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Automatic Neutral Articulation Switch connections | |
This diagnostic code is associated with the automatic neutral articulation switch that is located on the left joystick handle. The switch supplies two, switch to ground type inputs to the Implement ECM. The ECM expects one of the two switch inputs to be grounded at all times. When the ECM detects that neither of the switch inputs is grounded, the ECM will activate an FMI 03 diagnostic code for voltage above normal.
The automatic neutral articulation switch is connected to ground at the Implement ECM and the Transmission Chassis ECM 5V sensor return (ECM ground). The switch must lose both grounds in order to disrupt the switch operation. The illustration above indicates the power and ground connections for the switch.
Note: For a schematic of the internal power and ground assignments for each individual component in the left joystick, refer to the Systems Operation, "Features" section of this manual.
Possible conditions that can cause this diagnostic code are listed:
- One or both of the input circuits of the switch are open in the machine harness.
- Both of the switch ground circuits are open in the machine harness.
- One or more of the switch inputs is shorted to a voltage source.
- The switch has failed.
- The ECM has failed. This is unlikely.
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, that all connections are secure and that all connections are 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.
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected.
Test Step 1. CHECK THE SWITCH CIRCUITS FOR AN OPEN
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the connector of the left joystick J2 from the machine harness connector.
- At the joystick connector J2, connect a jumper wire between the normally open (N/O) contact J2-3 (wire U744-OR(Orange)) and the normally closed (N/C) contact J2-3 (wire U745-PK(Pink)).
- Disconnect the machine harness connectors J1 and J2 from the Implement ECM.
- At the Implement ECM machine harness connector J2, measure the resistance between N/O contact J2-23 (wire U744-OR(Orange)) and N/C contact J2-28 (wire U745-PK(Pink)).
Expected Result:
The resistance measurement is less than 5Ω.
Results:
- OK. - The resistance measurement is less than 5Ω. The input circuits of the switch are not open in the machine harness. Proceed to Test Step 2.
- NOT OK. - The resistance measurement is greater than 5Ω. One of the switch circuits is open in the machine harness.
Repair: There is an open or a bad connection in the input wire of the switch U744-OR(Orange) or wire U745-PK(Pink). Refer to the complete Electrical System Schematic of the machine. Check the connectors that are in the switch circuits for loose connections or corroded connections. Repair the machine harness or replace the machine harness.
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Test Step 2. CHECK THE GROUND CIRCUITS FOR AN OPEN
The disconnect switch and the key start switch remain in the OFF position. The connector of the left joystick J2 remains disconnected from the machine harness. The Implement ECM connectors remain disconnected from the machine harness.
- Disconnect the connector for the left joystick J1 from the machine harness connector.
- Disconnect the connector for the machine harness J1 from the Transmission/Chassis ECM.
- At the connectors for the joystick J1 and J2, connect a jumper wire between the ground 1 contact J1-3 (wire L731-BR(Brown)) and ground 4 contact J3-3 (wire 998-BR(Brown)).
- Obtain a spare length of wire that is long enough to reach from the Transmission Chassis ECM to the cab of the machine. Connect one end of the spare wire to the Transmission/Chassis ECM return contact J1-21 (wire L731-BR(Brown)).
- At the machine harness connector of the Implement ECM J1, measure the resistance between return contact J1-21 (wire 998-BR(Brown)) and the end of the spare wire that is connected to the return contact of the Transmission/Chassis ECM J1-21 (wire L731-BR(Brown)).
Expected Result:
The resistance measurement is less than 5Ω.
Results:
- OK. - The resistance measurement is less than 5Ω. The ground circuits are not open in the machine harness. Proceed to Test Step 3.
- NOT OK. - The resistance measurement is greater than 5Ω. One of the switch ground circuits is open or has a bad connection in the machine harness.
Repair: Verify that the connection of the spare wire at the Transmission/Chassis ECM connector is a good connection and check the ground circuits again to verify that there is an open or bad connection present in the ground circuits.
If the resistance measurement is still greater than 5Ω, there is an open or a bad connection in ground wire 998-BR(Brown) or wire L731-BR(Brown).
NOTE: Both of the ground circuits must be open in order to cause this diagnostic code to activate, however, if one of the ground circuits is defective, the faulty circuit must be repaired before proceeding with this procedure.
Refer to the complete Electrical System Schematic of the machine. Check the connectors that are in the ground circuits for loose connections or corroded connections. Repair the machine harness or replace the machine harness.
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Test Step 3. CHECK THE HARNESS FOR A SHORT
The key start switch and the disconnect switch remain in the OFF position.
The harness connector J2 for the joystick and the ECM harness connectors remain disconnected.
- Connect the jumper wire that was used in the last test step between the joystick harness connector contact J2-3 (wire U744-OR(Orange)) and contact J2-4 (wire U745-PK(Pink)).
- At the Implement ECM machine harness connector J2, measure the resistance between contact J2-23 (wire U744-OR(Orange)) to all of the other contacts that are used in the J1 and J2 connectors for the ECM.
Expected Result:
Each resistance measurement is greater than 5kΩ.
Results:
- OK. - Each resistance measurement is greater than 5kΩ. The input circuits for the switch are not shorted in the machine harness. Proceed to Test Step 4.
- NOT OK. - One or more of the resistance measurements is less than 5kΩ.
Repair: There is a short in the machine harness. The short is between one of the switch circuits and the circuit with the low resistance measurement.
Check each switch input circuit individually for a short in order to determine which circuit is shorted to the circuit with the low resistance measurement.
Refer to the complete Electrical System Schematic of the machine. Check all of the connectors that are in the switch circuit. Ensure that all connections are clean, that all connections are secure and that all connections are in good condition.
For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace the machine harness.
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Test Step 4. CHECK THE SWITCH OPERATION
The connectors of the left joystick remain disconnected from the machine harness. The disconnect switch and the key start switch remain in the OFF position.
- At the joystick connectors, measure the resistance (continuity) between ground 1 contact J1-3 and the joystick N/O switch contact J2-3 when the switch is not depressed and when the switch is depressed.
- At the joystick connectors, measure the resistance (continuity) between ground 1 contact J1-3 and the joystick N/C switch contact J2-4 when the switch is not depressed and when the switch is depressed.
Expected Result:
When the switch is NOT depressed, the measurement results are as listed:
J1-3 (ground) to J2-3 (N/O) - No continuity (Open)
J1-3 (ground) to J2-4 (N/C) - Continuity (Closed)
When the switch IS depressed, the measurement results are as listed:
J1-3 (ground) to J2-3 (N/O) - Continuity (Closed)
J1-3 (ground) to J2-4 (N/C) - No continuity (Open)
Results:
- OK. - The continuity checks between ground contact J1-3 to the switch contacts are correct. The switch is operating correctly. Proceed to Test Step 5.
- NOT OK. - The continuity checks between the ground contact J1-3 to the switch contacts are not correct. The switch is not working correctly.
Repair: The automatic neutral articulation switch is not correct. Replace the joystick faceplate. Refer to Special Instruction, REHS7448, "Procedure To Remove And Replace The Left-Hand Joystick Push-Button Faceplate on M Series And M Series 2 Motor Graders". Verify that the operation of the joystick is correct before operating the machine.
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Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the contacts. Clean the contacts of any harness connectors that are disconnected.
- Reconnect all harness connectors.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 2147 FMI 03 diagnostic code is not active.
Expected Result:
The CID 2147 FMI 03 diagnostic code is active.
Results:
- OK. - The CID 2147 FMI 03 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation.
STOP
- NOT OK. - The CID 2147 FMI 03 diagnostic code is active. The diagnostic code has not been corrected.
Repair: Check the circuit again. Use the Caterpillar Electronic Technician (ET) service tool, if available, in order to perform a wiggle test on the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness.
If the cause of the active diagnostic code is not found, the ECM that has activated this diagnostic code may have failed.
Exit this procedure and perform this procedure again. If the cause of the failure is not found, contact the Technical Communicator (TC) of your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time.
If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
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