D9T Track-Type Tractor Hydraulic System – MID 113 – CID 2596 – FMI 06

Conditions Which Generate This Code:

Illustration 1 g02155456

Brake pressure modulation solenoid connections

The CID 2596 diagnostic code is associated with the brake pressure modulation solenoid. The solenoid is connected to a PWM driver output of the Machine ECM. The FMI 06 means that the Power Train ECM has detected the electrical current in the solenoid circuit is above normal.

Conditions that may cause this diagnostic code to be activated are:

  • The energize circuit of the solenoid is shorted to a ground source.

  • The solenoid has failed.

  • The ECM has failed. This condition is unlikely.

Note: Poor connections may 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 the CID 2596 06 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 these diagnostic codes when the original diagnostic code has been corrected.


  1. Turn the disconnect switch and the key start switch to the ON position. DO NOT START THE ENGINE.
  1. While observing the status of the active CID 2596 06 diagnostic code, disconnect the Brake Pressure Modulation Solenoid from the machine harness.

Expected Result:

The active CID 2596 06 diagnostic code changes to a CID 2596 05 diagnostic code when the solenoid is disconnected.


  • YES – The active CID 2596 06 diagnostic code changes to a CID 2596 05 diagnostic code when the solenoid is disconnected. The solenoid circuit in the machine harness is correct. The solenoid has failed.

    Repair: Repeat this test “CHECK THE SOLENOID” to verify the solenoid failure. Replace the Brake Pressure Modulation Solenoid.After the solenoid is replaced, verify that the new solenoid has corrected the problem before operating the machine.


  • NO – The CID 2596 06 diagnostic code remains active. Disconnecting the solenoid did not change the status of the active diagnostic code. The solenoid is not causing the problem. Proceed to Test Step 2.


The solenoid remains disconnected from the machine harness.

  1. Turn the key start switch and the disconnect switch to the OFF position.
  1. Disconnect the machine harness ECM connectors J1 and J2 from the Power Train ECM.
  1. At the machine harness ECM connectors, measure the resistance from the energize contact J1-58 (wire F792-WH) to frame ground. Measure the resistance from the signal contact J1-58 (wire F792-WH) to all of the other contacts that are used in J1 and J2 Power Train ECM connectors.
  1. While observing the multimeter resistance measurements, wiggle the machine harness connectors for the ECM and the solenoid. Gently pull on the wires and move the wires around.

Expected Result:

Each resistance measurement is greater than 5000 ohms at all times during the manipulation of the harness and connectors.


  • OK – Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.

  • NOT OK – One or more of the resistance measurements is less than 5000 ohms. The resistance measurement is indicating that a short is present in the machine harness. The short is between wire F792-WH and either frame ground or the circuit with the low resistance measurement.

    Repair: Check all of the connectors that are in the circuit. Ensure that all of the contacts for the circuit are in good condition, are clean, and are securely fastened in each of the harness connectors.For information on testing for short circuits and finding short circuits, refer to the Troubleshooting, “Wiring Harness (Short Circuit) – Test”. Repair the machine harness or replace machine harness.



  1. Inspect the harness connectors and clean the contacts of the harness connectors that are involved in the circuit. Check the wires for damage to the insulation that can be caused by excessive heat, corrosion, or chafing.
  1. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
  1. Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are fastened.
  1. Turn the disconnect switch and the key start switch to the ON position. DO NOT START THE ENGINE.
  1. Check the status of the CID 2596 06 diagnostic code.

Expected Result:

The CID 2596 06 diagnostic code is not active.


  • OK – The CID 2596 06 is not active. The diagnostic code does not exist at this time. The initial diagnostic code may have been caused by a poor electrical connection that was corrected when a harness connector was disconnected and reconnected.

    Repair: Resume normal machine operation.


  • NOT OK – The CID 2596 06 diagnostic code is still active. The diagnostic code has not been corrected. The Power Train ECM may have failed.

    Repair: Check the circuit again. With Caterpillar Electronic Technician (Cat ET), if available, perform a “Wiggle Test” on the machine wiring harness. The wiggle test may detect momentary or intermittent shorts or opens in the machine wiring harness.Verify that all possible causes of the diagnostic code have been investigated. If the cause of the diagnostic code is not found, replace the Power Train ECM. Prior to replacing a power train ECM, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the power train ECM requires replacement, refer to Troubleshooting, “Electronic Control Module (ECM) – Replace”.


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