Test Description
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
- 2. 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:
Important : The modules listed below vary with option content on the vehicle. Skipping steps may be necessary if a module is not present on the vehicle.
- HVAC control module (HCM)/Electronic climate control module (ECCM)
- Rear climate control (RCC)
- Transfer case shift control module (TCSCM)
- Electronic brake control module (EBCM)
- Powertrain control module (PCM)
- Liftgate module (LGM)
- 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)
- Passenger door module (PDM)
- Driver seat module (DSM)
- Passenger seat module (PSM)
- Inflatable restraint sensing and diagnostic module (SDM)
- 3. The following DTCs may be retrieved with a history status:
- U1300
- U1301
- U1305
These DTCs are not the cause of the present condition.
- 4. A State of Health DTC with a history status may be present along with a U1000 or U1255 having a current status. This indicates that the malfunction occurred when the ignition was ON.
- 5. DLC terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
- 7. A poor connection at terminal H of star connector #1 or terminal F of star connector #2 could cause this condition.
- 8. An open in the class 2 serial data circuit between the DLC and star connector #1 will prevent the scan tool from communicating with any module. An open between star connector #1 and the star connector #2 will prevent the scan tool from communicating with modules connected to star connector #2.
- 9. The class 2 serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wiring for a short, make sure there is not a module connected to the wire being tested. This test isolates the Passlock™ sensor class 2 serial data circuit.
- 11. This test isolates the PCM class 2 serial data circuit.
- 13. This test isolates the ATC class 2 serial data circuit.
- 15. This test isolates the EBCM class 2 serial data circuit.
- 17. This test isolates the SIR class 2 serial data circuit.
- 19. This test isolates the IPC class 2 serial data circuit.
- 21. This test isolates the IRC class 2 serial data circuit.
- 23. This test isolates the RCC class 2 serial data circuit.
- 25. This test isolates the HCM/ECCM class 2 serial data circuit.
- 27. This test isolates the BCM class 2 serial data circuit.
- 29. This test isolates the VIU class 2 serial data circuit.
- 31. This test isolates the LGM class 2 serial data circuit.
- 33. This test isolates the DDM and the DSM class 2 serial data circuits.
- 35. This test isolates the PDM and PSM class 2 serial data circuits.
- 37. This test isolates the AMP class 2 serial data circuit.
- 45. If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.