Lull 944E-42 Service Manual Download

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Electrical System

9.28

Model 644E-42/944E-42

Rev. 6/04

The text discusses each circuit and component, as well
as component function and replacement. Many of the
circuits have a separate diagram specific to that circuit’s
function which can be used for troubleshooting purposes.
Those same circuits also have their own troubleshooting
flow chart. Keep in mind that the various systems on the
vehicle include both electrical and hydraulic components.
What at first may appear to be an electrical problem may
turn out to be a hydraulic problem.

Note: All of the main electrical schematics in this
section are shown in the OFF position. The individual
circuit diagrams are shown in the ON position.

9.8.2

944E-42 ECM Diagnostic System

Advanced diagnostics are included to make this
Cummins engine straight forward to repair and service.
Diagnostic examination of a fault or maintenance
condition can occur through onboard or offboard
systems.

Onboard Diagnostics

• Extensive fault detection fault capability within

the ECM

• Flash-out of fault codes

• Engine function indicator light located on the left side

of the dash to indicate warning/stop

• Maintenance lamp

Offboard Diagnostics

• INSITE™, a Windows®-based reporting program

used as a service tool for this engine. It is used to
help troubleshoot and repair the engine. This tool is
capable of doing diagnostics and programming. This
tool is available from your local Cummins Distributor.
Call the Cummins Customer Assistance Center at
1-800-343-7357.

Onboard Diagnostics

a. Fault Detection

Faults are detected while the key switch is in the RUN
position, during the operation of the vehicle itself. If a fault
becomes active (currently detected) at this time, a fault is
logged in memory and a snapshot of engine parameters
is logged. In addition, certain faults may illuminate the
warning lamp (amber) or the stop lamp (red) depending
upon the severity of the active fault.

b. Flash-Out of Fault Codes

Fault flash-out mode can be entered through the use of a
diagnostic switch or the accelerator pedal. To enter the
fault flash-out mode, the key switch must be in the RUN
position with the engine not running.

When a diagnostic switch is used to enter the fault
flash-out mode, the ECM will automatically flash the first
fault code after the switch is turned to the RUN position.

The diagnostic increment/decrement is used to sequence
forward or backwards through the active faults.

To enter fault flash-out mode using the accelerator pedal,
fully depress and release the pedal 3 times. Once in
diagnostic mode, cycling the accelerator pedal will
sequence forward through the active faults. The following
graphic depicts the pattern of the fault code flash-out
scheme as indicated by the stop lamp.

Stop Lamp (1) - The stop lamp provides critical operator
messages. These messages require immediate and
decisive operator response. The stop lamp is also used
to diagnose flash-out fault codes.

Warning Lamp (2) - The warning lamp provides
important operator messages. These messages require
timely operator attention. The warning lamp is also used
to delineate diagnostic fault codes.

There is a laminated Wiring Diagram and Fault Code
Information Chart available from your local Cummins
Distributor. Call the Cummins Customer Assistance
Center at 1-800-343-7357.

Lull 944E-42, Service Manual

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