Massey Ferguson 626.05 – Engine Control Unit (ECU): Engine Intake Heater Low Voltage / Grid heater relay current below normal or open circuit

The system has detected that the current draw from the intake grid heater relay is lower than expected. This typically indicates an open circuit, a disconnected wire, or a failed relay coil preventing the intake heater from operating.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724

1. 1

   Turn the ignition off for a minimum of 60 seconds to allow the ECU to power down completely before testing

2. 2

   Locate the intake grid heater relay (70 Amp, 4-pin) and check for continuity across the relay coil terminals using a multimeter (an open reading indicates a blown internal coil)

3. 3

   Inspect the wiring harness between the Engine ECU and the intake heater relay socket for broken wires, chafing, or disconnected plugs

4. 4

   Check the relay socket and the intake heater element connections for heavy corrosion or burnt pins

1. 1

   Turn off the tractor ignition and disconnect the negative battery cable to prevent accidental shorts.

2. 2

   Locate the grid heater relay in the electrical panel or engine bay harness.

3. 3

   Unplug the relay and inspect the socket terminals. Clean any dirt or corrosion using electrical contact cleaner.

4. 4

   If the relay failed the continuity test during diagnostics, replace it with a new OEM 70A relay.

5. 5

   If the relay is functional, trace the wiring from the relay socket back to the ECU and out to the intake heater element. Repair any broken wires or replace damaged connectors.

6. 6

   Plug the new or tested relay back into the socket.

7. 7

   Reconnect the battery cable.

8. 8

   Turn the ignition on and verify that the 000626.05 / SPN 626 FMI 5 code has cleared from the dash display.