Circuit/System Description

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Each of the 4 valve lifter oil manifold (VLOM) solenoid windings, are connected in parallel to a fused ignition circuit, supplied by the powertrain relay, in the underhood fuse block. The control circuit for each solenoid is connected to an individual low side driver, internal to the engine control module (ECM). Each low side driver has its own fault detection circuit, which monitors the solenoid control circuit for an incorrect voltage level. If an incorrect voltage level, such as an open/high resistance, or short to ground is detected, the low side driver will turn OFF, and the fault detection circuit will communicate the condition to the central processor internal to the ECM. These DTCs will set when the ECM detects an incorrect voltage level on the ignition circuit, the solenoids, or a solenoid control circuit, after the ignition switch is turned ON. If a VLOM solenoid control circuit DTC is set, the ECM will command V8 mode, turn ON the malfunction indicator light (MIL), and turn OFF the fuel injector for that cylinder, resulting in an engine misfire.