New Holland ENG 2558 – Engine Control Module (ECM): Auxiliary PWM Driver 1 Circuit Voltage too low

The Engine Control Module (ECM) has detected a voltage that is below normal or shorted to a low source (ground) on the Auxiliary PWM Driver #1 circuit.

• New Holland T8000 Series Tractors
• New Holland CR Series Combines (CR9040, CR9060, CR9070, CR9080)

1. 1

   Verify ECM Configuration: Connect the electronic service tool to check if the Auxiliary PWM Driver 1 is configured for use on this specific machine.

2. 2

   Check for Active vs. Inactive Codes: Determine if the code is currently active. If inactive, it may be an intermittent wiring issue.

3. 3

   Inspect the OEM Wiring Harness: Locate the harness running from the ECM to the auxiliary device and inspect for chafing, pinched wires, or exposed copper shorting to the chassis.

4. 4

   Test Circuit Continuity: Disconnect the harness at both the ECM and the auxiliary device. Use a multimeter to check for a short pin-to-pin or a short to ground on the output device driver line and the return line.

1. 1

   Address Configuration Issues

   If your specific machine does not utilize an Auxiliary PWM Driver 1, use the electronic service tool to change the output type setting (e.g., Transmission PWM Output Type) to 'NONE'. This will clear the fault code if it was caused by a software configuration mismatch.

2. 2

   Repair or Replace Wiring

   If the multimeter test reveals a short to ground in the OEM wiring harness, locate the damaged section. Repair the wiring using proper splicing techniques and heat shrink, or replace the affected harness section entirely.

3. 3

   Test the Auxiliary Device

   If the wiring tests good, the short to ground may be internal to the auxiliary device itself (e.g., the transmission shift modulator). Test the resistance of the device according to the specific machine's service manual. If it fails, remove and replace the component.

4. 4

   Clear Codes and Verify

   Reconnect all harnesses. Turn the key switch to the ON position, connect the diagnostic tool, and clear the inactive fault codes. Run the machine to verify the code does not return and that the transmission/auxiliary functions operate correctly.