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2016 – MX-5 – i-ACTIVSENSE

HIGH BEAM CONTROL (HBC) SYSTEM

Outline

• The high beam control (HBC) system turns the headlights HI off when the forward sensing camera (FSC) installed to the windshield recognizes a vehicle ahead and when traveling through towns and cities while the vehicle is being driven with the headlights HI turned on. As a result, driver visibility is assured while preventing blinding of other vehicles from headlight glare.

CAUTION:

• Under the following conditions, the ability of the forward sensing camera (FSC) to detect light-emitting objects decreases, which could result in the system not operating normally and the inability to detect vehicles ahead.

• Brightness of moonlight in surrounding area

• Poor visibility due to rain and fog

• Scratches or dirt on the camera lens or windshield glass

• Do not rely solely on the high beam control (HBC) system, and perform the appropriate switching operation based on a visual determination of the conditions.

• If the forward sensing camera (FSC) aiming is not completed correctly, the forward sensing camera (FSC) cannot record the camera shooting angle and the high beam control (HBC) system may not operate normally. When performing the following servicing, always perform the forward sensing camera (FSC) aiming. In addition, for the forward sensing camera (FSC) aiming procedure, refer to the [FORWARD SENSING CAMERA (FSC) AIMING] in the Workshop Manual.

• Forward sensing camera (FSC) replacement

• Forward sensing camera (FSC) clip replacement

• Windshield replacement

Functions

• If the forward sensing camera (FSC) recognizes light-emitting objects (vehicles ahead, street lights (driving in city/town)) in front of the vehicle using the light-emitting object detection function while the vehicle is traveling with the headlights HI turned on, it turns off the headlights HI and turns the headlights HI on when light-emitting objects are no longer detected.

• For the light-emitting object detection function of the forward sensing camera (FSC), refer to the [FORWARD SENSING CAMERA (FSC)]. (See FORWARD SENSING CAMERA (FSC).)

Setting function for control order of precedence

• If several light-emitting objects are recognized (vehicles ahead, street lights (driving in city/town)), control is conducted according to the following order of precedence.

• Closest on-coming vehicle

• Closest vehicle ahead (no on-coming vehicles)

• Street lights (driving in city/town)

System conditions display function

• The forward sensing camera (FSC) displays the system status using the HBC indicator light (green) and HBC warning light (amber) in the instrument cluster, and the warning display (with center display) on the center display.

Condition		HBC indicator light (green)	HBC warning light (amber)	Center display
Light switch is in AUTO and dimmer switch is in position other than HI		Off	Off	No display
Headlights off
While vehicle is stopped
System set to off by personalization
Light switch is in AUTO and dimmer switch is in HI and headlights turned on		On	Off	No display
Forward sensing camera (FSC) detects camera fogging		Off	On	Warning display*1
Forward sensing camera (FSC) detects that the camera is dirty
Malfunction in high beam control (HBC) occurs
Forward sensing camera (FSC) has a malfunction

^*1

For the warning display content on the center display, refer to the [CENTER DISPLAY]. (See CENTER DISPLAY [WITH CENTER DISPLAY].)

Structural View

System Wiring Diagram

Block Diagram

Operation

Low beam switching operation

• When any of the following conditions is met while the headlights are turned on with the light switch in the AUTO position and the dimmer switch in the HI position, the headlights HI turns off.

Operation condition

• Vehicles ahead, street lights (driving in city/town) are recognized

• Vehicle speed is 20 km/h {12 mph} or less (vehicle speed signal of 20 km/h {12 mph} or less is received)

• When any of the operation conditions is met, the forward sensing camera (FSC) sends (1) a headlight HI off request signal to the BCM via CAN communication.

• When the BCM receives the headlight HI off request signal, it sends (2) the headlight HI off request signal to the electrical supply unit (ESU) via LIN communication.

• When the electrical supply unit (ESU) receives the headlight HI off request signal, it turns the headlights HI off (3).

High beam return operation

• When the following condition is met, the headlights HI turn on.

Operation condition

• Vehicle speed is 30 km/h {19 mph} or more (vehicle signal of 30 km/h {19 mph} or more is received) and vehicles ahead or street lights (driving in city/town) are not recognized

On-coming vehicles

• When the forward sensing camera (FSC) determines that a recognized on-coming vehicle moves away from the camera range, it sends (1) a headlight HI on request signal to the BCM via CAN communication.

• When the BCM receives the headlight HI on request signal, it sends (2) the headlight HI on request signal to the electrical supply unit (ESU) via LIN communication.

• When the electrical supply unit (ESU) receives the headlight HI on request signal, it turns the headlights HI on (3).

Vehicles ahead or street lights (driving in city/town)

• If the forward sensing camera (FSC) no longer detects a recognized vehicle ahead or street lights (driving in city/town) in the camera range, it maintains (1) the headlights LO on condition for a certain period of time.

• If the forward sensing camera (FSC) does not detect vehicles ahead or street lights (driving in city/town) after the certain period of time has elapsed, it sends (2) a headlight HI on request signal to the BCM via CAN communication.

• When the BCM receives the headlight HI on request signal, it sends (3) the headlight HI on request signal to the electrical supply unit (ESU) via LIN communication.

• When the electrical supply unit (ESU) receives the headlight HI on request signal, it turns the headlights HI on (4).

Forward sensing camera (FSC) loses sight of vehicle ahead which is cornering

• If the forward sensing camera (FSC) loses sight of a recognized vehicle which is cornering, the forward sensing camera (FSC) maintains the headlights LO on condition until reaching the locus at which the forward sensing camera (FSC) lost sight of it.

• If the vehicle ahead is not detected at the locus at which the forward sensing camera (FSC) had lost sight of it, the headlights HI are turned on. If the vehicle ahead is detected, the headlights LO on condition is maintained.

Forward sensing camera (FSC) suddenly loses sight of light-emitting object within camera range (vehicles ahead, town/city streets (street lights))

• If the forward sensing camera (FSC) suddenly loses sight of a recognized light-emitting object in the camera range, the headlights LO on condition is maintained for a certain period of time.

• Depending on whether a light-emitting object is detected or not after the certain period of time has elapsed, the system determines that the headlights HI are to be turned on.

Fail-safe

• If a malfunction is detected in the system, control is inhibited and the headlights HI are turned on.

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