Data Link Communication System: Overview Oldsmobile Bravada III

Data Link Communications Schematic Icons

Data Link Communications Schematic Icons Icon Icon Definition CAUTION: When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to DISABLING SYSTEM and/or ACTIVATING SYSTEM . Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs

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Test Description

The numbers below refer to the step numbers on the diagnostic table.

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1. 1. A lost communication with XXX DTC with a history status may indicate the cause of U1000 or U1255.
2. 2. The module which is not communicating is the likely cause of U1000 or U1255 being set. The following modules communicate on the class 2 serial data circuit: HVAC control module (HCM)/Electrical climate control (ECC) Rear climate control (RCC) Transfer case shift control module (TCSCM) Electronic brake control module (EBCM) Powertrain control module (PCM) Integrated radio chassis (IRC) Audio amplifier module (AMP) Vehicle interface unit (VIU) Body control module (BCM) Instrument panel cluster (IPC) Vehicle immobilizer module (VIM) Driver door module (DDM) Pass door module (PDM) Driver seat module (DSM) Passenger seat module (PSM) Liftgate module (LGM) Inflatable restraint sensing and diagnostic module (SDM)
3. 5. The module which was not communicating may have set lost communication with XXX DTCs for those modules that it was monitoring.
4. 6. The module which was not communicating may have set lost communication with XXX DTCs for those modules that it was monitoring.
5. 7. The module which was not communicating may have set lost communication with XXX DTCs for those modules that it was monitoring.
6. 11. The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.
7. 13. If all modules are communicating, the module which set U1000 or U1255 may have done so due to some other condition.
8. 14. The module which set U1000 or U1255 is the likely cause of the malfunction.

The numbers below refer to the numbers on the diagnostic table.

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1. 1. A module which loses power during an ignition cycle will cause other modules to set lost communication DTCs.
2. 2. A module which loses power during an ignition cycle will cause other modules to set lost communication DTCs.
3. 3. The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
4. 7. The module which was not communicating due to an open in the class 2 serial data circuit may have set lost communication DTCs for those modules that it was monitoring.
5. 9. The modules which can communicate indicate the module which cannot communicate. You must clear the DTCs from these modules to avoid future misdiagnosis.

The number below refers to the step number on the diagnostic table.

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1. 4. If the battery positive voltage and ground circuits of the DLC are functioning properly. The malfunction must be due to the scan tool.