Mazda CX-9 2007 Service Highlights page 471

DISCHARGE HEADLIGHT STRUCTURAL VIEW
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DISCHARGE HEADLIGHT OPERATION
1. A high voltage pulse (alternating current approx.
25,000 V) traveling from the discharge headlight
control module 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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LIGHTING SYSTEMS
A
A
DISCHARGE HEADLIGHT BULB
DISCHARGE HEADLIGHT
CONTROL MODULE
SEC. A—A
METALLIC ATOMS
LIGHT
TERMINAL
LIGHT
METALLIC IODIDE
id091800103700
FRONT COMBINATION
LIGHT
ac9uun00000092
id091800103500
DISCHARGE HEADLIGHT BULB
XENON GAS
DISCHARGE
HEADLIGHT
CONTROL MODULE
MERCURY TERMINAL
acxuun00000559
id091800103400
09-18–5
B+
09-18