New Holland 18003 – ACM: Hand Throttle #2 Voltage Too Low

The Armrest Control Module (ACM) has detected that the voltage from the Hand Throttle #2 sensor is below the expected operational range. This low voltage signal prevents the controller from accurately determining the operator's desired engine speed, which can negatively impact throttle response and overall tractor performance. The underlying cause is typically an electrical failure, such as a short circuit to ground or a faulty throttle position sensor.

• T8.275
• T8.300
• T8.330
• T8.360
• T8.390
• T8.420
• Magnum 235
• Magnum 340

1. 1

   Verify battery voltage is fully charged (above 12.6V) and all main ground connections to the chassis are clean and tight to prevent erroneous codes.

2. 2

   Inspect the wiring harness between the armrest controller and hand throttle assembly for chafing, corrosion, or pinched wires.

3. 3

   Gently pull on each wire in the connector near the armrest plug to check for internal breaks (a 'stretchy' wire indicates an internal break).

4. 4

   Test the Throttle Position Sensor (TPS) for a stable 5-volt reference supply from the controller and a solid ground connection.

5. 5

   Measure the TPS signal voltage with a multimeter while moving the hand throttle from idle to full (voltage should change smoothly from approximately 0.5V to 4.5V).

6. 6

   Check for other active or stored fault codes (e.g., 2053 and 2054) that might indicate a broader 5-volt reference circuit issue.

1. 1

   Isolate the Fault

   Based on the diagnostic checks, determine if the fault lies with the wiring, the sensor, or the armrest control module.

2. 2

   Repair Wiring

   If a wiring issue is found, repair the damaged section of the harness. Ensure all connections are clean, secure, and properly insulated.

3. 3

   Replace the Hand Throttle Sensor

   If the sensor is identified as the faulty component, it will need to be replaced. The sensor is often part of a larger throttle assembly.

4. 4

   Replace the Armrest Control Module

   If both the wiring and the sensor are confirmed to be in good working order, the Armrest Control Module (ACM) may be at fault. This is often the most expensive component, so it should be the last item to be replaced. In some cases, these modules can be sent for repair.

5. 5

   Clear Fault Codes

   After completing the repairs, clear all stored fault codes using the tractor's diagnostic system or an EST.

6. 6

   Calibrate and Test

   After replacing components like the throttle sensor or controller, a calibration procedure may be necessary. Operate the tractor and verify that the hand throttle functions correctly and that the fault code does not reappear.