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. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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A current DTC U1305 may be retrieved only from body control module (BCM).
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A partial malfunction in the class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit. The following modules communicate on the class 2 serial data circuit. The BCM is diagnosed only through GMLAN serial data circuit.
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Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
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A poor connection at splice pack SP205 will cause this condition but will not set a DTC.
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An open in the class 2 serial data circuit between the DLC and splice pack SP205 will prevent the scan tool from communicating with any module on the class 2 network. This condition will not set a DTC.
| • | Audio-Amplifier |
| • | BCM |
| • | CD changer (CDX) |
| • | Communication interface module (OnStar®) |
| • | Digital radio receiver (DRR) |
| • | Driver door module (DDM) |
| • | Driver door switch (DDS) |
| • | Driver position module (DPM) |
| • | Fold top controller (FTC) |
| • | Head up display (HUD) |
| • | HVAC control module |
| • | Inflatable restraint sensing and diagnostic module (SDM) |
| • | Instrument panel cluster (IPC) |
| • | Passenger door module (PDM) |
| • | Radio |
| • | Remote control door lock receiver (RCDLR) |
| • | Steering column lock control module (SCLCM) |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Data Link Connector Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Are the DTCs U1300, U1301, or U1305 retrieved from any module? | Go to Step 3 | ||
Did the scan tool communicate with any module on the class 2 serial data circuit? | Go to Step 4 | Go to Step 7 | |
4 | Did you record any DTCs in the range of U1000-U1255? | Go to Step 5 | Go to Step 6 |
5 | Did you record any DTCs in the range of U1001-U1254? | Go to DTC U1001-U1254 | Go to DTC U1000 and U1255 |
6 | Diagnose the non-communicating module by using the DTC U100-U2154 procedure for the module which is not communicating. Refer to DTC U1001-U1254 . Did you complete the action? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | -- |
Did you find and correct the condition? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 8 | |
8 | Test the DLC ground circuit at terminal 5 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 9 |
Did you find and correct the condition? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 10 | |
Repair the class 2 serial data circuit between the DLC and the splice pack SP205 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the action? | System OK | -- | |
