General

DTC7 Horn Relay Control Circuit Shorted To B+ Or Ground:

The Body Control Module (BCM) type 4 activates the horn and exterior lights based on:
^ Message received from the keyless entry system's Remote Control Door Lock Receiver (RCDLR) to perform the alarm mode.
^ The BCM detects a theft attempt when the content theft deterrent is in either armed or warning mode.

The BCM interfaces with the horn through the horn relay. The horn relay allows the BCM to sound the horn, providing an audio alert. The BCM energizes the horn relay (causing the horn to sound) by grounding circuit 28 during the following modes:
^ Armed mode: When the content theft deterrent is in armed mode, the BCM sounds the horn (once) for 25 ms (+/- 2 ms). The BCM sounds the horn only if the remote activation verification is in either mode 3 or 4. For more information regarding remote activation verification modes, refer to Diagnostic Aids. Diagnostic Aids

NOTE: The exterior lights also turn on during the armed mode, the BCM sounds the horn first. then flashes (once) the exterior lights.

^ Warning mode: The warning mode attempts to warn away potential intruders prior to setting off the alarm mode. The horn cycles on and off five times at a rate of 1 Hz (+/- 0.1 Hz) with a 20% (+/- 5%) active state duty cycle.

NOTE: The exterior lights also turn on and off five times during this mode, although the BCM alternates between the horn and the exterior lights.

^ Alarm mode: When the content theft deterrent is in alarm mode, the BCM sounds the horn on and off for 2 minutes (or until the alarm is disarmed) at a rate of 1.0 Hz (+/- 0.1 Hz) with a 20% (+/- 5%) active state duty cycle. The exterior lights also turn on during this mode, although the BCM alternates between the horn and the exterior lights.