Ignition Switch

The ignition switch has four positions: OFF, ACC (accessory), ON, and START. See Fig.. The ignition key also locks and unlocks the cab doors, baggage door(s), and if equipped, the bunk door(s).

In the OFF position, the ignition switch is vertical. The key can be inserted and removed only in the OFF position.

The following functions are operable when the ignition switch is in the OFF position (regardless of whether the key is inserted):

• low-beam headlights

• taillights

• brake lights

• road lights

• dome lights

• clearance lights

• hazard warning lights

• turn signals

• utility lights

• baggage compartment lights

• spotlights

• horn

• clock

• refrigerator

• CB radio

• power mirrors

• power receptacle

• fuel heater

• electric oil pan heater

• electric or diesel-fired engine coolant pre-heater

Turn the key counterclockwise to reach the ACC position. In addition to all the functions that are operable in the OFF position, the following functions are operable when the switch is in the ACC position:

• radio/stereo system

• heater and A/C fan

• mirror defog

• windshield fan

• ether start system

• air dryer

• backup lights

Turn the key clockwise past the OFF position to reach the ON position. When the ignition is turned on, the following actions should occur:

• electronic gauges complete a full sweep of their dials

• warning and indicator lamps illuminate, then are extinguished

• audible alert sounds for approximately four seconds or until sufficient air pressure builds up in the primary and secondary air systems

• software revision level of the ICU is displayed on the driver message center, followed by any active faults

Turn the key clockwise past the ON position to reach the START position to start the engine. Release the key the moment the engine starts. Do not operate the starter longer than thirty seconds, then allow the starter to cool between attempts. If the starter overheats, the starter protection system will prevent operation of the starter until it has cooled. Release the key the moment the engine starts.