JCB 0x00 – ECM: SCV High Voltage Fault

The Engine Control Module (ECM) has detected an abnormally high voltage in the electrical circuit for the Suction Control Valve (SCV). The SCV controls the amount of fuel entering the high-pressure fuel pump. A high voltage condition indicates a potential short circuit to a power source, a faulty SCV, or an issue within the ECM's driver circuit. When active, this fault typically causes a reduction in engine torque and may be followed by a delayed engine stop.

• JS210
• JS220
• Ecomax 4.4L Tier 4
• Ecomax 4.8L Tier 4

1. 1

   Retrieve fault codes using a diagnostic scanner to confirm the presence of this code and note any other active codes

2. 2

   Visually inspect the wiring harness and electrical connector for the Suction Control Valve for chafing, cuts, melting, or a short to a power source

3. 3

   Check the SCV connector for corrosion, bent pins, or a loose connection

4. 4

   Check battery voltage to ensure the charging system is not overcharging, which could contribute to high voltage faults

5. 5

   Verify fuel levels are adequate and fuel is not contaminated

1. 1

   Connector Voltage Test

   Disconnect the SCV electrical connector. With the ignition on, use a multimeter to test for proper voltage being supplied to the connector from the ECM. A wiring diagram for the specific machine is highly recommended for identifying the correct pins for power, ground, and signal. An abnormally high voltage reading on the signal wire points towards a short circuit in the harness.

2. 2

   Wiring Integrity Check

   Check for a short to power in the control circuit. With the connector unplugged from the SCV and the ECM, test for continuity between the control wire and a known-good power source. There should be no continuity. Also, check the resistance of the wire from the ECM connector to the SCV connector to ensure it is not open or has high resistance.

3. 3

   SCV Solenoid Resistance Test

   Use a multimeter set to Ohms to measure the internal resistance across the terminals of the SCV solenoid itself. Compare this reading to the manufacturer's specifications. A reading that is out of specification indicates a faulty solenoid, requiring replacement of the SCV.

4. 4

   Component Replacement

   If the wiring is confirmed to be in good condition and the SCV solenoid is out of specification, the Suction Control Valve must be replaced.

5. 5

   Final System Check

   After replacing the SCV or repairing the wiring, clear the fault codes using a diagnostic scanner and perform a key cycle. Start the engine and allow it to run to confirm that the fault does not return.