Case IH P4A – Digital Instrument Cluster (EIC) or Engine Controller (EDC): Coolant Temperature Sensor, Grounded Or Current Above Normal Range

The control module is receiving a voltage or current signal from the sensor circuit that exceeds the maximum expected threshold, or it has detected a direct short to ground in the sensor's wiring. This prevents the system from accurately reading the engine's coolant temperature.

• MXM
• MXM120
• MXM130
• MXM135
• MXM140
• MXM150
• MXM155
• MXM165
• MXM175
• MXM190
• TM120
• TM130
• TM140
• TM155
• TM175
• TM190

1. 1

   Inspect the wiring harness leading to the coolant temperature sensor for chafing, melted insulation, or exposed wires that could be shorting to the engine block (ground).

2. 2

   Disconnect the sensor and check the electrical connector for corrosion, moisture, or damaged pins.

3. 3

   Use a multimeter to check the resistance of the sensor itself. If there is no resistance (a dead short) whether the engine is hot or cold, the sensor has failed internally.

4. 4

   With the sensor disconnected, check the signal wire for a short to ground back to the ECU.

1. 1

   Cool Down

   Ensure the tractor is turned off and the engine is completely cool to prevent severe burns from hot, pressurized coolant.

2. 2

   Drain Coolant

   Drain a small amount of coolant from the radiator petcock to bring the fluid level below the sensor port. This prevents coolant from spilling everywhere when the sensor is removed.

3. 3

   Disconnect

   Unplug the electrical wiring harness connector from the coolant temperature sensor.

4. 4

   Remove Sensor

   Using a deep socket or wrench, carefully unscrew the faulty sensor from the engine block/thermostat housing.

5. 5

   Install New Sensor

   Thread the new sensor into the port by hand to prevent cross-threading, then tighten it to the manufacturer's specified torque.

6. 6

   Reconnect

   Plug the electrical connector back into the new sensor.

7. 7

   Refill and Test

   Refill the drained coolant back to the proper level. Start the engine, check the sensor area for leaks, and verify that the dashboard temperature gauge is reading correctly and the T4A fault code has cleared.