Case IH F50 – Transmission Controller (TCU) / Processor: Transmission Output Speed Sensor Short To Ground

The transmission controller is detecting a short to earth (ground) on the signal circuit from the transmission output speed sensor. Symptoms include inhibited upshifts in high range and a 1-2 second delay in allowing upshifts after a clutchless take-off.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum
• Puma

1. 1

   Turn off the machine and disconnect the transmission processor connectors C100 and C101.

2. 2

   Locate and disconnect the transmission output speed sensor connector C038.

3. 3

   Test the wiring harness for an open or short circuit to ground specifically on pin C101-6.

4. 4

   Test the sensor itself by checking for a short to earth (ground) on each sender terminal while installed in the transmission.

5. 5

   Measure the resistance of the sender (should read approximately 0.8 to 1.2 kOhms at 20°C).

1. 1

   Repair Wiring (If Applicable)

   If your multimeter indicates a short to ground on the harness side (pin C101-6), trace the wiring loom between connector C038 and C101. Locate the chafed or melted wire, repair the damaged section, and secure it away from pinch points.

2. 2

   Replace Sensor (If Applicable)

   If the sensor fails the resistance test (reads outside of 0.8-1.2KΩ) or shows an internal short to ground on its terminals, remove the faulty sensor from the transmission housing and install a new one.

3. 3

   Reassembly

   Reconnect the transmission output speed sensor connector (C038) and the processor connectors (C100 & C101).

4. 4

   Verification

   Clear the stored fault codes using the tractor's H-Menu or a diagnostic service tool. Test drive the tractor to verify that high-range upshifts are restored and the clutchless take-off delay is resolved.