Case IH 3008 – Engine Control Unit (ECU A-9000): Engine Coolant Temperature Sensor Voltage Lower Than Expected

The Engine Control Unit (ECU) is sensing an analog input signal of less than 0.188 V in the signal circuit of the coolant temperature sensor, indicating a short circuit to ground in the sensor wiring or an internally shorted sensor.

• Farmall
• skid steer
• Steiger T4B
• 240 Series Axial-Flow Combines
• Magnum Series (235, 260, 290, 315, 340, 370)
• Steiger Series
• Optum Series
• Farmall Series (35A, 35C, 40C, 50C, 115U)
• Boomer Series (Tier 4B)

1. 1

   Inspect the wiring harness between the Coolant Temperature Sensor (B-9003) and the Engine ECU (A-9000) for chafing, melting, or pinched wires that could cause a short to the chassis/ground.

2. 2

   Disconnect the vehicle harness from the ECU A-9000 (often at connector X-9001) and disconnect the plug at the B-9003 sensor. Use a multimeter to check for continuity between the sensor signal wire and chassis ground. If continuity exists, the wiring harness is shorted.

3. 3

   If the wiring harness tests good, measure the resistance across the pins of the B-9003 coolant temperature sensor itself. If the resistance is near zero (dead short), the sensor has failed internally.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical spikes during repair.

2. 2

   Locate the Sensor

   Locate the Coolant Temperature Sensor (B-9003) on the engine block or cylinder head water jacket.

3. 3

   Harness Repair

   If your diagnostic checks revealed a short to ground in the wiring, trace the harness back to the A-9000 ECU, locate the damaged section, splice in new wire using weather-sealed connectors, and wrap it in protective loom.

4. 4

   Sensor Replacement

   If the sensor is internally shorted, place a catch pan under the engine, unplug the 2-pin electrical connector, unscrew the faulty sensor, thread the new OEM sensor into the port and tighten to specification, then reconnect the connector.

5. 5

   Refill and Test

   Top off the engine coolant to replace any lost fluid, reconnect the battery, start the engine, use a diagnostic scan tool to clear DTC 2213 (3008), and monitor live data to ensure the ECU is reading a normal coolant temperature voltage.