Case IH 491 – Engine ECU: Wastegate 2 voltage is too high

The Engine Control Unit (ECU) is receiving a voltage signal from the Wastegate 2 control circuit that exceeds the maximum expected threshold. This typically points to a short circuit to a high-voltage source (such as a 12V or 5V supply line), an open ground circuit, or an internal electrical failure within the wastegate solenoid/actuator itself.

• MX Magnum
• STX Steiger
• Magnum series tractors
• Steiger series tractors
• Puma series tractors
• Axial-Flow (AFX) combines
• Equipment running dual-wastegate or specific electronic wastegate turbocharger setups

1. 1

   Inspect the wiring harness routed between the Engine ECU and the Wastegate 2 solenoid for chafed, melted, or pinched wires

2. 2

   Disconnect the Wastegate 2 solenoid and check the connector pins for corrosion, moisture ingress, or pushed-out pins

3. 3

   Using a multimeter, check the signal wire at the solenoid connector for a short to battery voltage or a 5V reference line

4. 4

   Verify the integrity of the ground circuit for the solenoid

5. 5

   Measure the internal resistance of the Wastegate 2 solenoid and compare it to OEM specifications to determine if the coil has failed internally

1. 1

   Power Down

   Turn off the machine and engage the battery disconnect switch to prevent electrical spikes.

2. 2

   Access the Turbocharger

   Locate the Wastegate 2 solenoid/actuator on the engine's turbocharger assembly.

3. 3

   Harness Repair

   If the diagnostic checks revealed a short or broken wire, repair the wiring harness by splicing in new wire or replacing the damaged connector pigtail. Route the harness away from high-heat or high-vibration areas.

4. 4

   Component Replacement

   If the wiring is intact but the solenoid failed the resistance test: disconnect the electrical connector, remove the mounting hardware and disconnect the mechanical linkage attaching the actuator to the wastegate valve, install the new wastegate solenoid/actuator, and adjust the linkage to the correct preload specification as outlined in the specific engine's service manual.

5. 5

   Reassembly & Testing

   Reconnect the electrical harness. Turn on the battery power, clear the inactive fault codes using the CNH Electronic Service Tool (EST) or dashboard diagnostic menu, and run the engine under load to verify the code does not return.