966H, 972H and 980H Wheel Loaders Power Train Electronic Control System Caterpillar

Alarm - Test

Usage:

966H BJ6

The following is a list of codes that are associated with the backup alarm circuit of the machine.

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Table 1
Transmission ECM (MID 81)
DTC	Code Description	System Response
637-3	Backup Alarm : Voltage Above Normal	Alarm will sound continuously
637-5	Backup Alarm : Current Below Normal	Alarm will not sound
637-6	Backup Alarm : Current Above Normal	Alarm will sound continuously

Before performing this procedure, inspect the harness connectors that are involved in the 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. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.

Possible Causes for an FMI 3 Diagnostic code are:

The return circuit is open.
The signal circuit is open or the alarm is disconnected.
The signal circuit is shorted to the +battery.
The alarm has failed.
The monitor has failed. This condition is unlikely.

Possible Causes for an FMI 5 Diagnostic code are:

The alarm has failed
The signal circuit for the alarm is shorted to ground
The monitor has failed. A failure of the monitor is unlikely.

Possible Causes for an FMI 6 Diagnostic code are:

The energize circuit of the backup alarm is shorted to ground.
The backup alarm has failed.
The ECM has failed. This condition is unlikely.

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Illustration 1	g03376179
Schematic of Action Alarm

Note: The diagram above is a simplified schematics of the connections for the backup alarm. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR1687 for the complete schematic of 966H and 972H Wheel Loaders Electrical System. Refer to the latest revision of Electrical Schematic, UENR1699 for the complete schematic of 980H Wheel Loaders Electrical System.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Identify The Active DTC Code Associated With The Suspect Circuit	Code present.	FMI 3 diagnostic code: proceed to Test Step 2. FMI 5 diagnostic code: proceed to Test Step 5. FMI 6 diagnostic code: proceed to Test Step 8.
Begin Process For DTC- 3 Troubleshooting HERE
2. Check The Alarm A. Turn the key start switch and the disconnect switch to the OFF position. B. Disconnect the alarm from the harness. C. Use jumpers to connect the respective terminals of the alarm to +battery and ground. D. Turn the key start switch and the disconnect switch to the ON position.	The alarm sounds	OK - The alarm sounds. Proceed to Test Step 3. NOT OK - The alarm does not sound. Repair: Replace the alarm. STOP
3. Check For An Open In The Alarm Circuit A. The key start switch and disconnect switch remain in the OFF position. B. The harness connector remains disconnected from the alarm. C. Disconnect the J1 and J2 connectors from the monitor. D. At the harness connector for the alarm, install a jumper wire. E. At the harness connector for the monitor measure the resistance at the contacts for the alarm.	The resistance reading is less than 5 Ω.	OK - The resistance is less than 5 Ω. Proceed to Test Step 4. NOT OK - The resistance is greater than 5K Ω. Repair: Either the signal or the return circuit wire is open. Repair or replace the harness. STOP
4. Check The Signal Circuit For A Short. A. The disconnect switch and the key start switch remain in the OFF position. B. The harness connectors J1 and J2 remain disconnected from the monitor. C. Remove the jumper wire that was installed during the previous Test Step.. D. At the monitor harness connectors measure the resistance between the positive connector and all J1 and J2 contacts.	Each resistance measurement is greater than 5K Ω.	OK - Each measurement is greater than 5K Ω. Proceed to Test Step 9. NOT OK - A resistance measurement is less than 5K Ω. Repair: A short exists between the signal circuit and the circuit with the low resistance measurement. Repair or replace the machine harness.
Begin Process For DTC-5 Troubleshooting HERE
5. Check The Alarm A. Turn key start switch and disconnect switch ON. B. Ensure that the diagnostic code is active. C. Disconnect alarm from machine harness. D. Observe the status of the diagnostic code.	DTC changes from a DTC-5 to a DTC-3.	OK - DTC changes from a DTC-5 to a DTC-3. Repair: Replace the alarm. After alarm replacement, confirm code is not active. NOT OK - The DTC-5 remains active. Proceed to Test Step 6.
6. Check The Wiring Harness Of The Alarm For A Short To Ground A. Turn the key start switch and the disconnect switch OFF. B. Disconnect machine harness connection at alarm. C. Disconnect machine harness connections at alarm. D. At the machine harness connector for the alarm, measure resistance from the signal contact of machine harness to all possible sources of ground. Measure resistance to all contacts of machine harness connectors for the monitor.	Each resistance measurement is greater than 5K Ω.	OK - Each resistance measurement is greater than 5K Ω. Proceed to Test Step 7. NOT OK - One or more of the readings are less than 5 Ω. Repair: A short exists between the signal contact and the circuit with the low resistance. Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
Begin Process For DTC-6 Troubleshooting HERE
8. Check The Backup Alarm A. Turn the disconnect switch and the key start switch to the ON position. Do not start the engine. B. Observe the status of the diagnostic code. B. Disconnect the alarm from the machine harness.	The DTC- 6 diagnostic code changes to a DTC-5.	OK - The DTC- 6 diagnostic code changes to a DTC-5. The circuit is correct The backup alarm has failed. Repair: Replace the alarm. NOT OK - The DTC- 6 remains active. Proceed to Test Step 8.
8. Check The Energize Circuit Of The Backup Alarm For A Short To Ground A. The machine harness remains disconnected from the alarm. B. Turn the key start switch and the disconnect switch OFF. C. Disconnect the harness connectors from the ECM. D. At the harness connector for the ECM, measure the resistance between the alarm signal contact and all ground contacts.	Each resistance measurement is greater than 5K Ω.	OK - Each resistance measurement is greater than 5K Ω. Proceed to Test Step 9. NOT OK - One or more of the resistance measurements are less than 5 Ω. A short circuit exists in the machine harness. Repair: A short circuit exists between the wire for the signal wire of the alarm and the circuit with the low resistance. Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
9. Check If The Diagnostic Code Remains A. Turn the key start switch and the disconnect switch ON. B. Clear all diagnostic codes. C. Operate the machine. D. Stop the machine and engage safety lock lever. E. Check if diagnostic code for the alarm is active.	DTC Code is no longer active.	OK - Diagnostic code does not exist at this time. Initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Repair: Resume normal machine operation. NOT OK - Diagnostic trouble code has not been corrected. Repair: If the diagnostic code has not been corrected, the ECM may have failed. Prior to replacing the ECM, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Troubleshooting, "Electronic Control Module (ECM) - Replace". STOP.