Test Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The number(s) below refer to the step number(s) on the diagnostic table.
- 2: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
- 3: The symptoms list in Symptoms will determine the correct diagnostic procedure to use.
- 4: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed. At this point you have determined all DTCs applicable to the horn system. Refer to Symptoms - Horns for further horn system diagnosis. Any other codes displayed from the listed modules do not apply to horns and should be diagnosed in the applicable section.
Diagnostic System Check - Horns
| 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 in Data Link Communications |
| 2 |
|
Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (W/Immobilizer) in Data Link Communications |
| 3 | Select the BCM display DTCs function on the scan tool. Does the scan tool display any DTCs? |
Go to Step 4 | Go to Symptoms - Horns |
| 4 | Does the scan tool display any DTCs which begin with a "U"? | Go to Scan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer) or Scan Tool Does Not Communicate with Class 2 Device (W/Immobilizer) in Data Link Communications | Go to Step 5 |
| 5 | Does the scan tool display DTC B1000? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Symptoms - Horns |