Deutz-Fahr 223 – EMR3: Start Relay (High Side) Short Circuit

The engine's electronic control module (EMR3) has detected an electrical anomaly in the starting circuit where the current draw is above the expected range on the high side of the start relay's power stage. This indicates a short circuit to the battery's positive terminal (+Ubatt).

• 3 Series
• 4 Series
• 5 Series
• 6 Series
• 7 Series
• 8 Series
• 9 Series

1. 1

   Verify battery health, ensuring it is fully charged (approximately 12.6 volts) and terminals are clean and secure

2. 2

   Inspect fuses related to the starting and ignition system for any blown fuses indicating a short circuit

3. 3

   Visually inspect the wiring harness between the ECU, start relay, and starter motor for chafing, melting, or corrosion

4. 4

   Perform a relay swap test by swapping the start relay with an identical non-critical relay (like the horn relay) to see if the engine starts

5. 5

   Test the relay with a multimeter for continuity, checking for an open circuit in the coil and verifying the switch closes when energized

1. 1

   Disconnect battery

   Before beginning any electrical repairs, disconnect the battery to prevent short circuits and ensure safety.

2. 2

   Repair or replace wiring

   If diagnostic checks reveal damaged wiring or corroded connectors, repair or replace them, ensuring all connections are clean and secure.

3. 3

   Replace start relay

   If the start relay is faulty, replace it with a genuine OEM part. It is typically located in the main fuse box or engine wiring harness.

4. 4

   Reset ECU

   Switch the ignition off, wait for the ECU to power down completely, and then switch the ignition back on to clear the non-self-curing fault code.

5. 5

   Verify repair

   Start the engine to confirm the starting issue is resolved and the fault code does not reappear.