Mazda RX-8 2004 Service Highlights page 454

DISCHARGE HEADLIGHT STRUCTURAL VIEW
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DISCHARGE HEADLIGHT OPERATION
1. A high voltage pulse (approx. 25,000 V) traveling from the discharge headlight control unit is applied between
both discharge headlight bulb terminals, energizing the xenon gas in the bulb.
2. Due to the energizing of the xenon gas, the temperature of the discharge headlight bulb interior increases,
vaporizing the mercury and discharging an arc.
3. Due to the mercury and discharging the arc, the temperature of the discharge headlight bulb interior increases
further, metallic iodide is vaporized and separated, and metallic atoms are discharged, producing light.
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DISCHARGE HEADLIGHT CONTROL MODULE FUNCTION
• Controls the amount of electrical current while the discharge headlights are on to maintain optimum brightness
together with lighting stability.
• The failure detection functions are as follows:
— Abnormal input detection function
— Abnormal output detection function
Abnormal Input Detection Function
• If the discharge headlight control module input voltage (9—16 V) fails to maintain operational voltage (except
for the drop in voltage immediately after the headlights are turned on), the discharge headlight control module
turns off the headlights for protection and to prevent partial operation.
• The discharge headlight control module turns the headlights back on at resumption of normal operational
voltage.
Abnormal Output Detection Function
• If there is an abnormality in the output system (detects an open or GND short circuit in harness), the discharge
headlight control module turns off the headlights for protection and to prevent partial operation errors.
• If the discharge headlight control module turns off the headlights due to an abnormality in the output system,
the discharge headlight control module will maintain them in the off condition until the light switch is turned
again from off to on.
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09–18–4
LIGHTING SYSTEMS
A
A A
METALLIC ATOMS
DISCHARGE HEADLIGHT BULB
LIGHT
TERMINAL
LIGHT
METALLIC IODIDE MERCURY
DISCHARGE
HEADLIGHT BULB
DISCHARGE
CONTROL MODULE
SEC. A—A
XENON GAS
DISCHARGE
B+
HEADLIGHT
CONTROL MODULE
TERMINAL
CHU091801052S02
HEADLIGHT
CHU0918S132
CHU091801052S03
CHU0918S128
CHU091801052S04