Diagnostic Aids
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- The diagnostic procedure used for DTC U1500 in Onstar® systems with single module generations of Onstar® differ greatly from previous generations with two modules. While these older generations denoted a failure of the three wire bus between the modules by setting a U1500, single module Onstar® systems use this DTC to denote an internal module failure. The determination of whether a one or two module generation of Onstar® is used should be confirmed. Refer to ONSTAR Description And Operation .
- This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the VCIM.
- If this DTC is retrieved as both a current and history DTC, replace the VCIM.