A search of this forum and others reveals that this is a common issue, but is reported with slightly different symptoms. There also does not seem to be a firm resolution for the problem. Several folks seem to give up and work around the issue.

Recently I climbed in my '97 D1 and when I tried to start it, the battery was dead. A quick jump, and she was up and running, tested the battery and charging system and all was well. I started hunting around and noticed all three interior lights were on and stayed on even after shutting down the engine and locking the car via remote. There is usually an 8 minute fail safe timer where the lights get shut off regardless of the status of the doors, and that failed to shut them down. That 8 minute timer had been working fine the day before.

A quick visual check of the door switches seemed to indicate they were good. Next I go rooting around in the fuse box for the dome light fuse, and of course it's not that simple 'cause there isn't one. I do discover pretty quickly that pulling fuse 12 labeled Multi Function Unit in the primary fuse box under the dash, shuts them off. Reinstalling the fuse and they turn on again. Pulling it again, however failed to shut the lights off. Curious. I find I must now pull fuse #1 in the first aux. fuse box labeled Anti Theft Alarm as well as fuse #12. But even that doesn't shut them off completely, it simply makes them go really dim.

I work around the issue like others before me by manually flipping the switch for the light up front, and removing the bulbs from back seat and cargo areas. Because the behavior is oddly intermittent, I am guessing the delay for the dome light is in the MFU and it has gone bad. There could be a short elsewhere, but that's my guess. Anyone agree or disagree?

 

sounds like it. Did you check all the fuses? these things are weird when it comes to electrical gremlins.

 

Pulled every single fuse and checked it. Not that that means anything.

What makes me believe it's the MFU is that the timed shut off does not work, nor does the fail safe. Also that two completely different circuits, both regulated by the MFU, are involved. And finally that even pulling both fuses there is still some current running through the lights.

I am interested in entering the diagnostic mode of the MFU as detailed in the RAVE manual, and seeing what happens. I assume there is no reset/reboot for this thing, it either works or it doesn't? Also, from the schematic, the MFU seems to be attached to the back of the fuse box itself. Correct?

Can't say I like the price of the MFU at $200.00 either, but I'm always leery of buying electronics used.

 

Is there a dealer near you? They can reprogram it for less than buying a used one I am going to guess.

 

Are you saying you know for a fact it is possible to reprogram the MFU, and that the cost may be less than replacing it, or are you guessing it can it can be reprogrammed?

It has been my experience that the local Rover dealer is obscenely expensive for everything. $850.00 to R&R the alternator???!!! They have not been an option since my D1 went out of warranty 10 years ago.

 

Considering that a DI alt is $700 new $850 to R&R it is not that bad all things considered.

No I do not know if the MFU can be reprogrammed or not.
There maybe a crack in the circuit board or it may just be totally bust.
Maybe it can be programmed. If so I can't imagine it would take more then a hour.
A hours labor rate is still cheaper than a used one.
Just a thought.
Maybe a phone call is in order.

 

These things are weird period. But wife loves it.