Case IH 520198-04 - VCM – VCM / UCM / Air Cart Rate ECU: Cut-off solenoid supply voltage low / Internal 2.5V Ref, Voltage below normal, or shorted to low source

The control module has detected that the supply voltage or internal 2.5V reference voltage going to the cut-off solenoid has dropped below the normal operating threshold, typically due to a short circuit to ground (low source) or a compromised power supply.

• MAGNUM AFS Connect
• Puma
• Optum
• Precision Air Cart 2230
• Precision Air Cart 2280
• Precision Air Cart 2330
• Precision Air Cart 3380
• Precision Air Cart 3430

1. 1

   Stop the engine, remove the key, and relieve any hydraulic pressure before disconnecting electrical connections

2. 2

   Inspect the electrical wiring harness leading from the VCM/UCM to the cut-off solenoid for frayed insulation, pinched wires, or loose connections that could cause a short to ground

3. 3

   Using a multimeter, check the supply voltage at the cut-off solenoid connector to verify if the 2.5V reference or 12V/24V supply is present when the key is ON

4. 4

   Test the cut-off solenoid for an internal short; if the resistance is out of specification (too low), the solenoid is internally shorted and pulling the voltage down

5. 5

   If equipped with a PVED-CLS steering controller, check the off-road safety check diagnostics on the cut-off valve

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery ground cable to prevent electrical spikes.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short to ground in the harness, repair the damaged wire or replace the affected harness section.

3. 3

   Replace the Solenoid

   If the cut-off solenoid is internally shorted, disconnect its electrical pigtail, unthread/remove the solenoid from its mounting block or injection pump, and install the new solenoid. Torque to OEM specifications.

4. 4

   Replace the VCM/UCM

   If the wiring and solenoid test fine but the module is failing to output the correct voltage (internal failure), the UCM/VCM must be replaced. Disconnect the multi-pin connectors, unbolt the module, and install the replacement. (Note: A new UCM will likely need to be flashed/programmed by a dealer before use).

5. 5

   Reassembly & Testing

   Reconnect all electrical connections and the battery. Clear the fault codes using a diagnostic tool and cycle the key to verify the code does not return.