Circuit/System Verification
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
Engine ON, check the engine speed RPM in VSES scan tool data, vary the engine RPM with the throttle while observing the instrument panel (I/P) tachometer. The I/P tachometer should change with engine speed RPM. If the I/P tach does not work correctly, replace the PCM or ECM. Refer to Control Module References .