259D Skid Steer Loaders Machine Systems – MID 039 – CID 1936 – FMI 06

Conditions Which Generate This Code:

Illustration 1g03371909

Schematic of the High Flow Relay

This diagnostic code is associated with the Hydraulic System High Pressure Solenoid. This diagnostic code is recorded when the ECM detects a short to ground in the electrical path from the ECM to the solenoid. The return circuit is connected for all solenoids. The return circuit connects to contacts J2-4 (wire H807-YL) of the Machine ECM.

The possible causes of this diagnostic code are listed:

  • The solenoid winding has low impedance or the solenoid winding is shorted.

  • The signal circuit from the ECM for the solenoid is shorted to ground.

System Response:

The machine response is listed:

  • The boost flow is disabled until the fault is cleared and aux input returns to neutral

Note: The following test procedure may create other diagnostic codes. Ignore the created diagnostic codes. Clear these diagnostic codes when the original diagnostic code is corrected.

Note: Ensure that the diagnostic code is active and that the diagnostic code indicator is active.


  1. Turn the key start switch to the ON position.

  1. Observe the ON/OFF status of the diagnostic code indicator.

  1. Disconnect the solenoid with the diagnostic code from the harness.

Expected Result:

The diagnostic code indicator remains active.


  • YES - The diagnostic code indicator remains active. This indicates that a diagnostic code remains active. The harness has failed or the ECM has failed. Proceed to Test Step 2.

  • NO - The diagnostic code indicator is inactive.

    Repair: The solenoid valve has failed or the connecting harness has failed. Repeat this test in order to verify the failure. Repair the solenoid or replace the solenoid. Repair the connecting harness or replace the connecting harness at the solenoid.



  1. Turn the key start switch to the OFF position.

  1. The solenoid valve of the previous test step remains disconnected.

  1. Disconnect the harness from the Machine ECM.

  1. At the harness connector for the ECM, measure the resistance between the contact J2-4 for the solenoid (wire G970-BU) and contact J1-23 (wire 203-BK).

Expected Result:

The resistance is less than 5000 Ohms.


  • YES - Resistance is less than 5000 Ohms (continuity).

    Repair: The machine harness has failed. The corresponding solenoid wire is shorted to ground in the harness. Repair the harness or replace the harness.


  • NO - Resistance is greater than 5000 Ohms (no continuity).

    Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace"


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