MSS3s Machine Security System Caterpillar

Electrical Power Supply - Test

Usage:

120G 11W

Theft Deterrent Module ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the electrical power supply for the ECM.

Show/hide table

Table 1
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.

Identify the active FMI code associated with the components.
Determine which code is present and use the list below to determine which procedure to follow.

FMI 00 diagnostic code, proceed to Table 2.
FMI 01 diagnostic code, proceed to Table 3.

Show/hide table

Table 2
FMI 00 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. CHECK THE BATTERY VOLTAGE A. Start the engine and run the engine at high idle for several minutes. Make sure that no battery charger is connected to the engine. B. Measure the battery voltage at the battery posts.	The battery voltage should be less than 32.5 VDC for a 24V system, and less than 16 VDC for a 12V system.	OK - The battery voltage is correct. Proceed to Test Step 2. NOT OK - The battery voltage is too high. Repair: The charging system is not correct. Check the charging system. See Special Instruction, REHS0354, "Charging System Troubleshooting". STOP.
2. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE A. Stop the engine. Make sure that no battery charger is connected to the engine. B. Remove the connector from the ECM. Inspect the contacts and clean the contacts of the harness connectors. C. Reconnect all harness connectors. D. Turn the key start switch to the ON position. E. Use the Caterpillar Electronic Technician and clear all inactive diagnostic codes. F. Operate the machine. G. Determine if CID 0168 FMI 00 is present.	Each resistance is less than 5.0 Ω.	OK - CID 0168 FMI 00 is present. Repair: The problem has not been corrected. A failure of the ECM is unlikely. Perform the previous Test Steps again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "ECM - Replace". STOP. NOT OK - CID 0168 FMI 00 is not present. Repair: the diagnostic code is NOT present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation. STOP.

Show/hide table

Table 3
FMI 01 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. CHECK THE BATTERY VOLTAGE A. Start the engine and run the engine at high idle for several minutes. Make sure that no battery charger is connected to the engine. B. Measure the battery voltage at the battery posts.	The battery voltage should be greater than 9 VDC for a 12V system. The battery voltage should be greater than 21.3 VDC for a 24V system.	OK - The battery voltage is good. Proceed to Test Step 2. NOT OK - The battery voltage is too low. Repair: The charging system is not correct. Check the charging system. See Special Instruction, REHS0354, "Charging System Troubleshooting". STOP.
2. CHECK THE SYSTEM VOLTAGE AT THE ECM A. The engine must still be running at high idle. B.DO NOT DISCONNECT the machine harness from the ECM. At the connector of the ECM, prepare to make a voltage measurement by using the 7X-1710 Multimeter Probe. C. At the machine harness for the ECM, insert the probe into the back of connector. Measure the voltage (VDC) between pin 1 and pin 26.	The battery voltage should be greater than 9 VDC for a 12V system. The battery voltage should be greater than 21.3 VDC for a 24V system.	OK - The battery voltage is correct. Proceed to Test Step 3. NOT OK -The battery voltage is too low. Repair:The machine harness is not correct. Repair the machine harness or replace the machine harness. STOP.
3. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE A. Remove the connector from the ECM. Inspect the contacts and clean the contacts of the harness connectors. B. Reconnect all harness connectors. C. Turn the key start switch to the ON position. D. Clear all inactive diagnostic codes. E. Operate the machine. F. Determine if CID 0168 FMI 01 is present.	CID 0168 FMI 01 is present.	OK - ECID 0168 FMI 01 is present. Repair:The problem has not been corrected. A failure of the ECM is unlikely. Perform the previous Test Steps again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "ECM - Replace". STOP. NOT OK - CID 0168 FMI 01 is not present. Repair:The diagnostic code is NOT present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation. STOP.