Case IH 3509-01 - ACM – ACM: 5V Sensor Supply Bank 1 Circuit Failed Low

The control module provides a 5-volt reference signal to power various external sensors. This code triggers when the module detects that the voltage on this specific 5V circuit has dropped below the normal operational range (typically shorted to ground or pulled down by a failed component).

• MAGNUM AFS Connect
• Magnum
• Steiger
• Puma
• Optum
• Axial-Flow

1. 1

   Turn the ignition off to prepare for testing.

2. 2

   Disconnect the sensors powered by the ACM's 5V Bank 1 circuit to isolate them. This typically includes the DOC inlet pressure sensor, DPF differential pressure sensor, and the DEF pressure sensor.

3. 3

   Check for a shorted sensor: Turn the ignition ON (engine OFF). Measure the voltage at the 5V supply pin on the harness side of the disconnected sensors. If the voltage returns to ~5V, one of the sensors is internally shorted. Plug them in one by one until the voltage drops again to identify the faulty sensor.

4. 4

   Check for a harness short: If the voltage is still low with all sensors unplugged, turn the ignition OFF and disconnect the main 120-pin connector at the ACM. Measure the resistance between the 5V supply pin on the sensor harness and a good chassis ground. If the resistance is less than 1k ohms, the wiring harness is shorted to ground.

5. 5

   Check the ACM: If the harness tests good (no shorts to ground) but the ACM is still not outputting 5V at the module pins, the ACM has suffered an internal power supply failure.

1. 1

   Resolve the Short

   If a sensor is faulty: Replace the specific shorted sensor (e.g., DPF pressure sensor). If the harness is faulty: Trace the 5V supply wire from the sensor connector back to the ACM. Locate the rub point, chafed insulation, or melted wire. Repair the wire using an approved splice or replace the affected harness section. If the ACM is faulty: Replace the Aftertreatment Control Module.

2. 2

   Reassemble

   Reconnect all sensors and the ACM harness.

3. 3

   Clear Codes

   Connect the Case IH Electronic Service Tool (EST) to clear the inactive 3509-01 fault code.

4. 4

   Verify Repair

   Turn the ignition ON to verify the 5V supply remains stable. Run the engine at idle for at least one minute, or perform a forced stationary regeneration to ensure the aftertreatment system operates without triggering the code.