Defender 90 (LD) V8-4.0L (1997)
Body Control Module: Description and Operation
Multi-Function Unit - Self-Test
The multi-function unit is located at the rear of the in-car fuse box on the 1995 Classic and on all Discoverys. It's purpose is to operate/control a number
of vehicle functions and eliminates the need for multiple individual control units.
Input tests:
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Switch ignition "off"
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Press and hold rear defrost switch then switch on ignition (position 2)-release defroster switch (Note: Release the defroster switch within one
second of turning on ignition).
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A series of beeps indicates that the MFU is in diagnostic mode.
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Perform input checks by operating the following switches/controls. A correct input is indicated with a two beep tone.
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Windshield defrost (Classic only)
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Rear window defrost
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Open and close doors and tailgate
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Operate parking/headlamps switch
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Wiper switch in intermittent position
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Windshield/headlamps wash switch
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Rear wiper switch
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Drivers seat belt latch
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Rear fog lamp switch ('97 Discovery only)
Output Tests:
With the system still in diagnostic mode, press and release the rear defroster switch again - now the MFU will provide output signals to the components
which will then operate
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Rear window defroster and dash indicator lamps
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Interior lamp
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Headlamp wash (not Defender)
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Front and rear wipers
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Chime and seat belt indicator lamps
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Rear fog lamps ('97 Discovery)
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Windshield heater ('95 Classic)