DTC U1300: Class 2 Short To Ground: Description

WARNING: This page is about a different car, the 2001 Cadillac Seville. However, it is still accessible from the selected car via links, so may be relevant.

Class 2 serial data line is used to communicate information between modules. Each module connected to serial data line is assigned its own recognition code (address). This DTC is used to identify which modules are communicating. Modules communicate with each other by periodically sending State Of Health (SOH) messages. When ignition switch is in RUN position, each module communicating on serial data line sends a SOH message every 2 seconds to ensure that system is operating properly. This module monitors serial data line for a short to ground. If module detects a short to ground for longer than 3 seconds, no communication will be established between this module and other modules, causing DTC U1300 to be stored. A current DTC will clear when a valid class 2 message is detected on class 2 serial data circuit, or at end of current ignition cycle. A history DTC clears after 50 consecutive ignition cycles without a repeat of malfunction.