966M and 972M Wheel Loaders Caterpillar

Relay - Test

Usage:

972M A78

Implement ECM

The following is a list of codes associated with the relays related to the Implement ECM.

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Table 1
Implement ECM (MID 82)
DTC ⁽¹⁾	Code Description	System Response
2909-3	Rear Wiper Activation Relay : Voltage Above Normal	When the Rear Wiper Activation Relay is Faulted, the Rear Wiper will be rendered non-functional.
2909-5	Rear Wiper Activation Relay : Current Below Normal	When the Rear Wiper Activation Relay is Faulted, the Rear Wiper will be rendered non-functional.
2909-6	Rear Wiper Activation Relay : Current Above Normal	When the Rear Wiper Activation Relay is Faulted, the Rear Wiper will be rendered non-functional.
2910-3	Front Wiper Activation Relay : Voltage Above Normal	When the Front Wiper Activation Relay is Faulted, the Front Wiper will be rendered non-functional.
2910-5	Front Wiper Activation Relay : Current Below Normal	When the Front Wiper Activation Relay is Faulted, the Front Wiper will be rendered non-functional.
2910-6	Front Wiper Activation Relay : Current Above Normal	When the Front Wiper Activation Relay is Faulted, the Front Wiper will be rendered non-functional.
2911-3	Rear Wiper Speed Control Relay : Voltage Above Normal	When the Rear Wiper Speed Control Relay is Faulted, the Rear Wiper will be rendered non-functional.
2911-5	Rear Wiper Speed Control Relay : Current Below Normal	When the Rear Wiper Speed Control Relay is Faulted, the Rear Wiper will be rendered non-functional.
2911-6	Rear Wiper Speed Control Relay : Current Above Normal	When the Rear Wiper Speed Control Relay is Faulted, the Rear Wiper will be rendered non-functional.
2912-3	Front Wiper Speed Control Relay : Voltage Above Normal	When the Front Wiper Speed Control Relay is Faulted, the Front Wiper will be rendered non-functional.
2912-5	Front Wiper Speed Control Relay : Current Below Normal	When the Front Wiper Speed Control Relay is Faulted, the Front Wiper will be rendered non-functional.
2912-6	Front Wiper Speed Control Relay : Current Above Normal	When the Front Wiper Speed Control Relay is Faulted, the Front Wiper will be rendered non-functional
3064-3	Front Long Range Work Light #1 Relay : Voltage Above Normal	When the Front Long Range Work Light #1 Relay is Faulted, the Optional Attachment Front Work Lights will be rendered non-functional.
3064-5	Front Long Range Work Light #1 Relay : Current Below Normal	When the Front Long Range Work Light #1 Relay is Faulted, the Optional Attachment Front Work Lights will be rendered non-functional
3064-6	Front Long Range Work Light #1 Relay : Current Above Normal	When the Front Long Range Work Light #1 Relay is Faulted, the Optional Attachment Front Work Lights will be rendered non-functional
3065-3	Rear Long Range Work Light #1 Relay : Voltage Above Normal	When the Rear Long Range Work Light #1 Relay is Faulted, the Optional Attachment Rear Work Lights will be rendered non-functional.
3065-5	Rear Long Range Work Light #1 Relay : Current Below Normal	When the Rear Long Range Work Light #1 Relay is Faulted, the Optional Attachment Rear Work Lights will be rendered non-functional.
3065-6	Rear Long Range Work Light #1 Relay : Current Above Normal	When the Rear Long Range Work Light #1 Relay is Faulted, the Optional Attachment Rear Work Lights will be rendered non-functional.
3071-3	High Beam Light Relay : Voltage Above Normal	When the High Beam Light Relay is Faulted, the High Beam Roading Lights will be rendered non-functional.
3071-5	High Beam Light Relay : Current Below Normal	When the High Beam Light Relay is Faulted, the High Beam Roading Lights will be rendered non-functional.
3071-6	High Beam Light Relay : Current Above Normal	When the High Beam Light Relay is Faulted, the High Beam Roading Lights will be rendered non-functional.
3467-3	Main Power Relay : Voltage Above Normal	Machine electrical systems are disabled.
3467-5	Main Power Relay : Current Below Normal	Machine electrical systems are disabled.
3467-6	Main Power Relay : Current Above Normal	Machine electrical systems are disabled.
3470-3	Machine Power Distribution Relay : Voltage Above Normal	Machine electrical systems are disabled.
3470-5	Machine Power Distribution Relay : Current Below Normal	Machine electrical systems are disabled.
3470-6	Machine Power Distribution Relay : Current Above Normal	Machine electrical systems are disabled.
7802-3	Beacon: Voltage Above Normal	When the Beacon Relay is Faulted, the Beacon Light will be rendered non-functional.
7802-5	Beacon: Current Below Normal	When the Beacon Relay is Faulted, the Beacon Light will be rendered non-functional.
7802-6	Beacon: Current Above Normal	When the Beacon Relay is Faulted, the Beacon Light will be rendered non-functional.

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⁽¹⁾	Diagnostic Codes for components that are connected to the Relay Driver Module are communicated to the Implement ECM via CAN Data Link.

Possible Causes for an FMI 3 Diagnostic code are:

The relay has failed.
The energize circuit of the relay is shorted to the +battery circuit.
The indicator lamp has failed.
The ECM has failed. ECM failure is unlikely.

Possible Causes for an FMI 5 Diagnostic code are:

The relay has failed.
There is an open in the circuit.
The ECM has failed. ECM failure is unlikely.

Possible Causes for an FMI 6 Diagnostic code are:

The energizer circuit of the relay is shorted to ground.
The relay has failed.
The ECM has failed. ECM failure is unlikely.

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Illustration 1	g03595519

Note: The diagrams above are simplified schematics of the relays and the relay connections for the Implement ECM. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, KENR5564 for the complete schematic.

Transmission ECM

The following is a list of codes associated with the relays related to the Transmission ECM.

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Table 2
Transmission ECM (MID 81)
DTC	Code Description	System Response
420-3	Secondary Steering Relay : Voltage Above Normal	If this DTC is active, the Secondary Steering Pump (if equipped) will not turn on. An E560 Event “Secondary Steering Pump Not Responding to Command” will also occur at startup, after the automatic secondary steering pump test is performed.
420-5	Secondary Steering Relay : Current Below Normal	If this DTC is active, the Secondary Steering Pump (if equipped) will not turn on. An E560 Event “Secondary Steering Pump Not Responding to Command” will also occur at startup, after the automatic secondary steering pump test is performed.
420-6	Secondary Steering Relay : Current Above Normal	If this DTC is active, the Secondary Steering Pump (if equipped) will not turn on. An E560 Event “Secondary Steering Pump Not Responding to Command” will also occur at startup, after the automatic secondary steering pump test is performed.
444-3	Starter Motor Relay : Voltage Above Normal	Starter Motor is disabled.
444-5	Starter Motor Relay : Current Below Normal	Starter Motor is disabled.
444-6	Starter Motor Relay : Current Above Normal	Starter Motor is disabled.

Possible Causes for an FMI 3 Diagnostic code are:

The relay has failed.
The energize circuit of the relay is shorted to the +battery circuit.
The indicator lamp has failed.
The ECM has failed. ECM failure is unlikely.

Possible Causes for an FMI 5 Diagnostic code are:

The relay has failed.
There is an open in the circuit.
The ECM has failed. ECM failure is unlikely.

Possible Causes for an FMI 6 Diagnostic code are:

The energizer circuit of the relay is shorted to ground.
The relay has failed.
The ECM has failed. ECM failure is unlikely.

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Illustration 2	g03595518

Note: The diagrams above are simplified schematics of the relays and the relay connections for the Transmission ECM. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, KENR5564 for the complete schematic.

Troubleshooting Procedure

Note: Prior to beginning 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.

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Table 3
Troubleshooting Test Steps	Values	Results
1. Identify Active FMI Code Associated With Relay Circuit	Code present.	FMI 3 diagnostic code, proceed to Test Step 2. FMI 5 diagnostic code, proceed to Test Step 3. FMI 6 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Machine Harness For A Short A. Turn key start switch and disconnect switch OFF. B. Disconnect harness connection at relay. C. If relay connected to ECM, disconnect J1 and J2 connectors from ECM. If relay connected to Switch Panel, disconnect all Switch Panel connectors. D. Measure resistance of relay signal contact to all J1 and J2 connectors, if relay is wired directly to Transmission ECM. If relay is wired directly to switch panel, measure resistance of relay contact to all switch panel connectors.	Each reading is greater than 5K ohms.	OK: All resistance measurements are greater than 5K ohms. Proceed to Test Step 7. NOT OK: One or more readings are less than 5 ohms. 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 ohms but less than 5K ohms would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K ohms would indicate an open in the circuit. STOP
Begin Process For FMI 5 Troubleshooting HERE
3. Check The Relay A. Turn the key start switch and the disconnect switch OFF. B. Remove the relay. C. Place a jumper wire between the signal contact and the return contact of the relay. D. Turn the key start switch and the disconnect switch ON. Do not start the engine. E. As the jumper is removed and connected to the contacts, observe any code change.	The code changes to FMI 6 after the jumper wire is installed.	OK: The circuit is correct. The relay has failed. Repair: Replace the relay. After replacement of the relay, confirm the diagnostic code is not active. STOP NOT OK: The diagnostic code remains active. Proceed to Test Step 4.
4. Check The Machine Harness For An Open A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the harness connectors from the ECM. C. The jumper wire remains installed. D. At the machine harness connector for the ECM, measure the resistance at the ECM contacts for the relay.	Each reading is less than 5 ohms .	OK: The reading is less than 5 ohms, the harness is correct. Proceed to Test Step 7. NOT OK: The reading is greater than 5K ohms . Circuit open in machine harness. Repair: The open is in the wire for the relay signal or the return wire for the relay. Repair or replace the machine harness. Note: A resistance that is greater than 5 ohms but less than 5K ohms would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K ohms would indicate an open in the circuit. STOP
Begin Process For FMI 6 Troubleshooting HERE
5. Check The Indicator Lamp A. Key start switch and disconnect switch OFF. B. Disconnect the relay from the wiring harness. C. Review the electrical schematic (above) to identify the input and output wires from the coil of the relay. D. Use a multimeter to measure the resistance across the coil of the relay.	The resistance of the coil is less than 50 ohms.	OK: The resistance is less than 50 ohms . Proceed to Test Step 6.. NOT OK: The resistance is greater than 5K ohms. The relay has failed Repair: Replace the relay. Note: After the relay is replaced, confirm diagnostic code is no longer active. Note: A resistance that is greater than 50 ohms but less than 5K ohms would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K ohms would indicate an open in the circuit. STOP
6. Check Machine Harness For A Short To Ground A. Machine harness remains disconnected from relay. B. Turn key start switch and disconnect switch OFF. C. Disconnect harness connectors from the ECM (or switch panel). D. At harness connector for ECM, measure resistance between lamp relay contact and all ground contacts.	Each reading greater than 5K ohms.	OK: All machine harness readings are correct. Proceed to Test Step 7. NOT OK: A short circuit exists in the machine harness. Repair: The short is between the lamp contact for the relay and the circuit with the low resistance. Repair or replace the machine harness. Note: A resistance that is greater than 5 ohms but less than 5K ohms would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K ohms would indicate an open in the circuit. STOP
7. Check If The Diagnostic Code Remains A. Turn key switch and disconnect switch ON. B. Clear all diagnostic codes. C. Operate the machine. D. Stop machine and engage the parking brake. E. Check if diagnostic code for the relay is active.	Code for relay is NO longer present.	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. Resume machine operation. STOP NOT OK: Diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM (or Switch Panel) may require replacement. Repair: Prior to replacing this component, always contact the Technical Communication at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. Follow the steps in Troubleshooting , "ECM - Replace" if the ECM needs to be replaced. STOP