Differential Lock Switch
Notice: The differential lock should only be engaged when the vehicle is stopped or moving slowly at low throttle. This will prevent internal axle damage.
A two-position guarded rocker switch controls the differential lock. See Fig.. To lock the wheels together, momentarily press the upper half of the switch. To unlock the wheels, press the upper half of the switch again.
Fig. 1, Differential Lock Switch, Optional
Important: The differential lock rocker switch is guarded to prevent unintentional switch activation. If the light emitting diode (LED) in the switch begins to blink during normal operation, when the switch has not been activated, an error condition exists. Bring the vehicle to an authorized Freightliner service facility as soon as possible.
When the differential lock switch is pressed, three responses are possible: a normal response, a slow response, and an abnormal response.
Normal Response: The LED in the switch blinks until the axle has responded to the request to lock the wheels. At this point, the LED remains illuminated constantly. In normal operation, the wheels may lock so quickly that the blinking of the switch is barely noticeable.
If operation of the switch 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.
Slow Response: If operation of the switch is slowed for any reason (vehicle moving too fast, low air pressure, etc.), the switch will continue to blink until the wheels are able to lock. As in the normal response, the LED remains illuminated when the differential lock is engaged.
Note: If the vehicle is moving too fast, let up slightly on the accelerator. As the vehicle slows, the wheels will lock.
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.