User's Manual

Table 16
Theft Deterrent Module ECM (MID 127)
DTC
Code Description System Response
168-00 Electrical System Voltage : High
168-01 Electrical System Voltage : Low
The electrical power supply connections are the
connections between the alternator and battery that
power the control modules.
The diagnostic code should be ACTIVE only if the
engine is running.
Possible causes for an FMI 00 diagnostic code
are:
• The alternator is producing too much voltage.
• A charging system component has failed.
• The ECM has failed. A failure of the ECM is
unlikely.
Possible causes for an FMI 01 diagnostic code
are:
• The wiring in the machine harness has failed.
• A poor connection in the ground circuit.
• A charging system component has failed.
• The alternator or charging system has failed.
• The ECM has failed. A failure of the ECM is
unlikely.
Note: The locations of the components of the MSS
will vary between machines. If the MSS was installed
by a Caterpillar dealer, consult the installation
instructions for component locations. If the MSS was
an attachment that was installed at the factory,
consult the electrical schematic for that machine.
Diagnostic Trouble Code
Procedure
Note: Prior to beginning this procedure, inspect the
harness connectors that are involved in this circuit.
Poor connections can often be the cause of a
problem in an electrical circuit. Verify that all
connections in the circuit are clean, secure, and in
good condition. Ensure that the Charging System is
functioning properly. Check the wiring harness for
pinch points or abrasions. Look for and repair areas
that indicate wires are exposed. If a problem with a
connection is found, correct the problem and verify
that the diagnostic code is active before performing a
troubleshooting procedure.
1. Identify the active FMI code associated with the
components.
2. Determine which code is present and use the list
below to determine which procedure to follow.
• FMI 00 diagnostic code, proceed to Table 17 .
• FMI 01 diagnostic code, proceed to Table 18 .
UENR7061 47
Circuit Tests