Case IH 3041 – Engine Control Module (ECM): HS Power stage cold start heater relay - SOURCE LOW

Indicates a 'SOURCE LOW' or a 'short to ground' on the High-Side (HS) power stage of the cold start heater relay. The system has detected that the voltage in the grid heater / cold start relay circuit has dropped below the expected threshold, meaning the electrical current is finding an unintended path to ground (a short circuit).

• Steiger
• Puma
• Magnum
• T6000 series

1. 1

   Verify overall battery voltage, as battery voltage signal issues can impact relay performance

2. 2

   Visually inspect the wiring harness connecting the ECM to the cold start heater relay for chafing, melted insulation, or bare wires touching the chassis

3. 3

   Inspect the connectors at the relay and the ECM for corrosion, moisture, or loose pins

4. 4

   Use a multimeter to test the cold start heater relay for an internal short to ground

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical shock or further shorting of the ECM.

2. 2

   Locate the Relay

   Locate the cold start heater relay (often mounted near the engine intake manifold or main electrical distribution box).

3. 3

   Isolate the Circuit

   Disconnect the wiring harness from the relay.

4. 4

   Test for Shorts

   Perform a continuity test on the wiring harness back to the ECM to isolate the short to ground.

5. 5

   Repair Wiring

   If the wiring is damaged or chafed against the engine block, repair or replace the affected section of the harness.

6. 6

   Replace Relay

   If the wiring tests fine, the short is likely internal to the relay itself. Remove the mounting bolts and replace the cold start heater relay.

7. 7

   Reassemble and Clear Codes

   Reconnect the harness and the battery. Turn the key on, clear the fault codes using a diagnostic tool, and cycle the key to verify the cold start heater engages properly without triggering the 3041 code.