Case IH 3403 – Engine Controller: Engine Controller Starter Relay Circuit Low Side Driver - Power Stage Overtemperature

The internal driver (power stage) inside the engine controller responsible for activating the starter relay has exceeded its maximum safe operating temperature. This is typically caused by excessive current draw on the starter relay circuit, a short circuit in the wiring, a failing relay coil, or an internal hardware failure within the controller itself.

• skid steer
• Steiger T4B
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• TR270
• SR series
• Farmall
• JX series (JX60-JX95)
• Maxxum
• T5 series
• 580N
• 580SN
• 590SN
• 570NXT

1. 1

   Wait and observe: Allow the module to cool down, cycle the ignition key, and see if the code clears on its own

2. 2

   Inspect the starter relay circuit wiring harness between the Engine Controller and the starter relay for shorts to ground or shorts to power

3. 3

   Test the starter relay (often designated as the K3 relay) for internal shorts or incorrect coil resistance

1. 1

   Disconnect Power

   Disconnect the negative battery cable before servicing the ECU or starter circuits to prevent further electrical damage.

2. 2

   Inspect and Replace Relay

   Locate the starter relay in the main fuse/relay panel. Test the relay coil resistance. If it is out of specification or shorted, replace the relay.

3. 3

   Check Wiring

   Perform a continuity and short-to-ground test on the wire running from the ECU starter relay output pin to the relay block. Repair any chafed, melted, or exposed wiring.

4. 4

   Replace the EDC

   If the external circuit (relay and wiring) is in perfect condition and the fault code persists after a cooldown period, the internal power stage is permanently damaged. Replace the EDC.

5. 5

   Reprogramming

   If the Engine Controller is replaced, the new module must be flashed with the correct software and the specific fuel injector codes must be written to the new controller using the Case IH Electronic Service Tool (EST).