Case IH 3267 – Engine Controller: Main relay 3 _Short circuit to Battery

The control module has detected that the voltage on the circuit controlling Main Relay 3 is unexpectedly high, indicating that the circuit is shorted directly to battery voltage (B+).

• Magnum 235 - 340 (Series 4)
• Puma series
• MX / TG series
• Steiger series

1. 1

   Locate Main Relay 3 in the main relay panel (usually located in the cab or the main chassis electrical distribution box)

2. 2

   Check the reference supply lines running from the Engine Controller to Main Relay 3 for a short circuit to battery voltage

3. 3

   Inspect the wiring harness between the ECU and the relay block for chafed wires, melted insulation, or pinched harnesses that could bridge the relay control wire to a constant 12V source

4. 4

   Remove Main Relay 3 and test the internal coil for a dead short using a multimeter

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical damage during testing.

2. 2

   Remove the Relay

   Pull Main Relay 3 from the relay panel.

3. 3

   Isolate the Short

   With the relay removed and the battery temporarily reconnected for testing, use a multimeter to probe the relay socket's control circuit pin. If it reads 12V when it shouldn't be energized, the short is in the wiring harness.

4. 4

   Repair Wiring

   Trace the wire back to the Engine ECU. Repair or replace the section of the wiring harness where the short to battery voltage is occurring.

5. 5

   Replace the Relay

   If the wiring tests good but the relay itself is internally shorted (or stuck closed), replace the relay with a new OEM unit.

6. 6

   Reassemble and Clear Codes

   Reinstall the relay, reconnect the battery, turn the ignition on, and use a diagnostic scan tool to clear fault code 3267. Start the engine to verify the code does not return.