U1176

DTC U1176 Loss Of Communications With RFA:

DTC U1176 Loss Of Communications With RFA:

CIRCUIT DESCRIPTION
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. When a module receives a message for a critical operating parameter, the module records the ID number of the module which sent the message for State of Health monitoring (Node Alive messages). A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an ID number is learned by a module, it will monitor for that modules's "Node Alive" message. Each module on the class 2 serial data circuit which is powered and performing functions that require detection of a communications malfunction is required to send a "Node Alive" message every two seconds. When no message is detected from the Remote Function Actuator Module (RFA) for five seconds, DTC U1064 is set.

CONDITIONS FOR SETTING THE DTC
The ignition is turned to the ON position, and a module on the class 2 serial data circuit does not receive the RFA ID for 5 seconds.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC will clear when a "Node Alive" message from the RFA is detected on the class 2 serial data circuit or at the end of the current ignition cycle.
^ A history DTC can be cleared with the scan tool.

DIAGNOSTIC AIDS
When multiple Loss of Communication DTCs are set concurrently, the cause is likely to be two opens in the class 2 serial data circuit. Use the Data Link Schematic in order to determine the location of the opens.