Case IH 736-16 - DEC – Transmission Control Unit (TCU) or Vehicle Control Unit (VCU): Transmission C3 clutch solenoid electrical circuit fault voltage high

The control module has detected that the voltage on the C3 clutch solenoid circuit is above the normal operating range. This condition is typically caused by the solenoid's energize circuit shorting to a positive battery circuit (+VDC), an open circuit defaulting to a high reference voltage, or an internal failure of the solenoid coil itself.

• MAGNUM AFS Connect
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• Magnum 370
• Maxxum 5120
• Maxxum 5130
• Maxxum 5140
• Maxxum 5150
• Maxxum MX100
• Maxxum MX110
• Maxxum MX120
• Maxxum MX135
• Maxxum MX150
• Maxxum MX170
• 9380 Quadtrac
• STX Steiger

1. 1

   Key Off & Disconnect: Turn the key start switch and the main battery disconnect switch to the OFF position. Disconnect the machine harness connectors from the C3 clutch solenoid and the Transmission ECU.

2. 2

   Inspect Connectors: Inspect the harness connectors for corrosion, debris, or bent pins. Check the wiring for damage to the insulation caused by excessive heat, battery acid, or chafing.

3. 3

   Check for Short to Battery: With the ECU and solenoid disconnected, turn the key switch ON. Measure the voltage on the solenoid's signal wire to ground. If battery voltage is present, the wiring harness is shorted to a power source and must be repaired.

4. 4

   Resistance Test: Measure the resistance across the pins of the C3 clutch solenoid itself. If the resistance is out of specification (indicating an internal short or open coil), the solenoid has failed and requires replacement.

5. 5

   Pull Test: Perform a gentle pull test (approx. 10 lbs) on the wires associated with the C3 circuit at the connector to ensure the pins are properly seated and crimped.

1. 1

   Power Down

   Ensure the tractor is parked on a level surface, the engine is off, and the battery disconnect switch is turned OFF.

2. 2

   Locate the Solenoid

   Locate the transmission powershift valve block on the side of the transmission housing. Identify the C3 clutch solenoid (refer to the valve block diagram; it is usually grouped with the C1, C2, C4, and C5 solenoids).

3. 3

   Harness Repair (If Applicable)

   If the diagnostic checks revealed a short to battery voltage in the harness, trace the wire back to the ECU, locate the chafed/melted section, and splice in a repair using weather-sealed connectors.

4. 4

   Remove the Solenoid

   If the solenoid itself failed, disconnect its electrical connector. Remove the retaining bolt or snap ring securing the C3 solenoid to the powershift valve block.

5. 5

   Extract and Clean

   Pull the solenoid straight out of the bore. Clean the bore in the valve block with a lint-free cloth, ensuring no debris enters the transmission hydraulic circuit.

6. 6

   Install New Solenoid

   Lubricate the O-rings on the new C3 clutch solenoid with clean transmission fluid. Carefully insert it into the valve block and secure it with the retaining hardware.

7. 7

   Reconnect and Test

   Reconnect the electrical connector, ensuring the locking tab clicks into place. Turn the battery disconnect ON, clear the fault codes via the cab display, and test drive the tractor through all powershift gears to verify the C3 clutch engages properly without triggering the 736-16 code.