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7
CONNECTING THE DOME LIGHTS
The dome lights in the video monitor require three connections to the vehicle's wiring. There are two common
types of dome light circuits used, positive or negative switched. Positive systems supply voltage to the interior
lights to turn them on, negative switched systems apply ground to illuminate the bulbs. To determine which system
you have you must locate the wires at the dome light. On a positive switched system, with all the doors closed and
the lights out, both wires at the dome light will rest at ground. When the light is activated, one of these wires will
switch to +12 vdc. This is the vehicle's switching wire. On a negative switched system, with all the doors closed
and the lights out, both wires at the dome light will rest at + 12vdc. When the light is activated, one of these wires
will switch to ground. This is the switching wire.
For positive systems, connect the purple / brown (Lamp auto) wire to the vehicle's switched wire. Then connect
the red / black (lamp on) wire to a fused constant 12 volt source and the black / red (lamp common) wire to a good
ground. Positive systems are commonly found on Ford vehicles.
For negative systems, connect the purple / brown (Lamp auto) wire to the vehicle's switched wire. Then connect
the red / black (lamp on) wire to a good ground and the black / red (lamp common) wire to fused constant 12 volt
source. Negative systems are commonly found on General Motors and import vehicles.
Note: Some vehicles which incorporate transistorized control of the dome light circuit, such as the 1999 Dodge
Caravan, may require that the purple / brown (Lamp auto) wire be connected to the door pin switch wire, as the
additional current draw of the Monitor's lights may not be supported by the output of the vehicles body control
computer.
Positive Switched Dome Lighting
Red / black - Lamp on
Factory Dome light circuit
To 12 pin
connector
on Monitor
To
constant
+12vdc
To
constant
+12vdc
Black / red - Lamp common
Purple / brown - Lamp Auto
Factory Door ajar
switch or Body
Control computer