Audible Warnings Circuit Description. Chevrolet PJJ 2000

For 1990-2009 cars

### Radio Chime Circuits

All chimes are activated by the Body Control module (BCM) by class 2 messages. Via the radio according to messages it receives on the class 2 serial data line. The radio sends the required chime signals to the radio amplifier, which sounds the chime through the Drivers door speaker. The chime will sound with the radio turned off or on.

### Fasten Belts Chime

If the driver's seat belt is unbuckled, the drivers front seat belt switch closes, which applies a ground signal input to the sensing and diagnostic module (SDM). The SDM sends a message on the Class 2 serial data line to the body control module (BCM), indicating that the seat belt switch is closed. When the ignition switch is turned to START or ON, the BCM sends a message on the class 2 to the IPC initiating the fasten seat belts warning. The IPC illuminates the FASTEN BELTS indicator for up to 72 seconds. At the same time, the BCM sends a message on the class 2 serial data line requesting the radio to activate the five-pulse fasten belts chime. If the driver's seat belt is buckled during the 50 pulse/min chime period, the chime stops and the indicator turns off.

### Key in Ignition Chime

The Key In Ignition Warning chime sounds when the key is in the ignition, not in the ON or START position and the Drivers door is open. Inserting a key in the ignition switch closes the ignition key warning switch, which applies a ground input to the Body Control Module (BCM). The BCM sends a message on the class 2 serial data line to the radio, signalling that the key in ignition switch is closed. Opening the drivers front door closes the door jamb switch. If the conditions to activate the chime are met, the BCM sends a message on the Class 2 serial data line requesting the radio to activate the key in ignition chime.

### Lamps On Chime

The lamps on chime activates with the headlamp switch in HEAD or PARK position, the Drivers door open and the ignition switch in OFF or ACC. When the headlamp switch is in HEAD or PARK, switch contacts close to provide a ground input on the corresponding circuit to the BCM, which in turn, turns on the lamps. Opening the drivers front door closes the door jamb switch. The BCM sends a message to the radio on the class 2 serial data line, signalling that the conditions to activate the chime are met for the radio to activate the Lamps On chime.

### Park Brake Warning Chime

The park brake warning chime activates when the body control module (BCM) receives a ground signal from the park brake switch and a class 2 message from the powertrain control module (PCM) indicating the vehicle speed is higher than the calibrated value with the park brake switch in the active state. The BCM will then send a class 2 message to the IPC illuminating the park brake indicator and send a class 2 message to the radio activating the chime.