Circuit/System Description
When the headlamp switch is in the OFF position, the body control module (BCM) receives a ground signal through the headlamp switch OFF circuit and an open signal on the park lamp ON circuit. When the headlamp switch is in the PARK or HEAD position, the BCM receives an open signal through the headlamp switch OFF circuit and a ground signal through the park lamp ON circuit.
Voltage is applied at all times to the fog lamp relay that is soldered to the Underhood Fuseblock. When the fog lamp switch is placed in the ON position, ground is applied to the body control module (BCM) through the fog lamp switch circuit. The BCM then applies a ground to the front fog lamp relay control circuit. This engages the fog lamp relay and applies voltage through the fog lamp fuse to the front fog lamps.
When the PRNDL is placed in the REVERSE position, a signal is sent to the body control module (BCM). The BCM then applies voltage through the backup lamps voltage supply circuit to the left and right backup lamps.
Voltage is applied at all times to the low beam headlamp relay from battery voltage. The low beam headlamp relay is soldered to the Underhood Fuseblock. The replacement of the relay is accomplished by replacing the underhood fuseblock. Two different inputs to the body control module (BCM) can turn ON the low beam headlamps. The headlamp switch and the ambient light sensor.
Automatic Headlamps Operation
When the ambient light sensor detects a low light condition, the BCM then applies a ground to the headlamp low beam relay control circuit. This engages the headlamp relay and applies voltage through the headlamp fuses to the low beam headlamps.
Headlamp Switch Operation
When the headlamp switch is placed in the ON position, ground is applied to the BCM through the headlamp switch circuit. The BCM then applies a ground to the headlamp low beam relay control circuit. This engages the headlamp relay and applies voltage through the headlamp fuses to the low beam headlamps.
Voltage is applied at all times to the high beam headlamp relay from battery voltage. When the multifunction switch is placed in either the FTP or HIGH position, ground is applied to the body control module (BCM). The BCM then applies a ground to the high beam headlamp relay control circuit. This engages the relay and applies voltage through the HIGH beam fuses to both the left and right high beam headlamps.
Voltage is applied at all times to the Park Lamp Relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch signal circuit to the body control module (BCM). The BCM then applies a ground to the park lamp relay control circuit. This engages the relay that is soldered to the underhood fuseblock circuit board and applies voltage through the park lamp fuses and to all the park lamps.
The daytime running lamps (DRL) are controlled by the body control module (BCM). The BCM grounds the DRL relay control circuit in order to energize the DRL relay coil. This action places the right and left headlamps in series with each other with the DRL relay providing the ground path and the RT HDLP fuse providing battery positive voltage. The BCM monitors the low and high beam circuits to ensure that the DRLs are operating properly. If the BCM senses that the DRLs are not operating properly, DTC B2600 is set.
When the interior lamps dimming switch is activated, a variable voltage signal is applied through the instrument panel lamps dimmer switch signal circuit to the body control module (BCM). The BCM then applies a variable voltage signal through the LED backlighting dimming supply circuit to the following components
- Clock
- Diver Information center (DIC) switch
- Headlamp Switch
- HVAC Control Head
- Rear HVAC Control
- Radio
- Rear Radio Entertainment
- Steering Wheel Control Switch
Voltage for the courtesy lamps is supplied from the Interior Lights Fuse in the instrument panel I/P electrical center to the body control module (BCM). When a door is opened, a signal is applied to the door module. The door module then applies a message to the LAN communication circuit to the BCM. The BCM then applies voltage to the courtesy lamps voltage supply circuit. The courtesy lamps are composed of the following components
- Dome lamps
- Reading lamps
- Cargo Lamps
The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary depending on outside lighting conditions. The body control module (BCM) provides a 10-volt reference signal to the ambient light sensor. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the DRLs ON. In low light conditions, when the headlamps switch is in AUTO position, the BCM will command the low beam headlamps ON.
Voltage for the interior backlighting components is supplied from the CHMSL/DIMR Fuse in the instrument panel I/P electrical center to the body control module (BCM).
The BCM applies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimming switch, which is part of the headlamp switch. When the dimming switch is placed in the desired position, the dimmed voltage setting is applied from the interior lamp dimming switch through the I/P dimming return circuit to the BCM. The BCM then applies the dimmed voltage to the I/P lamps supply voltage circuit and they dim to the correct level.
The IP lamps are located in the following components
- Cigar lighter
- Driver Information Center DIC switch
- Door lock switches
- Fog Lamp switch
- Headlamp switch (turn signal multifunction switch)
- Hazard switch
- HVAC Control
- Rear HVAC Control if equipped
- I/P cluster
- Power window switch
- Power mirror switches
- PRNDL
- Radio
- Rear Seat Audio if equipped
- Steering Wheel Controls
- Sunroof switch
- Sunshade switch
- TCS switch
- Universal garage door opener switch
Battery voltage for the center high mounted stop lamp (CHMSL) is applied from the CHMSL/DIMR 15 amp Fuse in the I/P electrical center to the body control module (BCM). When the brake pedal is applied, a signal is applied to the BCM. The BCM then applies a voltage to the CHMSL voltage supply circuit to the CHMSL.
Voltage for the interior backlighting components is supplied from the CHMSL/DIMR in the instrument panel I/P electrical center to the body control module (BCM). The BCM applies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimming switch, which is part of the headlamp switch. Which is part of the turn signal multi function switch. When the dimming switch is placed in the desired position, the dimmed voltage setting is applied from the interior lamp dimming switch through the I/P dimming control circuit to the BCM. The BCM then applies the dimmed voltage to the I/P lamps supply voltage circuit and they dim to the correct level. The I/P lamps are located in the following components
- Cigar lighter
- Driver Information Center DIC switch
- Door lock switches
- Fog Lamp switch
- Headlamp switch
- Hazard switch
- HVAC Control
- I/P cluster
- Power window switch
- Power mirror switches
- PRNDL
- Radio
- Rear Seat Audio if equipped
- Rear HVAC Control if equipped
- Steering Wheel Controls
- Sunroof switch
- Sunshade switch
- TCS switch
- Universal garage door opener switch
Voltage is applied at all times to the Park Lamp Relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch signal circuit to the body control module (BCM). The BCM then applies a ground to the park lamp relay control circuit. This engages the relay and applies voltage through the park lamp fuses and to all the park lamps.
When the brake pedal is applied, the brake pedal switch normally closed contact signal circuit voltage is interrupted to the body control module (BCM). The BCM then applies a voltage to the CHMSL supply voltage circuit to the center high mounted stop lamp (CHMSL).
The body control module (BCM) applies a ground through the brake pedal position sensor (BPPS) low reference circuit to the BPPS. The BCM supplies a 5-volt reference through the brake sensor reference voltage circuit to the BPPS.
When the brake pedal is being applied, the BPPS then sends a variable voltage through the brake sensor signal circuit to the BCM.
The body control module (BCM) applies a ground through the brake pedal position sensor low reference circuit to the brake pedal position sensor (BPP). The BCM supplies a 5-volt reference through the brake sensor reference voltage circuit to the BPP. When the brake pedal is being applied, the BPP then sends a variable voltage through the brake sensor signal circuit to the BCM. The BCM then applies a signal to the brake signal circuit to the engine control module (ECM) and transmission control module (TCM).
The brake pedal position sensor (BPP) is used to sense the action of the driver application of the brake pedal. The BPP provides an analog voltage signal that will increase as the brake pedal is applied. The BPP receives a low reference signal and a 5-volt reference voltage from the body control module (BCM) when the driver applies the brakes. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop/turn signal voltage supply circuit to illuminate the stop lamps and the center high mounted stop lamp (CHMSL). The BCM also sends a BPP signal to the engine control module (ECM) as well as a serial data message to indicate the application of the brake pedal.
The brake pedal position sensor (BPP) is used to sense the action of the driver application of the brake pedal. The BPP provides an analog voltage signal that will increase as the brake pedal is applied. The BPP receives a low reference signal and a 5-volt reference voltage from the body control module (BCM) when the driver applies the brakes. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop/turn signal voltage supply circuit to illuminate the stop lamps and the center high mounted stop lamp (CHMSL). The BCM also sends a BPP signal to the engine control module (ECM) as well as a serial data message to indicate the application of the brake pedal.
When the PRNDL is placed in the REVERSE position, a GMLAN signal is sent from the transmission control module (TCM) to the body control module (BCM). The BCM then applies voltage through the backup lamps voltage supply circuit to the back up lamps.
The courtesy lamps are controlled by the body control module (BCM). Inputs from the dome lamp switch and the door ajar switches are monitored by the BCM. When a door ajar switch is closed the BCM supplies the ground for the courtesy lamps or the dome lamp switch is turned to the ON position. The BCM also supplies the voltage for the courtesy lamps.
The courtesy lamps are controlled by the body control module (BCM). Inputs from the dome lamp switch and the door ajar switches are monitored by the BCM. When a door ajar switch is closed the BCM supplies the ground for the courtesy lamps or the dome lamp switch is turned to the ON position. The BCM also supplies the voltage for the courtesy lamps.
The fog lamp fuse in the fuse block - underhood supplies battery positive voltage to the switch side of the fog lamp relay at all time. When the fog lamp switch is pressed it supplies a momentary voltage signal on the front fog lamp switch signal circuit to the body control module (BCM). The BCM then supplies ground to the coil side of the fog lamp relay energizing the relay. The fog lamp relay is soldered to the underhood fuseblock circuit board. The front fog lamps are connected to ground at G101. The park lamps or headlamps must be ON for the fog lamps to operate.
The fog lamp fuse in the fuse block - underhood supplies battery positive voltage to the switch side of the fog lamp relay at all time. When the fog lamp switch is pressed it supplies a momentary voltage signal on the front fog lamp switch signal circuit to the body control module (BCM). The BCM then supplies ground to the coil side of the fog lamp relay energizing the relay. The front fog lamps are connected to ground at G101. The foglamp relay is soldered to the underhood fuseblock circuit board. The park lamps or headlamps must be ON for the fog lamps to operate.
There is constant voltage that is supplied to the hazard switch. The hazard switch (when engaged) supplies voltage to the park/turn signal lamps. The turn signal switch in the headlamp switch portion of the turn signal multifunction switch also is provided voltage from the hazard switch circuit after the turn signal circuit. Depending on the location of the hazard switch will determine which fuse the turn/hazard circuit will be powered.
The headlamp may be turned on 2 different ways. First, when the driver places the headlamp switch in the ON position, for manual operation. Second, with the headlamp switch placed in the OFF position activating automatic lamp control (ALC). The LH HDLP and RH HDLP fuse in the fuse block - underhood, supply battery positive voltage to both low and high beam lamps at all times. For manual operation, when the headlamp switch is in the ON position, the headlamp switch supplies ground directly to the headlamps and to the body control module (BCM) on the headlamp low or high beam signal circuit, depending on the position of the headlamp dimmer switch. The BCM uses this signal to determines if the conditions are present to illuminate the daytime running lamps or park lamps.
The headlamp switch of the multifunction switch controls the ground for the body control module (BCM). The BCM monitors the park lamp switch signal. Once the BCM senses a voltage drop on the park lamp switch signal the BCM supplies a ground to the headlamp relay control circuit. The headlamp relay than supplies a ground to the headlamp circuit thus turning on the headlamps. Both the high and low beam headlamp relays are soldered to the underhood fuseblock.
The headlamp may be turned on 2 different ways. First, when the driver places the headlamp switch in the ON position, for manual operation. Second, with the headlamp switch placed in the OFF position activating automatic lamp control (ALC). The Left High Beam, Right High Beam, Left Low Beam, and Right Low Beam fuses in the fuse block - underhood, supply battery positive voltage to both low and high beam lamps at all times. For manual operation, when the headlamp switch is in the ON position, the headlamp switch supplies ground directly to the headlamps and to the body control module (BCM) on the headlamp low or high beam signal circuit, depending on the position of the headlamp dimmer switch. The BCM uses this signal to determines if the conditions are present to illuminate the daytime running lamps or park lamps.
The headlamp may be turned on 2 different ways. First, when the driver places the headlamp switch in the ON position, for manual operation. Second, with the headlamp switch placed in the OFF position activating automatic lamp control (ALC). The Left High Beam, Right High Beam, Left Low Beam, and Right Low Beam fuses in the fuse block - underhood, supply battery positive voltage to both low and high beam lamps at all times. For manual operation, when the headlamp switch is in the ON position, the headlamp switch supplies ground directly to the headlamps and to the body control module (BCM) on the headlamp low or high beam signal circuit, depending on the position of the headlamp dimmer switch. The BCM uses this signal to determines if the conditions are present to illuminate the daytime running lamps or park lamps.
The flash to pass of the headlamp switch supplies a ground to the high beam headlamp circuit when applied. With the ground that is supplied by the flash to pass switch the high beam headlamps will stay ON as long as the switch is toggled.
When the ignition switch is turned to the ON position, the vacuum fluorescent (VF) display, radio, turns ON at maximum brightness. When the park lamps are ON, all incandescent back lighting turn ON at the dimming level indicated by the indicated dimming level. When the headlamp switch is placed in the PARK position, the park lamp supplies voltage circuit provides an input to the body control module (BCM). The BCM then supplies voltage to the I/P dimming switch through the I/P dimming lamps control circuit. The setting of the I/P dimmer switch determines the amount of voltage that the I/P dimming switch supplies to the BCM through the I/P dimming lamps low reference circuit. The BCM than sends a pulse width modulation (PWM) voltage to all the interior lamps. All the VF the incandescent back lighting lamps are provided a specific voltage and are then grounded. When the I/P dimmer switch is moved from MIN to MAX all VF displays, as well as all incandescent back lighting responds from minimum intensity to maximum brightness in response to the I/P dimmer switch.
When the ignition switch is turned to the ON position, the vacuum fluorescent (VF) display, radio, turns ON at maximum brightness. When the park lamps are ON, all incandescent back lighting turn ON at the dimming level indicated by the indicated dimming level. When the headlamp switch is placed in the PARK position, the park lamp supplies voltage circuit provides an input to the body control module (BCM). The BCM then supplies voltage to the I/P dimming switch through the I/P dimming lamps control circuit. The setting of the I/P dimmer switch determines the amount of voltage that the I/P dimming switch supplies to the BCM through the I/P dimming lamps low reference circuit. The BCM than sends a pulse width modulation (PWM) voltage to all the interior lamps. All the VF the incandescent back lighting lamps are provided a specific voltage and are then grounded. When the I/P dimmer switch is moved from MIN to MAX all VF displays, as well as all incandescent back lighting responds from minimum intensity to maximum brightness in response to the I/P dimmer switch.
The body control module (BCM) controls the park lamp relay by grounding the control circuit on the park lamp relay when the headlamp switch is turned to the PARK or the HEAD position. This energizes the park lamp relay, illuminating the park lamps.
The body control module (BCM) controls the park lamp relay to ground the control circuit on the park lamp relay when the headlamp switch portion of the turn signal multifunction switch is turned to the PARK or the HEAD position. This energizes the park lamp relay, illuminating the park lamps. The park lamp relay is directly soldered to the underhood fuseblock circuit board. The replacement of the underhood fuseblock needs to be done to replace the park lamp relay.
When the roof rail reading lamps switches are in the OFF position, the body control module (BCM) supplies the roof rail reading lamps park lamps with voltage and ground. The BCM maintains voltage and ground for a set amount of time for the illuminated entry option. When the roof rail reading lamp switch is in the ON position the BCM only supplies the voltage for the roof rail lamps
The stop lamp switch is supplied voltage by the brake fuse. When the brake pedal is pressed the stop lamp switch closes supplying voltage to the stop lamp light bulbs.
The stop lamp switch is supplied voltage by the brake fuse. When the brake pedal is pressed the stop lamp switch closes supplying voltage to the stop lamp light bulbs.
Voltage runs through the left and right turn signal fuses of the instrument panel I/P fuse block, then through the body control module BCM, before reaching the turn signal multifunction switch. When the turn signal switch is engaged, the switch closes and supplies voltage to the front and rear park/turn signal lamps.
Voltage runs through the left and right turn signal fuses of the instrument panel I/P fuse block, then through the body control module BCM, before reaching the turn signal multifunction switch. When the turn signal switch is engaged, the switch closes and supplies voltage to the front and rear park/turn signal lamps.