Ignition Switch and Key
The ignition switch (
) has four positions: AC-
CESSORY, OFF, ON, and START. In addition, the
same key locks and unlocks the cab doors.
In the OFF position, the key slot is vertical; the key
can be inserted and removed only in this position.
The following can be operated in the off position (re-
gardless of whether the key is inserted): The low-
beam headlights, taillights, brake lights, road lights,
dome lights, clearance lights, turn signals, hazard
warning lights, horn, CB radio, power windows, ciga-
rette lighter, clock, and electric oil pan heater.
In the ACCESSORY position, the key is turned coun-
terclockwise. The radio, stereo system, mirror heat,
air dryer, backup lights, and all of the electrical sys-
tems that are operable in the off position are oper-
able in the accessory position.
In the ON position, the key is turned clockwise and
all electrical systems are operable. The low air pres-
sure and low oil pressure warning lights (or mes-
sages) and buzzer operate until the engine is started
and pressure is built up.
Electrical System
The Business Class® M2 features a new type of
electrical system, different from any previous vehicle.
Multiple electrical signals are carried along a simpli-
fied set of wires, reducing the size of wiring bundles.
There are significantly fewer wires overall, meaning
less chance of damage, shorts and other problems.
WARNING
Do not attempt to modify, add, splice, or remove
electrical wiring on this vehicle without authoriza-
tion from Freightliner Engineering. Doing so
could damage the electrical system and result in
a fire that could cause serious personal injury or
property damage.
There are two new electrical modules, a master mod-
ule located near the frontwall (bulkhead module) and
a slave module located between the frame rails
(chassis module).
This new wiring system features intelligent controls
that blink to show switch activity and error conditions.
These controls cannot be distinguished by their ap-
pearance, only by their function.
For more information about these controls, see under
the headings "Axle Switches" and "Suspension
Dump Switch."
Lighting Controls
The lighting controls mentioned under this heading
generally operate through switches located on the
dash.
Two types of dash switches are used:
•
Paddle switches with a single paddle located in
the center of the switch. The paddle can be
raised or lowered to perform a function.
•
Rocker switches that can be pressed at either
the upper or lower end to perform a function.
Certain rocker switches are guarded to prevent
them from being switched on or off acciden-
tally.
When the panel lights are on, most switch legends
are backlit with a colored light, usually green. This
allows the driver to find the switch more easily in the
dark. When the switch is on, the switch icon is nor-
mally backlit with a colored light, usually amber.
Some switch icons are dead-fronted (not visible until
the switch is turned on). When turned on, some
switches are illuminated from within by a red or
amber LED (light-emitting diode).
Control Panels
The left-hand control panel (
) contains a lou-
vered window outlet for the face vents of the heating,
ventilation, and air conditioning system (HVAC), and
four switches arranged in a vertical line, usually the
09/12/2001
f610509
Fig. 4.1, Ignition Switch Positions
Controls
4.1
