Case IH 3048 – Engine Controller (ECM / EDC): Main Relay 2 Failure _Short circuit to Ground

Indicates that the voltage on the control circuit for this relay has dropped to zero or is grounding out inappropriately.

• Magnum 235–340 (Series 4)
• Puma series
• Puma 210
• Steiger series
• MX/TG series
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Axial-Flow 7240 Tier 4B
• 580 Super N backhoes

1. 1

   Inspect the wiring harness between the Engine Controller (ECM) and Main Relay 2 for a physical short to ground (look for chafed wires, melted insulation, or pinched harnesses)

2. 2

   Test Main Relay 2 (or High Pressure Pump Relay) for internal shorting

3. 3

   Check the alternator voltage governor device, as a defect here is explicitly linked to this code

4. 4

   Verify the Engine Controller (ECM) condition if the wiring, relay, and alternator are intact

1. 1

   Isolate the Circuit

   Disconnect Main Relay 2 and use a multimeter to check for continuity to ground on the ECM control wire.

2. 2

   Repair Wiring

   If a short is found in the harness, repair or replace the damaged section of the wiring.

3. 3

   Replace the Relay

   If the wiring is good but the relay is internally shorted, replace Main Relay 2.

4. 4

   Address the Alternator

   If the alternator voltage governor is found to be defective during diagnostics, replace the governor device or the entire alternator assembly.

5. 5

   Replace the ECM

   If all external circuits, relays, and the alternator test perfectly, the official service guide states to "Replace engine controller".