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Home >> Chevrolet >> 2007 >> Chevy Express G2500, Van Cargo, 6.6 6 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 15 (Engine Control System & Fuel System - 6.6L (LLY) - DTC P0401 To DTC P2510) >> DTC P0642 or P0643 >> Circuit/System Description

Circuit/System Description

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The engine control module (ECM) supplies 5 volts to components through 5-volt reference circuits. These 5-volt reference circuits are independent of each other outside the ECM, but are bussed together in three reference groups inside the ECM. Therefore, a circuit condition on one sensor 5-volt reference circuit may affect multiple components. The ECM monitors voltage on the 5-volt reference circuits.