374F and 390F Excavators and 390F MHPU Mobile Hydraulic Power Unit Solenoid Valve (Switch Controlled) - Test Caterpillar


Solenoid Valve (Switch Controlled) - Test
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1.1. Machine ECM
2.1. Diagnostic Trouble Code Procedure

Machine ECM

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

Table 1
Machine ECM (MID 299) 
DTC  Code Description  System Response 
1160-3  Hydraulic Lock Solenoid: Voltage Above Normal   Hydraulic lock solenoid will not function. 
1160-6  Hydraulic Lock Solenoid: Current Above Normal   Hydraulic lock solenoid will not function. 

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 solenoid has failed.

  • The harness is shorted.

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

Possible causes for an FMI 6 Diagnostic code are:

  • The solenoid has failed.

  • The relay has failed.

  • The energize circuit of the relay is shorted to ground.

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


Illustration 1g03329907
Connections of the Hydraulic Lock Solenoid

Note: The diagram above is a simplified schematic of the hydraulic lock solenoid connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR2487 (374F) or Electrical Schematic, UENR2489 (390F) for the complete schematic.

Note: The following test procedure may create other diagnostic trouble codes. Ignore these created diagnostic trouble codes and clear the diagnostic trouble codes when the original diagnostic trouble code has been corrected.

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 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 this diagnostic code is active before performing a troubleshooting procedure.

Table 2
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 6 diagnostic code, proceed to Test Step 5. 
Begin Process For FMI 3 Troubleshooting HERE 
2. Check The Energize Circuit Of The Solenoid For A Short To +Battery Circuit

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

B. Disconnect the machine harness connectors from the solenoid and the ECM.

C. At the ECM harness connector, measure the resistance between the solenoid contact (A588-GN(Green)) and all contacts used in the ECM connectors. 

Each resistance measurement is greater than 5K Ω.  
OK - Each resistance measurement is greater than 5K Ω.

Repair: The solenoid has failed. Replace the solenoid.

Proceed to Test Step 5.

NOT OK - Each resistance measurement is not greater than 5K Ω. There is a short in the machine harness. The short is between the switch contact and the circuit that has a low resistance measurement.

Repair: Repair or replace the machine harness.

Proceed to Test Step 5. 
Begin Process For FMI 6 Troubleshooting HERE 
3. Check the Relay

A. Remove the jumper wire installed in the previous step and reconnect the solenoid.

B. Turn the key start switch and the disconnect switch to the ON position. Do not start the engine.

C. Observe the status of the diagnostic code.

D. Disconnect the proper relay from the fuse panel. 

The diagnostic code is no longer active when the relay is disconnected. 
OK - The diagnostic code is no longer active when the relay is disconnected. The circuit is correct. The relay has failed.

Repair: Repeat the test "Check The Relay" in order to verify the relay failure. Replace the relay.

Proceed to Test Step 5.

NOT OK - The diagnostic code remains active.

Proceed to Test Step 4. 
4. Check The Energize Circuit Of The Relay For A Short To Ground

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

B. The relay remains disconnected from the machine harness.

C. Disconnect the harness connectors from the ECM.

D. At the ECM harness connectors, measure the resistance between the relay signal contact to all contacts used in the ECM harness connectors. 

Each resistance measurement is greater than 5K Ω. 
OK - Each resistance measurement is greater than 5K Ω.

Proceed to Test Step 5.

NOT OK - Each resistance measurement is not greater than 5K Ω. There is a short in the machine harness. The short is between the relay signal contact and the circuit with the low resistance measurement.

Repair: Repair or replace the machine harness.

Proceed to Test Step 5. 
5.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 start switch and disconnect switch ON.

D. Operate the machine.

Check the status of the diagnostic code. 

The diagnostic code is not active. 
OK - The diagnostic code is no longer active. The problem may be intermittent. Resume normal machine operation.

STOP.

NOT OK - The diagnostic code is active. The ECM may have failed.

Repair: A failure of the ECM is unlikely. If the cause of the diagnostic code is not found, replace the ECM.

Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with AVSpare. This consultation may effect repair time.

If the ECM must be replaced, refer to Troubleshooting, "ECM - Replace".

STOP. 

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