For 1990-2009 cars

### Body Control Module (BCM)

The body control module (BCM) controls the following reminders:

Key-in-ignition reminder: An audible warning intended to remind the driver that the key is in the ignition cylinder. The BCM sounds the chime for this reminder at a rate of 135-165 chimes per minute.
Fasten-seat-belt reminder: An audible warning indented in order to remind the driver at the beginning of the driving cycle that the driver seat belt is unfastened. The BCM sounds the chime for this reminder at a rate of 45-55 chimes per minute.
Fasten-belts indicator control: A visual warning intended to reminded the driver that the driver seat belt is unfastened.
Turn-signal reminder: An audible warning intended to remind the driver that the turn signal has been left on while the vehicle has traveled over 1.2 km (¾ mi). The BCM sounds the chime for this reminder at a variable rate (in unison with the turn lamps) of 50 chimes per minute.
Headlamps-ON reminder: An audible warning intended to remind the driver that the headlamps have been left on. The BCM sounds the chime for this reminder at a rate of 180-220 chimes per minute.
Last-door-closed locking confirmation: An audible warning intended to provide the driver feedback that the last-door-closed locking feature is active.
Feature customization and diagnostics feedback: An audible feedback used when changing feature customization modes. This feedback is also used by service technicians during BCM diagnostics. The BCM sounds the chime and turns on/off the fasten-belts indicator during feature customization, and also during diagnostics.

### Key-in-Ignition Reminder

The BCM sounds the key-in-ignition reminder when the following conditions are met:

• | The driver door is open (ground signal in CKT 159).

• | The key is fully inserted in the ignition cylinder (ground signal is CKT 80).

• | The ignition switch is in one of the following positions:

- | LOCK

- | ADD

- | OFF

### Fasten-Seat-Belt Reminder

The BCM sounds the fasten-seat-belt reminder for approximately 6 seconds when the following conditions are met:

• | The ignition switch is turned from the LOCK position or the OFF position, to the RUN position.

• | The driver seat belt is unfastened (ground signal in CKT 238).

If the driver fastens the seat belt during the chime period, the BCM stops the chime. If the driver unfastens the seat belt within 6 seconds, the BCM resumes the chime for the remainder of the 6-second period.

### Fasten-Belts Indicator Control

The BCM turns on the fasten-belts indicator for 63-77 seconds by sending B+ through CKT 529 when the following conditions are met:

• | The ignition switch is in the RUN position.

• | The driver seat belt is unfastened (ground signal in CKT 238).

If the driver fastens the seat belt during the 70-second period, the BCM turns off the indicator. If the driver unfastens the seat belt during the same ignition cycle, the BCM repeats the cycle, turning on the fasten-belts indicator for an additional 63-77 seconds.

### Turn Signal Reminder

The BCM sounds the turn signal reminder once per each flash of the turn signal lamps when the following conditions are met:

• | The ignition switch is in the RUN position.

• | The turn signal switch is in either turn position, sensing, within 1 second, an open to B+ transition in one of the following circuits:

- | CKT 18

- | CKT 19

• | The vehicle has traveled a distance of 1.2 km (¾ mi) by counting pulses on the vehicle speed input CKT 389.

The BCM keeps active the turn signal reminder until one of these conditions is met:

• | The ignition switch is turned to the LOCK position or to the OFF position

• | The turn signal switch returns to the OFF position, sensing, within 1 second, no transitions from open to B+ in either of the following circuits:

- | CKT 18

- | CKT 19

### Headlamps-On Reminder

The BCM sounds the headlamps-on reminder when the following conditions are met:

• | The driver door is open (ground signal in CKT 159).

• | The headlamp switch is in either PARK position or HEAD position (open in CKT 1872).

• | The key is removed from the ignition switch (open in CKT 80).

### Last Door Closed Locking Confirmation

Refer to Automatic Door Locks for additional information regarding the last door closed locking feature.

### BCM Inputs and Outputs

#### Key-in-Ignition Switch Input

The BCM interfaces with the ignition key alarm switch. The ignition key alarm switch grounds CKT 80 when the key is fully inserted in the ignition switch. The switch opens when the key is removed from the ignition switch. The BCM uses this input for the operation of the key-in-ignition reminder. The ignition key alarm switch receives ground through CKT 1550.

#### Driver-Door-Ajar Switch Input

The BCM uses this input for the operation of the key-in-ignition reminder and the headlamps-on reminder. When the driver door is open, the door lock switch grounds CKT 159. The door lock switch receives ground through CKT 750. Refer to Body Control Module (BCM) for more information regarding the driver-door-ajar switch input.

#### Driver-Seat-Belt Switch Input

The BCM determines when the driver seat belt is fastened through the seat belt switch. The seat belt switch opens when the driver fastens the seat belt. When the driver unfastens the seat belt, the seat belt switch closes. This causes the switch to ground CKT 238. The seat belt switch receives ground through CKT 750. The BCM uses this input for the operation of the fasten-belts indicator lamp and the fasten-belts chime reminder.

#### Left/Right-Turn-Signal Input

The BCM determines that the turn signal switch is ON by sensing a transition from open to B+ in one of the following circuits:

• | CKT 18 (left turn signal)

• | CKT 19 (right turn signal)

The BCM determines that the turn signal switch is off by sensing a constant open or B+ in one of the following circuits:

• | CKT 18

• | CKT 19

The BCM uses this input for the operation of the turn signal reminder.

#### Vehicle Speed Input

The BCM determines the vehicle traveled distance by interfacing with the vehicle speed CKT 389. This circuit grounds 4000 times as the vehicle travels 1.6 km (1.0 mph). The BCM uses this input for the operation to the turn signal reminder.

#### Park Lights Off Input

The BCM senses a voltage signal through the park lights off input (CKT 1872) when the headlamp switch is in the OFF position. This circuit opens when the headlamp switch is in one of the following positions:

• | The PARK position

• | The HEAD position

The headlamp switch receives B+ through CKT 1340. The BCM uses this input for the operation of the headlamps-on reminder.

#### Fasten-Belt Indicator Control Output

The BCM uses this output for the operation of the fasten-belts indicator. The BCM applies voltage to CKT 529, turning ON the fasten-belt indicator. The fasten-belts indicator is grounded at all times through CKT 1450.