B2752

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

CIRCUIT DESCRIPTION
CKT 28 is an input to the body control module (BCM). The BCM monitors CKT 28 in order to determine if the horn circuit is open or shorted to ground.

CONDITIONS FOR RUNNING THE DTC
- The system voltage must be between 9.0 and 16.0 volts.
- The horn must be activated to verity operation of the system.

CONDITIONS FOR SETTING THE DTC
- When CKT 28 is open or shorted to ground for approximately 3 minutes the BCM will set B2752.
- The system voltage must be between 9.0-16.0 volts.

ACTION TAKEN WHEN THE DTC SETS
- If CKT 28 is shorted to ground the horns will remain ON at all times.
- If CKT 28 is open the horn will only work with the horn button on the steering wheel.

CONDITIONS FOR CLEARING THE DTC
- A current DTC will clear immediately after the condition for setting the fault is corrected.
- A history DTC will clear after 100 consecutive ignition cycles without a fault present.
- A scan tool may be used to clear history and current DTC(s).

DIAGNOSTIC AIDS

IMPORTANT: If the customers complaint is that the horns are always on remove the HORN fuse located in the Engine Wiring Harness Junction Block. so the system can be diagnosed without the horns on.

- Always begin diagnosis with the first DTC listed on the scan tool.
- The scan tool must display DTC B2752 as a current code before performing these diagnostics.
- Inspect for a sticking horn pad and or switch.
- Perform a visual inspection for loose or poor connections at all related components.
- Refer to Testing for Intermittent and Poor Connections in Wiring Systems.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
2. Listen for an audible click when the Horn Relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the coil side of the Horn Relay.
4. Verifies that the Body Control Module (BCM) is providing ground to the Horn Relay.
5. Tests if ground is constantly being applied to the Horn Relay.
12. After replacement of the BCM you must calibrate the new module for proper operation.