New Holland ENG 3143 – Engine ECU: Grid Heater Switch Off Test (Voltage Drop Too High)

The engine controller runs a diagnostic test on the cold start system (grid heater) during operation. When the grid heater is commanded to turn off, the system measures the voltage drop across the circuit. A "Voltage Drop Too High" indicates excessive electrical resistance, a short, or a faulty connection in the grid heater circuit, relay, or wiring harness.

• T8.xxx Series
• T7.230
• CR9090
• CX8080 Elevation
• CX8090 Elevation
• B90B
• B100B
• B110B
• B115B
• L180
• L230
• LT185.B
• 435
• 440

1. 1

   Check battery voltage to ensure the batteries are strong enough to support the load. Clean the battery posts and chassis grounds, as poor grounds are a primary cause of high voltage drops.

2. 2

   Locate the electrical board/fuse box and check the dedicated Grid Heater Fuse (often a 10A fuse depending on the model).

3. 3

   Inspect the grid heater power relay/solenoid for heavy corrosion across the terminals. Corroded relay contacts will cause a high voltage drop.

4. 4

   Inspect the heavy-gauge cables going to and from the relay and the intake manifold grid heater element for chafing, melting, or loose retaining nuts.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent accidental shorts, as the grid heater circuit carries high amperage.

2. 2

   Clean Connections

   Remove the wiring from the grid heater power relay and the grid heater element on the air intake. Clean all ring terminals and mounting studs with a wire brush to remove corrosion.

3. 3

   Test/Replace the Relay

   If cleaning the connections does not resolve the excessive voltage drop, the internal contacts of the relay are likely burnt or pitted. Replace the grid heater power relay.

4. 4

   Inspect the Heater Element

   If the relay is functioning properly, inspect the grid heater element inside the intake manifold. If the element is internally shorted or damaged, replace the grid heater unit.

5. 5

   Reassemble and Clear Codes

   Reconnect all wiring, ensuring the flange nuts are tightened to spec. Reconnect the battery, clear the ENG 3143 code from the Engine ECU, and cycle the key to verify the cold start test passes without logging the code.