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 switched systems or negative switched systems.
Positive switched systems supply voltage to the interior lights to turn on; negative switched systems apply
ground to illuminate the bulbs.
To determine which system you have to 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 +12 VDC. When the light is activated, one of these wires will switch to ground. This is the vehicle’s
switching wire.
For positive switched 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 switched systems are commonly found on Ford vehicles.
For negative switched 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 a fused constant 12 volt source. Negative switched systems are commonly found on General
Motors and import vehicles.
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
vehicle’s body control computer.
Note:
Positive Switched Dome Lighting
Red / black - Lamp On
Factory Dome Light Circuit
To 3 pin
connector
on Monitor
To
constant
+12 VDC
To
constant
+12 VDC
Black / red - Lamp Common
Purple / brown - Lamp Auto
Factory Door Ajar
Switch or Body
Control Computer
11
Fused
