What locks the centre dif - the solenoid or the motor on the gearbox?

from the WSM:

Quote:

The DD295 transfer case is full time, permanent four-wheel-drive unit, with 50/50 torque distribution to the front and rear driveshafts. The transfer case is identical for all engine derivatives and supports the following features:
Permanent four-wheel-drive with a bevel gear center differential, providing a 50:50 torque split
Selectable high and low range for optimum on-road and off-road performance
a pre-loading function, increasing locking torque with increased driving torque
a slip controller to increase locking torque under off-road conditions and decrease locking torque for optimum
comfort, e.g. parking. The unit is located under the vehicle and is mounted on the cross-member, behind the transmission.

The input torque is equally distributed via a bevel gear type differential. In order to provide an optimal torque distribution to each wheel in all driving conditions, the transfer case is equipped with an electronically controlled locking and torque-biasing device. This device detects wheel slip via various vehicle system inputs to the Transfer Case Control Module (TCCM) and locks the differential accordingly. The locking torque is applied through a multi-plate clutch assembly.

A planetary gear set, located in the differential assembly, allows the driver to select high or low range. When in low range, the planetary gear set provides a ratio of 2.93:1, which gives the vehicle an extremely low crawl speed for off road driving and trailer towing. High range is a direct drive from the transmission output shaft and provides a 1:1 ratio. The oil used in the transfer case is specially developed and contains unique additives, which enhance the transfer case operation. No other oil must be used in the transfer case. A unique type of grease, Weicon anti-seize montagepaste grau TL 7391, must be applied to the transfer case input shaft spline when installing the transfer case.

Transfer Case Motor
One motor operates both the high/low range change and the differential locking and torque-biasing device (multi-plate clutch). The motor solenoid switches between the 2 functions, while the motor provides the rotational movement for both operations.

The transfer case motor provides the necessary movement to perform the high/low range change and the multiplate clutch actuation. The motor is located on the rear casing assembly and secured with four bolts. The motor is a PWM controlled, DC motor with an integrated worm gear reduction drive. It is connected to the TCCM with an 8-pin connector; the power supply of the motor is maintained through 2 large diameter cables on the motor connector. An internal position sensor checks the rotational movement of the motor. There is a temperature sensor located within the motor housing. the sensor is connected to the TCCM.

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2010 Defender Puma 90 + BAS remap + Alive IC + Slickshift + Ashcroft ATB rear
2015 Range Rover Sport Supercharged V8 HSE Dynamic



Defender Puma Workshop Manual: https://bit.ly/2zZ1en9
Discovery 4 Workshop Manual: https://bit.ly/2zXrtKO
Range Rover/Sport L320/L322/L494 Workshop Manual: https://bit.ly/2zc58JQ

Thanks for that - its actually very helpfull. I think i have a defective transfer solenoid (what my GAP tool suggests) and your description suggests the solenoid operated the dif lock (need to re read again.)

I can get it to switch ranges but not always as it turns functions off.

Thanks

Spencer

ah, sorry, this is for the L494, not sure about the L320.

You can access the workshop manual for the L320 via the link in my signature  --
2010 Defender Puma 90 + BAS remap + Alive IC + Slickshift + Ashcroft ATB rear
2015 Range Rover Sport Supercharged V8 HSE Dynamic



Defender Puma Workshop Manual: https://bit.ly/2zZ1en9
Discovery 4 Workshop Manual: https://bit.ly/2zXrtKO
Range Rover/Sport L320/L322/L494 Workshop Manual: https://bit.ly/2zc58JQ

The diff is locked by the motor. The motor also changes the range. The solenoid switches the motor between the two functions. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed