Case IH 273 – Engine Control Module (ECM): Rear Pumping Control Valve current is low during 'click test'

The Engine Control Module (ECM) has detected an open circuit or abnormally low current on the rear pumping control valve return circuit (specifically Pin 15) during its diagnostic 'click test'. The rear pumping control valve is a critical component of the CAPS (Cummins Accumulator Pump System) fuel pump, responsible for pumping fuel into the accumulator and maintaining desired fuel pressure.

• MX Magnum
• STX Steiger
• MX series (e.g., MX210, MX240, MX270)
• STX series (e.g., STX325)
• Combines and Forage Harvesters using the 8.3L/8.9L CAPS engines

1. 1

   Using an electronic service tool, activate the click test for the Rear Pumping Control Valve and listen closely to the accumulator module to see if the valve physically operates.

2. 2

   Inspect the engine wiring harness between the ECM (Pin 15 / Pin A15) and the CAPS pump accumulator module for open circuits, chafed wires, or corroded connector pins.

3. 3

   Perform a Cylinder/Valve Cut-Out Test using the service tool to compare the rear pumping control valve against the front valve (Valve Close Angle should not vary by more than 15 degrees crank angle).

4. 4

   Check for concurrent codes (such as 274, 275, or 328) or if the engine dies during the cut-out test, which points to an internal accumulator module failure.

1. 1

   Repair Wiring

   If the diagnostic checks reveal an open circuit in the harness between the ECM and the CAPS pump, repair the wiring or replace the harness section.

2. 2

   Replace the Accumulator Module

   If the wiring is intact and the valve fails the click test or cut-out test (e.g., the engine dies when the valve is cut out, or VCA varies by >15 degrees), the internal valve has failed. The rear pumping control valve cannot be serviced separately; you must replace the entire CAPS Accumulator Module.

3. 3

   Clear Codes

   Reconnect all components and turn the key switch to the 'ON' position. Use the electronic service tool to clear the inactive fault codes.

4. 4

   Verify Repair

   Start the engine and let it idle for one minute. Verify that Fault Code 273 does not return to an active state.