Case IH 9022 – Engine Control Unit (ECU): 5Vdc Supply 2 defect

The 5-volt reference circuit #2, which supplies power to various engine sensors, is operating outside of its allowable voltage range (HIGH > 5.2 V or LOW < 4.6 V).

• STX Steiger
• Puma series (165, 180, 195, 210, 225 CVX)
• Steiger series
• MX/TG series

1. 1

   Check for a steady 5.0 VDC at the sensors powered by the Supply 2 circuit

2. 2

   Inspect the wiring harness going to the 5V sensors for visible damage, chafing, or exposed wires that could cause a short to ground (LOW) or a short to battery (HIGH)

3. 3

   Disconnect sensors on the 5V Supply 2 circuit one by one to see if the voltage returns to the normal 4.6V–5.2V range to isolate a shorted sensor

1. 1

   Locate components

   Turn off the machine and locate the Engine ECU and the sensors on the 5V Supply 2 circuit.

2. 2

   Inspect ECU pins

   Disconnect the main harness from the ECU and check the pins for corrosion or damage.

3. 3

   Replace shorted sensor

   If a specific sensor was identified as shorted during the diagnostic checks, replace that sensor.

4. 4

   Repair or replace wiring harness

   If the wiring harness is damaged, repair the exposed/broken wires or replace the affected harness section.

5. 5

   Replace Engine ECU

   If the wiring and sensors are intact but the ECU is still outputting incorrect voltage (>5.2V or <4.6V) directly at the pin, the Engine ECU itself may have an internal hardware failure and will require replacement.

6. 6

   Verify repair

   Clear the fault codes and cycle the key to verify the repair.