Massey Ferguson 3512.03 – Engine Control Unit (ECU): Engine Module 12 Volt Sensor Supply Voltage Issue (ECU)

The Engine Control Unit has detected that the supply voltage on the sensor #4 circuit is above specification. The voltage is higher than normal, which typically indicates that the circuit is short-circuited to a high voltage source.

• 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

   Verify that the main battery supply to the ECU is correct and not unusually low or surging

2. 2

   Inspect the ECU wiring harness routing and connections for rubbed-through wires, damaged connectors, or pushed-out pins

3. 3

   Use a multimeter to measure the voltage on the Sensor Supply #4 circuit to confirm if it is reading out of range high

4. 4

   Check the connections to the sensor on the #4 supply circuit for an open circuit or a short to a higher voltage source

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent further electrical damage.

2. 2

   Inspect and Clean Connectors

   Disconnect the ECU harness and the specific sensor(s) on the #4 supply circuit. Clean the contacts and check for moisture or corrosion that could bridge circuits and cause a short to power.

3. 3

   Trace the Harness

   Trace the wiring harness for the Sensor Supply #4 circuit. Look for areas where the wire insulation may have chafed against the engine block or another power wire, causing a short to a 12V source.

4. 4

   Repair Wiring

   If a short is found in the harness, repair the damaged wire(s) using proper splicing techniques and heat shrink, or replace the affected harness section.

5. 5

   Test the Sensor

   If the wiring is intact, the sensor itself may have failed internally, shorting the supply voltage. Replace the sensor if it fails a bench test.

6. 6

   ECU Replacement/Reprogramming

   If the wiring harness and sensor are both in good working order, the ECU itself has likely suffered an internal failure on the 5V/12V supply circuit. The ECU will need to be reprogrammed or replaced by an authorized dealer.

7. 7

   Clear Codes

   Reconnect the battery, turn the key on, and use a diagnostic tool to clear the fault code and verify the repair.