Case IH F49 – Transmission Controller / Processor: Transmission Output Speed Sensor Open Circuit

The controller is not detecting a complete electrical circuit to the transmission output speed sensor, which prevents the system from accurately reading the transmission's output RPM. When this code is active, upshifts in the high range are inhibited, and operators will typically experience a 1-2 second delay in allowing upshifts after a clutchless take-off.

• MXM
• MXM series
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• MX/TG series

1. 1

   Disconnect the transmission processor connectors (C100 & C101) and the transmission output speed sensor connector (C038). Test the wiring harness for an open or short circuit between the sensor connector and pin C101-6 on the processor.

2. 2

   With the sensor installed in the transmission, check for a short to earth (ground) on each of the sender's terminals.

3. 3

   Measure the internal resistance of the speed sensor. At 20°C (68°F), the resistance should be approximately 0.8 to 1.2 K-Ohms. If outside this specification, the sensor has failed internally.

4. 4

   Ensure the sensor is properly adjusted, as an improper gap can cause signal issues. Turn the sensor in until it bottoms out on the shaft, then back it out 1/8 of a turn and tighten the lock nut.

1. 1

   Power down the tractor and locate the transmission output speed sensor on the transmission housing.

2. 2

   Disconnect the C038 electrical connector from the sensor.

3. 3

   Perform the wiring continuity and sensor resistance diagnostic checks outlined above.

4. 4

   If the wiring harness is damaged (open circuit to C101-6), repair or replace the affected wiring.

5. 5

   If the wiring is intact but the sensor fails the resistance test (outside 0.8-1.2 K-Ohms) or is shorted to ground, remove the lock nut and unthread the faulty sensor from the transmission housing.

6. 6

   Thread the new OEM transmission output speed sensor into the housing until it gently bottoms out on the internal shaft.

7. 7

   Back the sensor out exactly 1/8 of a turn to set the proper air gap, then securely tighten the lock nut.

8. 8

   Reconnect the C038 electrical connector and the processor connectors.

9. 9

   Clear the fault codes using the tractor's H-Menu or a diagnostic service tool, and test drive the tractor to ensure high-range upshifts operate without delay.