950M and 962M Wheel Loaders Caterpillar


Solenoid Return - Test

Usage:

962M EJB


Implement ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the solenoid return circuits of the machine.

Table 1
Implement ECM (MID 82) 
DTC  Code Description  System Response 
1674-3  Solenoid Return #1: Voltage Above Normal  The machine will transition to the secondary steering system. This return is the return for the Left Primary Steering Solenoid and the Right Primary Steering Solenoid.  
1674-4  Solenoid Return #1: Voltage Below Normal  The machine will transition to the secondary steering system. This return is the return for the Left Primary Steering Solenoid and the Right Primary Steering Solenoid.  
1674-5  Solenoid Return #1: Current Below Normal  The machine will transition to the secondary steering system. This return is the return for the Left Primary Steering Solenoid and the Right Primary Steering Solenoid.  

The solenoid is used to shutoff, release, distribute, or mix fluids on the machine. Generally, multiple solenoids are located together on a manifold. The solenoid converts electrical energy into magnetic energy, moving a spool located inside the housing of the valve. A spring is used to hold the spool in position until the solenoid is energized.

The magnetic force that acts on the valve spool is created when a coil inside the solenoid is energized.

Possible causes for an FMI 3 Diagnostic code are:

  • The harness is shorted.

  • The Implement ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 4 Diagnostic code are:

  • There is an open in the circuit.

  • The solenoid has failed.

  • The Implement ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 5 Diagnostic code are:

  • There is an open in the circuit.

  • The solenoid has failed.

  • The ECM has failed. A failure of the ECM is unlikely.


Illustration 1g03632364
Schematic of the Solenoid Return circuits

Note: The diagram above is a simplified schematic of the connections for the solenoid return circuits. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR3117 for the complete schematic.

Transmission ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the solenoid return circuits of the machine.

Table 2
Transmission ECM (MID 81) 
DTC  Code Description  System Response 
1674-3  Solenoid Return #1: Voltage Above Normal  This return is the return for the Left Secondary Steering Solenoid and the Right Secondary Steering Solenoid.  
1674-4  Solenoid Return #1: Voltage Below Normal  This return is the return for the Left Secondary Steering Solenoid and the Right Secondary Steering Solenoid.  
1674-5  Solenoid Return #1: Current Below Normal  This return is the return for the Left Secondary Steering Solenoid and the Right Secondary Steering Solenoid.  

The solenoid is used to shutoff, release, distribute, or mix fluids on the machine. Generally, multiple solenoids are located together on a manifold. The solenoid converts electrical energy into magnetic energy, moving a spool located inside the housing of the valve. A spring is used to hold the spool in position until the solenoid is energized.

The magnetic force that acts on the valve spool is created when a coil inside the solenoid is energized.

Possible causes for an FMI 3 Diagnostic code are:

  • The harness is shorted.

  • The Implement ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 4 Diagnostic code are:

  • There is an open in the circuit.

  • The solenoid has failed.

  • The Implement ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 5 Diagnostic code are:

  • There is an open in the circuit.

  • The solenoid has failed.

  • The ECM has failed. A failure of the ECM is unlikely.


Illustration 2g03646387
Schematic of the Solenoid Return circuits

Note: The diagram above is a simplified schematic of the connections for the solenoid return circuits. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR3117 for the complete schematic.

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. 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.

Table 3
Troubleshooting Test Steps  Values  Results 
1. Identify Active FMI Code Associated With Solenoid Circuit 
Code present. 
FMI 3 diagnostic code, proceed to Test Step 2.

FMI 4 diagnostic code, proceed to Test Step 3.

FMI 5 diagnostic code, proceed to Test Step 4. 
Begin Process For FMI 3 Troubleshooting HERE 
2. Check The Machine Harness For A Short

A. Turn the key start switch and the disconnect switch OFF.

B. Disconnect the harness connection at solenoid.

C. Disconnect the harness connection at the ECM.

D. Measure the resistance of solenoid signal contact to all other ECM connections. 

Each reading is greater than 5K ohms. 
OK - All resistance readings 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.

Proceed to Test Step 7.  
Begin Process For FMI 4 Troubleshooting HERE 
3. Check The Machine Harness For An Open

A. Turn the key start switch and the disconnect switch OFF.

B. Disconnect the solenoid from the machine harness.

C. Disconnect the harness connection at the ECM.

D. Connect a jumper wire at the two contacts at the solenoid end of the wiring harness.

E. At the ECM side of the machine harness, measure the resistance from the signal to the return contact. 

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 solenoid signal or the return wire for the solenoid. 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.

Proceed to Test Step 7. 
Begin Process For FMI 5 Troubleshooting HERE 
4. Check The Solenoids

A. Turn the key start switch and the disconnect switch OFF.

B. Disconnect the solenoid from the machine harness.

C. At each solenoid, measure the resistance of the solenoid coil between signal contact and the return contact. 

Each resistance measurement is less than 50 ohms. 
OK - Each resistance measurement is less than 50 ohms.

Proceed to Test Step 5.

NOT OK - The resistance measurement for one or more of the solenoids is greater than 50 ohms. There is an open in one or more of the solenoids.

Repair: Replace the faulty solenoid or solenoids.

Proceed to Test Step 7.  
5. Check The Energize Circuits Of The Solenoid

A. Turn the key start switch and the disconnect switch OFF.

B. At the machine harness connectors for all of the solenoids, connect a jumper wire between signal contact of one of the solenoids and signal contact of a second solenoid.

C. Disconnect the machine harness connector J1 and J2 from the ECM.

D. Measure the resistance of the two solenoids connected by the jumper wire.

E. Use the process above to test another pair of solenoids until all the pairings have been tested.  

The resistance measurement is less than 5 ohms between the two energize circuits of the solenoids. 
OK -The resistance measurement is less than 5 ohms between the two energize circuits of the solenoid.

Proceed to Test Step 6.

NOT OK - The resistance measurement for the energize circuits of the solenoid is greater than 5 Ω. There is a problem in one or both of the solenoid energize circuits.

Repair: Repair the machine harness or replace the machine harness.

Proceed to Test Step 7.  
6. Check The Return Circuit For The Solenoid

A. Turn the key start switch and the disconnect switch OFF.

B. At the machine harness connector for one of solenoids , place a jumper wire between signal contact and return contact .

C. At the machine harness connector J1 or J2 for the ECM, measure the resistance between the energize circuit for the solenoid and the return contact.

D. Repeat the process above for the other solenoids  

All of the resistance measurements are less than 5 ohms. 
OK -All of the resistance measurements are less than 5 ohms.

Proceed to Test Step 7.

NOT OK - One or more of the resistance measurements is greater than 5 ohms.

Repair: Repair the machine harness or replace the machine harness.

Proceed to Test Step 7. 
7. Check If The Diagnostic Code Remains

A. Inspect the harness connectors and clean the contacts of the harness connectors.

B. Reconnect all harness connectors.

C. Turn key switch and disconnect switch ON.

D. Operate the machine.

E. Check if diagnostic code is active. 

Diagnostic code 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 may require replacement.

Prior to replacing this component, always contact the Technical Communication at your dealership for possible consultation with Caterpillar. This consultation may greatly effect repair time.

Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced.

STOP 

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