Test Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Cadillac Escalade EXT. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step number(s) on the diagnostic table.
- 2: Lack of communication may be due to a partial malfunction or a total malfunction of the class 2 serial data circuit. The specified procedure will determine the condition.
- 5: The presence of DTCs which begin with "U" indicate some other system control module is not communicating.
Diagnostic System Check - Cellular Communication
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Install a scan tool. Does the scan tool power up? |
Go to Step 2 | Go to SCAN TOOL DOES NOT POWER UP |
| 2 |
|
Go to Step 3 | Go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE |
| 3 |
IMPORTANT:
The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.
|
Go to Step 4 | Go to POWER MODE MISMATCH |
| 4 | Select the VIU display DTCs function on the scan tool. Does the scan tool display any DTCs? |
Go to Step 5 | Go to OnStar Symptom Diagnosis |
| 5 | Does the scan tool display any DTCs which begin with a "U"? | Go to Step 6 | Go to Step 7 |
| 6 | Does the scan tool display DTC U1500? | Go to Diagnostic Trouble Code (DTC) List | Go to DIAGNOSTIC TROUBLE CODE (DTC) LIST |
| 7 | Does the scan tool display DTC B1000, B1004, B1007, or B1009? | Go to DIAGNOSTIC TROUBLE CODE (DTC) LIST | Go to Step 8 |
| 8 | Does the scan tool display DTC B1327 or B1328? | Go to DIAGNOSTIC TROUBLE CODE DEFINITIONS | Go to Diagnostic Trouble Code (DTC) List |