Orlando

DTC U0002

Control modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the control modules. The control modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.

A supervised periodic message that includes the transmitter module availability has not been received.

The control module uses a default value for the missing parameter.

Schematic Reference

Data Communication Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

With a scan tool, attempt to communicate with all control modules.

1. With a scan tool, verify DTC U0100-U02FF or U2105-U2199 is not set as current.

⇒	If DTC is set, refer to DTC U0100-U02FF or DTC U2105-U2199 .

2. Ignition OFF, disconnect the applicable control module harness connector.
3. Ignition OFF, test for less than 5 Ω between the applicable control module ground circuit and ground.

⇒	If greater than the specified range, test the circuit for an open/high resistance.

4. Ignition ON, verify a test lamp illuminates between the following circuits of the applicable control module and ground:

•	The battery positive voltage input circuits

•	The battery positive voltage output circuits

•	The ignition voltage input circuits

•	The ignition voltage output circuits

•	The switched battery positive voltage supply circuits

⇒	If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit fuse is open, test the circuit for a short to ground. If the circuit tests normal, replace the applicable control module.

5. Ignition OFF, test for less than 5 Ω between the non-communicating control module GMLAN serial data circuits and the control module reporting DTC U0002.

⇒	If greater than the specified range, test the circuit for an open/high resistance.

6. If all circuits test normal, replace the applicable control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.