Test Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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.
- 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.
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 in Data Link Communications |
| 3 | Select the body control module 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 in Data Link Communications | Go to Step 5 |
| 5 | Does the scan tool display DTC B1000, B1004, B1007, or B1009? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Step 6 |
| 6 | Does the scan tool display DTC B1327 or B1328? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical | Go to Diagnostic Trouble Code (DTC) List |