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MG MGF Technical - Blown Fuse - No Interior Lights

I have had rather a strange problem recently. I have just had a new windscreen and new bootlid for my 99 MGF.

On Friday i attempted to dead lock the car and noticed that i could not. Had a look at the fuse box in the passenger compartment and noticed fuse 12 blown. This is the fuse that is used to isolate the Interior lights and ICE. Whent to replace fuse with the correct 15 amp one and it blew straight away. whent back to my dealer that carried out the work. They attempted to put a fuse into the fuse box and hey presto everything seemed fine. Interior ligths on under the rear view mirror and stereo all functioning. Whent home last night in the dark and realised that i have no passenger footwell light when i open the door, no under bonnet light, no light around igniton switch. I did notice that the light under the boot lid is working though and also the rear view mirror light when you use the toggle switch under it to turn the ligts on. Any ideas as i am now pulling my hair out !!!!!
P G Olney

Yes,
the wire is purple, it runs all over the car to supply power to the lights and is 'always on' (unless as you know you blow the fuse!).
The problem area is on the wireing loom as it goes into the bootlid, the wires tend to rub here and the purple one rubs thru, shorting and blowing the fuse.

Will
Will Munns

Right, i see will thanks. That sorts out the problem with the fuses, but what about only some of the lights being on. I.e The fuse at the moment is still intact but the footwell lights are not working. Are you suggesting that somewhere in the boot area the purple wire has broken which sends electrical charge to the footwell lights, ignition illumination and front bonnet light.
Paul

I had this recently and it transpired that the original short blew two bulbs as well - so check the bulbs.

Ted
Ted Newman

Oh no, the dealer replace the fuse and the car (stationary) worked correctly untill some flex in the body, a bump in the road, or you opening the boot caused the fuse to go again. Check the fuse carefully it might not seem broken, but you can bet your bottom euro it is.

Will
Will Munns

Will, i have had a look at the fuse and all seems OK. the stereo is working and the rear view mirror works when you use the manual toggle switches. The fuse the oriignally blew was Fuse 12. Do the other lights i.e footwell light and under bonnet light work of a different fuse ?
paul

http://www.mgfcar.de/schedules/sb4.jpg (W [or p] on LHS)
http://www.mgfcar.de/schedules/sb3.jpg (W [or p] on RHS)

Yes fuse 12.
The ICE should still work, but the memory should be wiped every time you switch off the car, and the clock should be stopped.

Will
Will Munns

Paul

Quite a common type of problem. I've just fixed mine. See "fuse problems" in this section about a screen scroll down.

HTH
JohnP

Paul,

It certainly seems a strange problem in that some lights work and some don't although they are on the same fuse.

I would check this scenario:-

Under bonnet lamp not working due to faulty switch or bulb. The switch is subjected to lots of rain water and thus is prone to bad connections.

Footwell lamps not working due to problem with either Multifunction Unit or door switches. The Multifunction Unit (MFU) earths the footwell lamps, the mirror lamps and the glowring around the ignition switch. The MFU enables the system to gradually dim these lights. The door switches control the MFU. If a door switch,boot switch or bonnet switch is left on, the alarm system will not superlock. It assumes a door may be partly open.

The Fuse 12 originally blew because of faulty wiring loom around the bonnet hinge area, or, a problem with one of the previously mentioned circuits such as bonnet lamp, door lamps etc.

and may the Lord have mercy on your soul!


HTH

Bruce

Bruce Caldwell

> The switch is subjected to lots of rain water and thus is prone to bad connections.
This switch is also prone to being disconnected by the garage, mainly due to setting the alarm off with their heads under the bonnet, the switch is quite obvious at the rear left of the bonnet bay, the wire is quite obvious if it is connected or not.

Will
Will Munns

Chaps,

paul

Chaps, just had a look at the bonnet switch, gave it a wiggle and hey presto the light is on. Can you please tell me where the door switches are located. Can you also tell mw what the MFU is, is this part of the ECU.
Paul

Paul,
do the lights work properly from the passanger door?

Will
Will Munns

Will, no they do not. When i open either the passenger door or the drivers door the light do not work.
paul

By the way , where is the MFU located !
grahm

MFU is located under the dash up behind the fuses on driver's side. Mine is red in colour. It controls several functions (hence the name!).

Bruce
Bruce Caldwell

Check dealers used correct fuse, and not a nail. Wouldn't be the first time...

Leigh
L Reid

Paul,

Forgot to answer your other question. The door switches are part of the actual door lock mechanism. There is a switch to indicate that the door is open (interior lights and alarm) and another switch to indicate that the door is locked. Two separate functions. In the RH door the wire Purple/Slate is earthed when the door is ajar. In the LH door it's Purple/White that gets earthed. Problems have often occurred in the past with water ingress into the microswitches and the connectors in the locks.

Bruce
Bruce Caldwell

Thanks for all your help guys. I went home last night and stripped down all the interior around the rear view mirror, no signs of damaged wiring etc. I also checked out the boot area, and again could see no damage. I will have to wait until friday until my F' goes on test book. I can only think it is faulty dorr switches ( a bi strange as when i open both doors the lights do not come on) or a fault MFU. Will keep you informed. Once again many thnaks for taking the time to help, its most appreciated !
paul

This thread was discussed between 01/10/2002 and 02/10/2002

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