Circuit Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. When the module detects one of the following conditions on the class 2 serial data circuit for approximately 3 seconds, the setting of all other class 2 serial communication DTCs is inhibited and a DTC will set.
DTC U1300, U1301, or U1305 Diagnostic Test
| DTC | Condition |
|---|---|
| U1300 | Low voltage on the class 2 serial data circuit. |
| U1301 | High voltage on the class 2 serial data circuit. |
| U1305 | Either high or low voltage on the class 2 serial data circuit. Some modules will set DTC U1305 if they are not capable of distinguishing between a short to battery voltage or ground. |