Switch: Description and Operation

GF54.25-P-4311G Differential Locks Switch Group, Component Description
MODEL 463.306 /336 /346 up to 31.5.12 as of Model Year 2011 /YoM 10
MODEL 463.202 /222 /236 /237 /270 /271 /303 /340 /341 up to 31.5.12 as of Model Year 2009 /YoM 08





S76 Differential lock switch group
S76/2 Differential lock switch (longitudinal equalization)
S76/3 Rear axle differential lock switch
S76/4 Front axle differential lock switch

Location
The differential locks switch group is located centrally in the instrument panel.

Task
The driver can switch the following differential locks on or off via the differential locks switch group:
- Differential lock for transfer case longitudinal equalization
- Rear axle differential lock
- Front axle differential lock
The differential locks can only be engaged in this sequence.
Disengaging takes place in the reverse order.

Function
The differential lock switch, longitudinal equalization, rear axle differential lock switch, front axle differential lock switch has an engagement indicator (yellow) and a function indicator lamp (red) in each case. Once the switch for the desired differential lock is operated the corresponding engagement indicator lamp lights up.
For vehicles up to 31.8.10 the engagement indicator in the differential lock, longitudinal equalization switch is switched on irrespective of the transfer case switch position
For vehicles as of 1.9.10 this engagement indicator is only switched on when the transfer case is shifted to "Low Range".
The engagement indicators in the differential lock, rear axle switch and in the differential lock, front axle switch light up when the shift operation in each differential has taken place.
As soon as the longitudinal equalization start-up check (transfer case) has been activated, the differential locks switch group transmits the signal "Lock programmed" to the ESP control unit (N30/4) (without code (ZS6) Special protection version FB6 and without code (ZS7) Special protection version FB7) or to the ABS control unit (N47-7) (with model 463.236 with code (ZS6) Special protection version FB6 or with code (ZS7) Special protection version FB7).
The ESP control unit immediately deactivates all control functions of the Electronic Stability Program (ESP) except for the control of the antilock brake system (ABS) and electronic brake force distribution (EBV). When the mechanical shift operation of the differential lock is completed and the red indicator lamp in the differential locks lights up, the signal "Lock active" is transmitted from the differential locks switch group to the ESP control unit or ABS control unit. Thereupon the ESP control unit or the ABS control unit deactivates the ABS control.
The following indicator lamps are actuated in the instrument cluster (A1):
- ESP OFF indicator lamp (A1e30) (as of 1.9.10 without code (ZS6) Special protection version FB6 and without code (ZS7) Special protection version FB7)
- ESP warning lamp (A1e41) (up to 31.8.10 without code (ZS6) Special protection version FB6 and without code (ZS7) Special protection version FB7)
- ABS indicator lamp (A1e17)
In addition the corresponding text messages are displayed in the multifunction display (A1p13). These displays in the instrument cluster are only switched off when all function indicator lamps in the differential locks switch group are switched off and a "stable driving condition" is retained for at least t = 3 s (no control needed in any form).
When the rear axle differential lock is disengaged the front axle differential lock is disengaged automatically at the same time.
When the transfer case differential lock is disengaged all the differential locks are disengaged automatically at the same time.