New Holland ENG 3131 – ENGINE: Grid Heater Always Switched On

The intake grid heater is continuously receiving power or its circuit is stuck in the closed/active position when it should be off.

• T5
• T6
• T6.125
• T6.180
• T7 Series
• T7.165S
• T7.175
• T7.190
• T7.210
• T7.225
• T8 Series
• Backhoe loaders (B90B - B115B Tier 3)
• skid steers
• wheel loaders

1. 1

   Check the grid heater relay for internal contacts that have welded shut by testing for continuity across its high-current terminals while the machine is completely powered off.

2. 2

   Inspect the grid heater relay wiring harness for a short circuit to the battery, looking for melted insulation, chafed wires, or exposed copper touching a constant 12V source.

3. 3

   Load-test the batteries and check for a parasitic draw, as a continuously running grid heater will rapidly drain the batteries.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shock, fire, or accidental grounding, as the grid heater circuit carries very high amperage.

2. 2

   Locate the Relay

   Locate the grid heater relay. Depending on the model, it may be mounted near the engine rear frame, the intake manifold, or on a dedicated electrical bracket.

3. 3

   Disconnect the Harness

   Detach the grid heater relay electrical connections/wiring harness.

4. 4

   Remove and Replace

   Unbolt the faulty grid heater relay and install the replacement unit. If the wiring harness is melted or damaged due to the constant heat/current, remove the damaged harness and install a new one.

5. 5

   Reassemble

   Reconnect the electrical connections to the new relay. (Note: On some models like the T7.210, accessing the grid heater components may require removing the left-hand air intake pipe).

6. 6

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic tool to clear the ENG 3131 fault code. Start the engine and verify the grid heater cycles off properly.