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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 2.8L (LWN) Diesel - Diagnostic Information And Procedures (3 Of 3)) >> Diagnostic Information and Procedures >> Fuel Heater Diagnosis >> Circuit/System Description

Circuit/System Description

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Ignition voltage is supplied to the coil side of the fuel heater relay whenever the ignition is ON. The Engine Control Module (ECM) provides a ground to control the fuel heater relay. When the ECM is commanding the fuel heater On, the voltage of the control circuit should be low, near 0 V. When the ECM is commanding the fuel heater Off, the voltage of the control circuit should be high, near battery voltage.