User's Manual

Illustration 19 g03863156
20. On the main menu bar, select “Service” and then
“ECM Date/Time” . Verify that correct date, time,
and time zone are displayed for your location.
Click on the “Change” button to adjust the settings.
21. Check the bypass times to ensure that the times
are set correctly.
22. The ECM replacement procedure is now
complete. You may choose to remove the two pre-
installed master access level keys from the key
list. To remove these keys, select “Service” and
then “Security Management” from the menu bar.
The list of keys will be displayed. In the
“Description” field, located and highlight (one at a
time) keys M1 and M2. Click on the “Delete”
button. Confirm the “Are you sure.” by clicking
“OK” .
i06229371
Connector Contact
Description
SMCS Code: 1408-CY; 7553-WW
The decisions that the ECM makes are based on
input data information and programming parameters
that have been flashed to the ECM memory. After the
ECM receives the input information, the ECM
determines the correct response and sends an output
signal to the appropriate device. The internal input
and output circuits of the ECM are connected to the
machine wiring harness by two contact connectors
(J1 and J2).
Note: The ECM is not serviceable. If the ECM is
damaged, the ECM must be replaced. The ECM
failure is unlikely. If the ECM failure is suspected,
contact the Technical Communicator at a local
dealership for possible consultation with Caterpillar
before replacing the ECM. Replace the ECM only
after all of the other possible causes of a particular
problem have been investigated.
ECM Pull Up Voltage
To aid in diagnostics of certain electrical circuits, an
internal “pull up voltage” is connected to the ECM
switch and sensor signal input contacts. An above
normal voltage is internally connected to the ECM
signal input circuit through a resistor.
During normal operation, the switch or sensor signal
will hold the circuit low or at a certain signal
amplitude. When circuit conditions such as a loss of
power to the component, a disconnection, or an open
circuit, the ECM circuit will be puled high by the pull
up voltage. The pull up voltage will result in an above
normal voltage condition at the ECM contact. As a
result, the ECM will activate an FMI 03 (voltage
above normal) diagnostic code for the affected
circuit.
The types of ECM input circuits that have pull up
voltage present are:
• Pulse Width Modulated (PWM) sensor input
circuits
• Switch to ground switch input circuits
• Active analog (voltage) input signal circuits
• Passive analog (resistance) input signal circuits
ECM Pull Down Voltage
In order to aid in diagnostics of electrical circuits
controlled by the ECM, an internal “pull down
voltage” is connected to the ECM switch to battery
input circuits.
During normal operation, the switch contacts that are
allowing the connection to a voltage source will hold
the circuit high. When conditions like a loss of power
to the switch supply, switch circuit disconnection, or
an open circuit, will allow the ECM circuit to be pulled
low by the pull down voltage. The pull down voltage
will result in a below normal voltage condition at the
ECM contact. As a result, the ECM will activate an
FMI 04 (voltage below normal) diagnostic code for
the affected circuit.
Inputs
The machine has several different types of input
devices. The ECM receives machine status
information from the input devices. The ECM
determines the correct output action that is needed in
order to control machine operations based on
memory and software parameters. The machine
utilizes the following types of inputs: switch type and
sensor type.
Switches provide signals to the switch inputs of the
ECM. The possible outputs of a switch are listed: an
open signal, a grounded signal and + battery signal.
UENR7061 59
Service