Circuit/System Description
Battery voltage is applied at all times to the body control module (BCM) from the INT LAMPS Fuse located in the rear fuse block. The BCM then applies this voltage to the following lamps
- Courtesy reading lamps
- Dome lamp
- Rear compartment courtesy/cargo lamp
- Vanity mirror lamps
In the event that any of these lamps were to remain illuminated for more the 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps circuit to prevent total battery discharge.
The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying battery positive voltage to the front fog lamps relay control circuit when the front fog lamp relay is energized, battery positive voltage is applied to the front fog lamps supply voltage circuit which illuminates the front fog lamps.
The backup lamp relay is controlled by the body control module (BCM). The BCM provides ground to the backup lamp relay control circuit in order to turn ON the backup lamp relay. When the backup lamp relay control circuit opens, becomes shorted to voltage, or becomes shorted to ground without being commanded ON by the BCM, DTC B2545 is set.
The INTERIOR LIGHTS fuse supplies battery voltage to the body control module (BCM). The BCM applies battery voltage to the courtesy reading and dome reading lamps through the courtesy lamp supply voltage circuit. The dome/reading lamps are controlled by a 3 position (OFF, DOOR, ON) switch. When the dome/reading lamp switch is placed in the DOOR position the lamps are controlled by the BCM. When any door is opened, the jam switch contacts close and the BCM receives a door-open input. If the BCM receives a door lock or unlock input the BCM will activate the courtesy lamp supply voltage circuit, providing battery voltage to the dome/reading lamps. The BCM shall provide a Parade Mode feature intended to allow the dimming level of certain vehicle displays to remain bright enough for convenient daylight viewing if the park lamps or headlamps are turned on during daylight conditions. The BCM shall provide a Day/Night Mode Determination feature designed to determine whether the vehicle is operating in ambient light conditions consistent with day or night driving. If the BCM is currently in the Day Mode and the LIGHT input indicates the ambient light level has been continuously below the current DNT (day night transition) for the last 15 seconds (Ambient Light Day - Night Timer calibration), the BCM shall enter the Night Mode of operation. If the BCM is currently in the Night Mode and the LIGHT input indicates the ambient light level has been continuously above the current NDT (night day transition) for the last 30 seconds (Ambient Light Night - Day Timer calibration), the BCM shall enter the Day Mode of operation.
The body control module (BCM) turns on the LOW BEAM relay when the ambient light sensor senses a dark condition or the low beam headlamps are requested ON. Battery positive voltage is supplied to the LOW BEAM relay at all times. The BCM grounds the LOW BEAM relay control circuit in order to activate the relay.
The high beam relay is controlled by the body control module (BCM). The BCM provides ground to the high beam relay control circuit in order to turn ON the high beam relay. When the high beam relay control circuit opens, becomes shorted to voltage, or becomes shorted to ground without being commanded ON by the BCM, DTC B2580 is set.
The body control module (BCM) turns on the PARK LAMP relay when the ambient light sensor senses a dark condition or the park lamps are requested ON. Battery positive voltage is supplied to the PARK LAMP relay at all times. The BCM grounds the PARK LAMP relay control circuit in order to activate the relay.
The body control module (BCM) monitors the instrument panel (I/P) lamps dimming control circuit to determine the lighting intensity of the I/P lamps. When the BCM receives a varied voltage signal on the I/P lamps dimming control circuit, it applies a corresponding pulse width modulated (PWM) voltage signal through the I/P lamps supply voltage circuit to all the I/P lamps.
The body control module (BCM) monitors the ambient light sensor signal circuit in order to determine if the daytime running lights (DRL) or the automatic lamp control (ALC) should be turned ON in the AUTO mode. When the BCM senses the ambient light sensor voltage is between 1.75-4.9 volts, either the DRL will be commanded ON or the ALC will be commanded ON.
The body control module (BCM) supplies voltage to the center high mount stop lamp (CHMSL) and the powertrain control module (PCM) when the stop lamps are active.
The body control module (BCM) controls the left front turn signal, hazard lamp, and daytime running lamp (DRL). The BCM supplies voltage to control the lighting functions. The BCM monitors the left turn signal lamp supply voltage circuit for proper operation.
The body control module (BCM) controls the right front turn signal, hazard lamp, and daytime running lamp (DRL). The BCM supplies voltage to control the lighting functions. The BCM monitors the right turn signal lamp supply voltage circuit for proper operation.
The body control module (BCM) controls the left rear turn signal and hazard lamp. The BCM supplies voltage to control the lighting functions. The BCM monitors the left rear stop/turn lamp supply voltage circuit for proper operation.
The body control module (BCM) controls the right rear turn signal and hazard lamp. The BCM supplies voltage to control the lighting functions. The BCM monitors the right rear stop/turn lamp supply voltage circuit for proper operation.
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).
The R-BEC 1 fuse in the underhood fuse block supplies battery positive voltage to the BACKUP LAMP relay through the BACKUP LAMP fuse. When the gear selector is placed in reverse, the body control module (BCM) supplies ground to the BACKUP LAMP relay. This energizes the BACKUP LAMP relay and current flows from the BACKUP LAMP relay to the backup lamps and then to ground. The backup lamps are grounded at G401 and G403.
The courtesy lamp high control circuit supplies voltage to the courtesy lamps and cargo lamps. The lamps are illuminated when they receive a battery positive voltage from the courtesy lamp high control circuit of the body control module (BCM). The BCM will supply voltage to the courtesy lamp high control circuit for illuminated entry under the following conditions
- The ignition is in the LOCK position.
- The I/P dimmer switch is in the door position.
- The door jamb input transitions to an active state (opening a door).
- The use of the RKE to unlock the side doors
When the driver uses the remote function actuator transmitter to unlock the doors, the BCM will illuminate the courtesy lamps for approximately 40 seconds, unless another BCM function causes the lamps to remain active. If the ignition switch is turned to either the RUN or START position, the courtesy lamps will turn OFF immediately. When the door latch switch signal circuit is active with the ignition in the OFF position, the BCM will illuminate the courtesy lamps. The courtesy lamps will remain illuminated for approximately 25 seconds after the door latch switch signal circuit becomes inactive, unless another BCM function causes the lamps to remain active. If the ignition switch is turned to either the RUN or START position, the courtesy lamps will turn OFF immediately.
The ambient light sensor is used to monitor outside lighting conditions. The body control module (BCM) provides a 5-volt reference signal to the ambient light sensor. The sensor is a variable resistor, it's resistance changes as outside lighting conditions changes. With the headlamp switch in the AUTO position, the BCM monitors the sensor signal circuit to determine if the outside lighting conditions are correct for either daytime running lamps (DRL) or headlamp low beam operation. In daylight conditions, the BCM will command the DRLs ON. In low light conditions, the BCM will command the low beam headlamps ON.
With the ignition switch in the ON position, and the park lamps or low beam headlights ON, the fog lights will illuminate when the driver presses the fog lamp switch. The FRT FOG fuse in the underhood fuse block supplies battery positive voltage to the switch side of the FRT FOG relay. When the fog lamp switch is pressed, the body control module (BCM) fog lamp switch input is grounded. Ground is provided at G203. The BCM will then energize the FRT FOG relay control circuit. The current flow is now from the FRT FOG relay to both front fog lamps and to ground. Ground is provided at G101 and G102. The state of the fog lamps, either ON or OFF, will remain the same until the fog lamp switch is pressed again, or the ignition switch is cycled OFF and ON. Fog lamp operation will be cancelled whenever the park lamps, are turned OFF or the high beam headlights have been selected.
The headlamps may be turned ON 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the AUTO position, for automatic lamp control (ALC). During ALC, the headlamps will be OFF in daylight conditions, or low beam operation in low light conditions. Battery positive voltage is supplied to the low beam relay and the high beam relay in the underhood fuse block. When low beam headlamps are requested, the body control module (BCM) supplies ground to the coil side of the low beam relay. This activates the relay and the relay supplies voltage to the left hand low beam headlamp through the LH LOW BEAM fuse and to the right hand low beam headlamp through the RH LOW BEAM fuse. Ground for the left hand low beam headlamp is provided at G101. Ground for the right hand low beam headlamp is provided at G102. When high beam headlamps are requested, the body control module (BCM) supplies ground to the coil side of the high beam relay. This activates the relay and the relay supplies voltage to the left hand high beam headlamp through the LH HIGH BEAM fuse and to the right hand high beam headlamp through the RH HIGH BEAM fuse. Ground for the left hand high beam headlamp is provided at G101. Ground for the right hand high beam headlamp is provided at G102.
The ambient light sensor is a light sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes to the outside (ambient) light level. When the BCM receives this signal, it will either turn ON the daytime running lamps (DRL) or the headlights if the headlamp switch is in the AUTO position. Any function or condition that turns ON the headlights will cancel the DRL operation. With the headlight switch in the AUTO position, the headlights will either be turned ON or OFF, after an approximate 30 second delay depending on whether daylight or low light conditions are sensed. The DRL illuminates the park/turn signal lamps. The DRL will operate when the ignition switch is in the ON position, the gear selector is not in the PARK position, and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate. DRL operation in manual transmission equipped vehicles will occur when the ignition switch is in the ON position, and the parking brake is released.
The body control module (BCM) is responsible for the dimming of the interior lights. The BCM receives a varying signal from the I/P dimmer switch. Based on the position of the I/P dimmer switch, the BCM then supplies the appropriate amount of voltage to the interior lamps. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turns ON at the dimming level indicated by the I/P dimmer switch. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting, respond from minimum intensity to maximum brightness in response to the I/P dimmer switch position.
The park, tail, and marker lamps, including the license lamps, are turned ON when the headlamp switch is placed in the PARK or HEADLAMP position, or anytime the headlights are requested. The PARK LAMPS fuse in the rear fuse block supplies battery positive voltage to the PARK LAMP relay switch contacts. The PARK LAMPS fuse in the rear fuse block also supplies battery positive voltage to the PARK LAMP relay coil. When the park lamps are turned ON, the body control module (BCM) energizes the park lamp relay. Current flow is from the PARK LAMP relay to their respective park and marker lamps and to ground. Ground is provided at G101, G102, G401, and G403.
The body control module (BCM) is responsible for controlling the stop lamps. When the driver presses the brake pedal, the BCM will receive a signal from the brake pedal position sensor. The BCM then supplies battery positive voltage to both left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The stop lamps are grounded at G401 and G403. The CHMSL is grounded at G302.
The body control module (BCM) is responsible for controlling the turn signals and hazard lamps. When the turn signal switch is placed in either the left turn or right turn position, the BCM receives a signal from the turn signal switch. The BCM then sends an on-off voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, the BCM receives a signal from the hazard switch. The BCM then will send an on-off voltage signal to all the turn signal lamps. All the turn signal lamps will flash including both IPC turn signal indicators.