Differential Lock Switch
For the differential lock switch on a vehicle with a single drive axle. See Fig..
Fig. 1, Differential Lock on Single Drive Axle
For a vehicle with tandem axles, there are several differential lock options available:
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one switch to control the differential lock on only one of the drive axles (this switch will show only one dot on one drive axle, varying slightly from the switch shown in Fig.).
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one switch to control the differential locks on both drive axles (see Fig.).
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two switches, each of which controls the differential lock on one drive axle.
Fig. 2, Differential Lock on Both Axles
When the differential lock switch is pressed, three responses are possible:
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Normal Response: The LED in the switch blinks until the differential lock is engaged. At this point, the LED illuminates steadily. In normal operation, the wheels may lock so quickly that the blinking of the LED is barely noticeable.
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If engagement of the differential lock mechanism is not possible for any reason (ignition is turned off, vehicle is moving faster than 25 mph, etc.), the LED will stop blinking and turn off.
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Slow Response: If engagement of the differential lock mechanism is slowed for any reason (vehicle moving too fast, low air pressure, etc.), the LED will continue to blink until the wheels are able to lock. As in the normal response, the LED illuminates steadily once the wheels have locked.
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Abnormal Response: If the LED blinks for more than 30 seconds, the lock mechanism may not be fully engaged/disengaged. Bring the vehicle to an authorized Freightliner service facility for testing.