Service manual

91
The door pin switches control the Courtesy Light output. This output will be on, when
the doors are opened and for 12 seconds after they are closed. This output is intended
to be used to feed lights such as step well lights that can only be turned on by the
doors being opened or the headlight switch mounted courtesy light switch. Light circuits
1 and 2 also are controlled by the door pin switches and these lights will also be on
when the courtesy lights are on. If the doors are left open, the lights will automatically
go out in twenty minutes. To turn them on again, all the doors must be closed and re-
opened.
All the switch panels operate from a common, three-wire cable. These wires are used
for back lighting, ground, and signal. The Smart Fuse Block Plus switches loads by
monitoring the voltage on the signal wire. A resistor in the Block is used to pull the sig-
nal line high. The switch panels have various values of resistors associated with each
function. When one of the switches is pressed, the voltage on the signal wire is
dropped to a level that corresponds to that function. Circuitry in the Block senses the
voltage and switches that function on or off.
Battery and Ignition Circuits
The Battery and Ignition circuits are not controlled by the Smart Fuse Block Plus.
Power to these outputs is brought into the fuse block from the OEM wiring and is fused
on the block in a normal fashion.
The Battery fuses are used for circuits that feed intermittent or uninterruptible loads,
such as power sofa and 12 volt outlet, which may be used to supply a 12-volt cooler.
The ignition fuses are used for circuits that feed loads that should operate only when
the ignition is turned on, such as the rear fan.
Switched Outputs
The four Switched Outputs are each switched by a relay in the block. Each of these cir-
cuits is operated by the push button switches and turned off when the ignition goes off
and by a 20-minute timer. An opening of a door or ignition resets this timer. The ignition
holds the timer in reset, so these outputs will stay on all the time the ignition is on.
These outputs will all be shut off when the ignition is turned off. If they are turned on
after the ignition is turned off, they remain on for 20 minutes.
The timer has 2 speeds, which are dependent on the incoming battery voltage. If the
battery is higher than 12.1 volts, the clock runs at its normal speed. If the battery drops
below 12.1 volts, the clock speeds up approximately 10 times so the timer will shut off
in about 2 minutes instead of the normal 20 minutes.
Courtesy Lights
When the doors are opened, Courtesy Lights, Lights 1, and Lights 2 circuits are turned
on. This function is operated by a timer that keeps the lights on while the doors are
opened and for up to 12 seconds after they are closed. If the ignition is turned on dur-
ing this 12 seconds, the Courtesy Lights go out immediately.