Case IH 32 – Instrumentation Controller (ICU) / TMF: Ground Speed Signal is failed in the Instrumentation Controller

The Data Bus has signaled that the transmission speed sensor or radar gun has failed, or the signal is missing/invalid. Because the Instrumentation Controller (ICU) broadcasts this speed data to other modules, systems like the PTO, Hitch, and auto-steering may also fail or log communication codes when this signal drops.

• Magnum
• Case IH MX Magnum Series
• Case IH TG Series
• Case IH Steiger Series (350 to 600)
• Case IH Puma Series

1. 1

   Visually inspect connector ends for damaged, bent, pushed-back, or corroded pins before replacing parts.

2. 2

   If equipped with a Radar Gun (Radar fault cause): Disconnect connector C068 at the radar. Turn the tractor key to the 'RUN' position and check the power supply at pin C of connector C068; it should read approximately 5 VDC.

3. 3

   If equipped with a Radar Gun (Radar fault cause): Check for good continuity from pin A of connector C068 to a clean chassis ground.

4. 4

   If equipped with a Radar Gun (Radar fault cause): Test the radar function. The signal outputs from Pin B of the radar and connects to pin 13 (or 19) of the instrument cluster through Pin 25 of connector C060. Using an oscilloscope, wave your hand quickly in front of the radar to test for a frequency change in the signal.

5. 5

   If equipped with a Transmission Wheel Speed Sensor (Sensor fault cause): Locate the sensor and check its wiring (Cavity A is the Signal, Cavity B is Ground).

6. 6

   If equipped with a Transmission Wheel Speed Sensor (Sensor fault cause): Test the sensor's internal resistance; a healthy sensor typically reads around 2700 ohms. Check for open circuits or wiring shorts to ground.

7. 7

   If the sensor and wiring are perfectly intact, check for a software execution error or hardware failure within the Instrumentation Controller itself.

1. 1

   Power down tractor

   Power down the tractor, remove the key, and disconnect the battery ground cable to prevent electrical shorts.

2. 2

   Locate faulty component

   Locate the faulty component (either the transmission wheel speed sensor on the transmission housing or the radar gun mounted under the cab/chassis).

3. 3

   Disconnect wiring harness

   Carefully disconnect the wiring harness connector from the sensor (e.g., connector C068 for the radar).

4. 4

   Remove faulty sensor

   Unbolt and remove the faulty speed sensor or radar unit from the vehicle.

5. 5

   Clean mounting surface

   Clean the mounting surface to ensure a flush fit.

6. 6

   Install new sensor

   Install the new speed sensor or radar gun and tighten the mounting hardware to OEM specifications.

7. 7

   Reconnect wiring harness

   Reconnect the wiring harness, ensuring the connector clicks securely into place.

8. 8

   Reconnect battery

   Reconnect the battery ground cable.

9. 9

   Test tractor

   Turn the key to the "RUN" position and test the tractor by driving it forward to verify that the speedometer registers and the ground speed signal is restored to the guidance/PTO systems.