Welcome to our resource for MG Car Information.
MG MGF Technical - curious about MFU in the fuse board assy
I've just the red coloured black-box
Rover MFU (multi function unit) Part No YWC104500
in my hands. Dismantled from located behind the fuse board of an old wreck and opened, what else ;)
Two relays inside (NEC bistable + a cheap Malaysia made with one coil/contact), a buzzer, lots of pull-up resistors two ICs ULN2003A a transistor and a Lucas ASCIC PLCC44.
PC board is marked as made 13.97 and type 23VT Lucas.
Has any of you an idea on how to get the internal wiring and function diagrams.
I guess it's not unique made for the MGF but may as well be used at other Rover cars.
Special interest relates to
- Input 15 from the fog light supply wiring loom
What is it good for, does it only provide a signal for the buzzer ?
Silly question, but not only I wondered already about this input, cause it doesn't have any effect on the lights itself.
- Output 4 (green-orange) to the rear screen heater relay
- Input 22 (black-orange) from the rear screen heater switch
Pictures will follow later. I've got a lot of pictures but uploads delay cause of my current desperate tries to get my PC running.
Dohh, the Laptop crashed on friday with a power supply failure.
Not sure about the input 15 from the fog lamp. I presume you mean front fog lamp. Perhaps it latches the front fogs on when you operate the switch. Then when you turn off the ignition and on again the front fogs are now off until you operate the switch again. Hope you understand that.
Input 22 from the heated window switch and input 13 from the oil pressure switch must both be 12 volts so that the output goes to the window element. This prevents you using the heated window when the engine is not running. Hope this helps.
My wiring diagrams do not include the front fog lamp wiring. I cannot find pin 14 on the MFU mentioned anywhere.
thanks for your interest :)
I understand your hints. Front fog lamp, it is.
In former discussiones we assumed as well that this wire from the FFL (front fog lamp) may not be useless. First thoughts on forcing the FFL off when the main beam gets on or anything like that were wrong. I'll take your hint and will try it.
Disconnect the input and see what it does due ignition off/on.
>My wiring diagrams do not include the front fog lamp wiring. I cannot find pin 14 on the MFU mentioned anywhere.
None of the current known schedule versions for MK1 or MY2000 mention anything on this add on. That's the reason for my question for other applications of this MFU :)
>Input 22 from the heated window switch and input 13 from the oil pressure switch must both be 12 volts so that the output goes to the window element. This prevents you using the heated window when the engine is not running. Hope this helps.
Yup, this helps of course and this signal may be of interest as well for other mod applications !!
I measured this afternoon at another MGF on which the HRW heater doesn't work. (HRW is heated rear window)
BTW this is the hardtop from Tony/Utrecht :))
At my car the relay makes 'click' on opening the circuit by pressing the HRW heater switch and also the yellow light in the HRW heater switch comes on. Engine must run of course.
At the chaps car this did not work. We swaped the relays and switches with no result and measured along the wiring. No differences between mine and his car(without the missing voltage at the relais coil)
My thoughts went to any missing connection at the MFU, cause the last works before adding the HRW relay was the front fog lamp installation in any Rover garage.
At last I gave in, pulled out a spare MFU from the wreck and... surprise, surprise it worked.
MFU damageded !! And never read before of a broken MFU at this BBS.
Another surprise for me was that the 'red-box' has no other connection to the fuseboard than the both multi connectors (grey and white coloured).
I took pictures of the good MFU before we installed it.
.. under construction, text will follow.
The damaged one will get to my hands hopefully in next week if the owner hands it over. He'll try to make some own researches himself at first.
From memory (which isn't very good), the input into the MFU from the front fog light is to enable you to have the rear fog on, when only the front side and front fogs are switched on. Otherwise the rear fogs will only switch on with front dipped lights.
|> From memory (which isn't very good), |
Gerald, please don't worry. That is the reason why most of us play around here ;)
The ASIC in the MFU is obviously not the newest design. I suppose it is a very simple design with some 'wired or' and such easy passiv electronic stuff.
So it may of course be right that the 10 or 15 input signals are used only to release or block the affiliated outputs.
I'll try what you mentioned if I find time.
No other voluntate out there for this function tests ?
This thread was discussed between 22/09/2001 and 23/09/2001
MG MGF Technical index
This thread is from the archive. The Live MG MGF Technical BBS is active now.