Case IH 2650 – ZF Transmission Controller (ZTC): Range clutch K3 is shorted to ground

The electrical circuit controlling the K3 Range Clutch (3rd Gear) Solenoid Valve has a short circuit to ground (minus). This means voltage intended to actuate the K3 clutch solenoid is finding a premature path to the chassis ground, preventing the transmission from properly engaging 3rd gear.

• Steiger T4B
• 836D
• 845B
• 856C
• 621C
• 821F
• 921F
• Farmlift 632
• LM6.35

1. 1

   Inspect the transmission wiring harness between the ZTC module and the transmission control valve block for chafing, melting, or pinched wires that could cause a short to the chassis.

2. 2

   Disconnect the K3 clutch solenoid and the ZTC module. Use a multimeter to check the K3 signal wire for continuity to ground. If continuity exists, the harness is shorted.

3. 3

   Test the K3 clutch solenoid valve itself for an internal short to ground if the wiring harness tests good.

1. 1

   Isolate the Short

   Based on the diagnostic checks, determine if the short is in the OEM wiring harness or internal to the solenoid.

2. 2

   Repair Wiring

   If the harness is rubbed through and touching the frame, repair the damaged section of the wire and secure it with loom to prevent future chafing.

3. 3

   Replace Solenoid

   If the K3 solenoid is internally shorted, relieve hydraulic system pressure. Locate the transmission control valve block.

4. 4

   Remove connector

   Remove the electrical connector from the K3 solenoid.

5. 5

   Remove solenoid

   Unthread and remove the faulty K3 clutch solenoid valve.

6. 6

   Install solenoid

   Install the new solenoid valve and torque to OEM specifications.

7. 7

   Reconnect and clear codes

   Reconnect the wiring harness and clear the fault codes from the ZTC module.

8. 8

   Calibrate transmission

   Perform a transmission clutch calibration procedure to ensure the ZTC learns the fill times for the new K3 solenoid.