New Holland ENG 422 – Engine Control Module (ECM): Engine Coolant Level Sensor (optional) is failed or the jumper plug is missing.

The ECM has detected erratic, intermittent, or incorrect data from the coolant level sensor circuit, such as voltage simultaneously on both the coolant level high and low signal pins, or no voltage on either pin. The engine loses its automatic protection/derate capabilities for low coolant levels.

• TG210
• TG230
• TG255
• TG285
• T8040
• T7.270
• CR9090
• CX8080
• CX8090
• TerraGator

1. 1

   Determine Equipment Configuration: Check the radiator top tank / surge tank to see if the machine is actually equipped with a physical coolant level sensor. If it is not, locate the coolant level sensor breakout on the engine wiring harness to see if the factory jumper plug is missing or damaged.

2. 2

   Visual Pin Inspection: Turn the keyswitch OFF. Disconnect the coolant level sensor or jumper plug. Inspect the harness connector for bent, broken, pushed-back, or expanded pins, as well as moisture or corrosion.

3. 3

   Check 5V Reference: Switch the key ON (engine not running). Using a multimeter, check for a 5-volt supply at the sensor harness connector coming from the ECM. If less than 5V is present, there is an open circuit or short to ground in the engine harness, or the ECM has failed. If 5V is present, the wiring to the ECM is good; the fault lies within the sensor itself or the jumper plug.

1. 1

   Turn keyswitch OFF

   Turn the keyswitch to the OFF position.

2. 2

   Disconnect harness

   Disconnect the wiring harness from the faulty coolant level sensor or remove the damaged jumper plug.

3. 3

   Clean connector

   Clean the engine harness connector thoroughly with electrical contact cleaner and allow it to dry to ensure no moisture is bridging the pins.

4. 4

   Replace sensor (if equipped)

   If equipped with a sensor: Unthread the faulty coolant level sensor from the expansion tank (be prepared to catch a small amount of coolant) and install the replacement sensor.

5. 5

   Install jumper plug (if not equipped)

   If NOT equipped with a sensor: Install a new OEM jumper plug into the engine harness connector to properly terminate the circuit.

6. 6

   Reconnect harness

   Reconnect the engine wiring harness securely.

7. 7

   Validate repair

   Turn the keyswitch ON, start the engine, and let it idle for at least 1 minute. The ECM will run a continuous diagnostic; once it passes, the amber warning light will turn off, and the fault code status will change from ACTIVE to INACTIVE.

8. 8

   Clear fault code

   Use a diagnostic tool (such as New Holland EST or Jaltest) to clear the inactive fault code from the ECM's memory.