE-R can make TK measurements while connected to the DCA.

(9)

DDEC II - The Detroit Diesel Electronic Controls, second generation.

(10)

DDEC III - The Detroit Diesel Electronic Controls, third generation.

(10.1) DDEC IV - The Detroit Diesel Electronic Controls, fourth generation.

(11)

DDL - Diagnostic Data Link: The lines (wires) over which the DDEC ECM communicates information

to be read by a Diagnostic Data Reader.

(12)

DDR - Diagnostic Data Reader: The hand-held tool used for troubleshooting with the DDEC (DDR or

PRO-LINK 9000).

(13)

Diagnostics - Troubleshooting by following an exact procedure.

(14)

DL+ - Data Link, positive side. Used for communications to the Diagnostic Data Reader, as well as other

applications.

(15)

DL- - Data Link, negative side. Used for communications to the Diagnostic Data Reader, as well as

other applications.

(16)

DREQ - Diagnostic Request Terminal: The pin on the DDL connector which must be grounded to obtain

diagnostic codes (pin M).

(17)

ECM - Electronic Control Module: The brains of DDEC II and DDEC III/IV. It receives input from the

DDEC II and DDEC III/IV sensors and switches, calculates injector firing times and duration (using a

built-in computer) and fires the injectors at the appropriate times. System operates on 12 vdc with 5 vdc

input to sensors and switches back to ECM.

(18)

EEPROM - Electronically Erasable Programmable Read Only Memory: Contains the engine calibration.

(19)

EFPA - Electronic Foot Pedal Assembly.

(20)

Erratic - Intermittent.

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