Case IH 2558 – Engine Control Module (ECM): Auxiliary PWM Driver 1 Circuit Voltage too low

The Engine Control Module (ECM) has detected a low signal voltage or a short to ground on the analog torque signal circuit, which is designated as the Auxiliary PWM Driver 1.

• MX Magnum
• MX Magnum Series
• TG Series
• T8000 Series
• Puma
• Steiger
• Axial-Flow 5088
• Axial-Flow 6088
• Axial-Flow 7088

1. 1

   Verify Code Status: Check if Fault Code 2558 is currently active or inactive using a diagnostic display.

2. 2

   Software Configuration Check (Misconfiguration cause): Check the ECM settings. If the specific tractor/transmission combination does not utilize an electronic transmission shift modulator, the default setting might be incorrectly turned on.

3. 3

   Harness Inspection (Wiring cause): Inspect the OEM wiring harness running between the ECM and the transmission shift modulator for an open circuit, short pin-to-pin, or short to ground.

4. 4

   Return Circuit Check (Wiring cause): Trace the return circuit to ensure it is properly wired back to the ECM or grounded to the engine block/chassis.

5. 5

   Component Testing (Component failure cause): Test the resistance of the transmission shift modulator to see if it has failed internally.

1. 1

   Adjust ECM Parameters

   If the machine does not feature a compatible electronic transmission shift modulator, connect the electronic service tool (INSITE) and change the 'Transmission PWM Output Type' setting to NONE. This will often clear the fault code immediately.

2. 2

   Repair Wiring

   If the machine does use the modulator, disconnect the harness at both the ECM and the modulator. Use a multimeter to check for continuity and shorts to ground. Repair any chafed wires or replace damaged connector pins (using appropriate Deutsch, AMP, or Metri-Pack test leads to avoid pin damage).

3. 3

   Replace the Modulator

   If the wiring is intact but the transmission shift modulator fails its resistance test or is physically damaged, remove and replace the modulator.

4. 4

   Clear Codes

   Reconnect all components, turn the keyswitch to the ON position, and use the diagnostic tool to clear the inactive fault codes. Verify that the code does not return during operation.