Case IH t7B – Pump Control Unit (PCU): EEPROM Checksum In PCU, Data Valid But Above Normal Range

This fault code indicates an internal memory (EEPROM) checksum error within the Pump Control Unit (PCU). When this code is triggered, the engine enters a "limp home" condition: engine performance is reduced, fuel quantity is restricted, and engine speed is limited to 1300 RPM.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Inspect the wiring harness and connectors between the EEM2 controller and the Bosch VP PCU for corrosion, loose pins, or damage

2. 2

   Test the engine shut-down relay (K5) and the engine control module main relay (K7) for voltage drops that can trigger memory faults

3. 3

   Cross-test the PCU functionality by temporarily connecting a known-good EEM2 controller (Note: this will trigger a pump serial number mismatch code, but if t7B persists, the PCU is damaged; if it disappears, the original EEM2 is at fault)

1. 1

   Disconnect battery

   Disconnect the tractor's battery before servicing the engine electronics.

2. 2

   Inspect and clean connectors

   Inspect and clean the main connectors at the PCU and EEM2. Replace any damaged wiring.

3. 3

   Swap relays

   Locate relays K5 (Engine shut-down) and K7 (ECM main relay) in the fuse/relay panel. Swap them with known-good relays of the same amperage to see if the code clears.

4. 4

   Confirm PCU failure

   If the wiring and relays are intact and the cross-test confirms a failed PCU, the Bosch VP injection pump's control unit is damaged.

5. 5

   Remove and repair/replace pump

   Remove the injection pump/PCU assembly. Because the PCU is integral to the Bosch VP44 injection pump, it typically must be sent to a certified Bosch diesel injection shop for a module rebuild, or the entire pump must be replaced.

6. 6

   Couple serial number

   After reinstalling a repaired/replaced pump or a new EEM2 controller, you must use the EEM2 Service Tool to couple the injection pump's serial number to the EEM2 controller to resolve any mismatch codes.