B2752

Diagnostic Chart:

Schematic:

CIRCUIT DESCRIPTION
CKT 28 is an input to the body control module (BCM). The BCM monitors CKT 28 to determine if the horn circuit is shorted. CKT 28 also acts as an output to sound the horn for RFA functions.

CONDITIONS FOR RUNNING THE DTC
Voltage supplied to the BCM is within the normal operating range (aproximately 9-16 volts).

CONDITIONS FOR SETTING THE DTC
Circuit 28 is open or shorted to ground for 30 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The SERVICE VEHICLE SOON indicator illuminates.
^ If circuit 28 is shorted to ground, the horn will sound constantly.
^ If circuit 28 to the BCM is open, the BCM can not control the horn.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC B2752 clears when the malfunction is no longer present and the ignition switch is cycled.
^ A history DTC clears after 100 ignition cycles (from off to on) with no current codes active during the 100 ignition cycles.

DIAGNOSTIC AIDS
^ If the DTC is a history DTC, the problem may be intermittent. Try performing the above tests while wiggling the wiring and connectors. This can often cause the malfunction to appear.
^ Check for a sticking horn pad and/or switch.
^ Pressing and holding the horn switch for more than 30 seconds will also set this DTC.
^ Perform a visual check of the wiring and connectors.

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 and horn switch are providing ground to the horn relay.
5. Tests if ground is constantly being applied to the horn relay.