Case IH 19215 – Engine Control Unit (ECU): Blow By 3-way valve short circuit to ground

The Engine Control Unit (ECU) hardware has detected an electrical failure—specifically a short circuit to ground—on the power stage output of the Blow By 3-way valve. If the blow-by valve is configured to open when not energized and a short circuit to ground is present, the ECU is forced to open the main relay to allow the blow-by valve to open.

• Tier 4b
• Farmall 95U
• Farmall 105U
• Farmall 115U Pro
• N-series TLBs

1. 1

   Ensure the power supply is switched OFF (ignition key in the OFF position) before disconnecting any electrical connectors

2. 2

   Inspect the wiring for broken, disconnected, or chafed sections that could be grounding out against the chassis

3. 3

   Check the wiring harness between the Engine ECU and the Blow By 3-way valve for a short circuit to ground or to an external power source

4. 4

   Test the Blow By 3-way valve itself to determine if the short circuit is internal to the valve's power stage

5. 5

   Verify proper battery voltage, as extreme voltage fluctuations can sometimes trigger power stage output errors

1. 1

   Turn the ignition key to the OFF position to safely isolate the ECU.

   Ensure the power supply is switched OFF before disconnecting any electrical connectors.

2. 2

   Locate the Blow By 3-way valve on the engine and disconnect its electrical connector.

3. 3

   Disconnect the corresponding connector at the Engine ECU.

4. 4

   Using a multimeter, perform a continuity test to ground on the signal and power wires.

5. 5

   If the wiring harness is shorted to ground, repair the damaged section of the wire or replace the harness.

6. 6

   If the wiring tests good, the short circuit is internal to the valve. Remove the defective Blow By 3-way valve and install a replacement.

7. 7

   Reconnect all ECU and valve connectors.

8. 8

   Turn the ignition ON and clear the fault codes from the ECU.