Case IH 2558 (1044.15) - DEC – DEC: Hydro 1 solenoid – short circuit to 12V

The drivetrain/transmission system has detected that the electrical circuit controlling the Hydrostat 1 (Hydro 1) control solenoid is shorted to a high voltage source (12V).

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• Case IH Puma CVX Series
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1. 1

   Inspect the Hydrostat 1 solenoid connector (X-544), intermediate wire harness connectors, and UCM/DEC module connectors. Ensure they are securely connected, free of corrosion, and that pins are tight.

2. 2

   Test the Hydrostat 1 solenoid resistance by disconnecting it and measuring across the terminals with a multimeter (expected: 8 to 11 Ohms). Out of spec indicates a faulty solenoid.

3. 3

   Test the Hydrostat 1 Solenoid power and ground circuits (circuits 7407 and 7408) for a short to 12V with the solenoid and UCM disconnected. Voltage present indicates a chafed wiring harness.

1. 1

   Prepare machine for repair

   Turn off the tractor, engage the parking brake, and disconnect the battery to prevent accidental shorts during repair.

2. 2

   Locate the solenoid

   Locate the Hydro 1 solenoid. Depending on your specific model, it is located either in the bell housing or inside the transmission side cover.

3. 3

   Disconnect electrical connector

   Disconnect the 2-pin electrical connector from the solenoid.

4. 4

   Repair wiring (if applicable)

   If the fault is wiring-related: Trace the harness back toward the UCM, locate the chafed section shorting to 12V, and repair the wiring. Replace the connector housing if the pins are damaged.

5. 5

   Remove faulty solenoid (if applicable)

   If the fault is the solenoid: Remove the retaining hardware securing the Hydro 1 solenoid to the valve body/transmission housing and extract the faulty solenoid.

6. 6

   Install new solenoid

   Lubricate the O-rings on the new transmission hydrostat control solenoid with clean transmission fluid and install it into the housing. Secure it with the retaining hardware.

7. 7

   Reconnect electrical connector

   Reconnect the electrical connector.

8. 8

   Clear fault code

   Reconnect the battery, turn the key on, and use your diagnostic tool to clear the error code from the UCM/DEC.

9. 9

   Verify repair

   Test the transmission system for normal operation to verify the fix.