Which Fuse/Relay?

I have the Haynes manual and have checked everything that i can see might be causing the problem, and it all checks out. So why wont my electrics work?

Neither of my cabin lights work, my heater control light doesnt work, my glovebox light doesnt work. and my boot courtesy lamp doesnt work. They might be unrelated circuits but as i say, all the fuses check out fine. Is there a relay that might have gone somewhere?

Hi,A year of car and model would help but here is my answer: Does everything else work ? Ie: Rear wiper,rear fogs,heated rear window,intermittent front wipers because if they don't it's the MFU which is located on the back of the fuse box as this controls all this and interior lights but not your heater bulb. Are you sure the bulb has not blown in the heater controls ?

Sorry mate, i need to get a sig lol... Its a 1996 300Tdi

Rear wiper doesnt work, intermittent wipers do work. Will have to check heated window and fog lights.

I took the heater control apart yesterday and replaced bulb, it was blown but still doesnt work.

My clock doesnt work either, but i think thats just a replacement job

Any luck with seeing if your HRW and your rear fog lights work ?

yeah theyre both fine, sorry for late update. i checked them hours ago! lol

The three interior lights are one circuit with two fuses one of which is a fusable link, if the lights don't light manually then check the fuses again.
The glove box light is on the same circuit as the R/H front sidelamp so if that still works then you know the fuse is ok so that leaves the switch and the fuse.
If you look at the wiring diagram 18 and 19 in the Haynes it explains the circuits and you will see the common connection for your dash lamps is the lighting switch.

TDIDISCO said:

Hi,A year of car and model would help but here is my answer: Does everything else work ? Ie: Rear wiper,rear fogs,heated rear window,intermittent front wipers because if they don't it's the MFU which is located on the back of the fuse box as this controls all this and interior lights but not your heater bulb. Are you sure the bulb has not blown in the heater controls ?

Click to expand...

Brilliant

Those are the exact symtoms my 'blessed chariot' is suffering with.

So, how and where do I get an MFU from and is it expensive ?

Hi,

There's a multifunction unit mounted on the back of the fuse board below the steering wheel, the buzzer is located in there.
The unit controls things like intermitant wiper delay, interior light fade, rear wiper, etc. I don't know there are any fuses for that circuit, unfortunatley the unit is pretty much non repairable (i'm from an electronics background and I couldn't be bothered), if you do need to replace it I think they are about £97.00...

There is a test mode as described on the rave cd:
(same year as yours so should work)

The multi–function unit (MFU) is mounted on the
rear of the passenger compartment fusebox and has
an input to operation of the following:

Heated rear screen

Heated front screen

Courtesy lights

Side and headlights

Rear fog guard lamps

Headlamp power wash

Front wipers

Rear wash/wipe
Diagnostic Procedure
1. Close all doors and the tailgate.
NOTE: If the oil pressure switch goes open circuit
(engine is started) during the following procedure,
the MFU will exit the diagnostic mode immediately.
2. Press and hold the heated rear screen switch
and switch on the ignition.
3. Release the heated rear screen switch within 2
seconds and the MFU will beep to indicate that it’s in
diagnostic mode 1.
4. Press the heated rear screen switch; the MFU
will beep twice. In turn, operate each of the following
switches, heated front screen, rear fog guard lamps,
side lights, headlights, front wiper and rear wiper.
The MFU will beep twice each time a switch is oper-ated.
5. Pressing the heated rear screen again will cause
the MFU to enter diagnostic mode 2.
6. The MFU will provide outputs to the following in
order given below:

Heated rear screen relay energised for 2 seconds

Heated front screen energised for 2 seconds

Courtesy lights energised for 2 seconds

Dim dip relay energised for 2 seconds

Rear fog guard lamp energised for 2 seconds

Headlamp power wash energised for half a second

Front wiper energised for half a second

Rear wipe/wash energised for half a second
7. The MFU will then exit the diagnostic mode.


Hope this is of some help, if you need it I can send you a copy of the cd so you can trace the wiring diagrams.

PS. After two days trying to fix my rear wiper that had a fault, I was sure it was the multifunction unit not giving an ouput to that circuit, turned out to be a stuck relay... Don't overlook the obvious.
__________________
------------------------
300tdi Disco XS

Dude your a legend... That is definately getting tried tomorrow morning!

Had similar problems.Radio,clock and cabin lights are on F6 in Sat fuse box 2.Fuse kept blowing and was caused by a short in the radio circuit.Cabin lights didnt work as MFU was fried.Got one on Ebay for £15.Rear wiper will only work if all the doors are closed.
Hope this helps

S368 VOP
Senior Member
Join Date: Jun 2006
Location: planet mars
Posts: 153


Re: Ignition/lights on warning sound
Hi,

There's a multifunction unit mounted on the back of the fuse board below the steering wheel, the buzzer is located in there.
The unit controls things like intermitant wiper delay, interior light fade, rear wiper, etc. I don't know there are any fuses for that circuit, unfortunatley the unit is pretty much non repairable (i'm from an electronics background and I couldn't be bothered), if you do need to replace it I think they are about £97.00...

There is a test mode as described on the rave cd:
(same year as yours so should work)

The multi–function unit (MFU) is mounted on the
rear of the passenger compartment fusebox and has
an input to operation of the following:

Heated rear screen

Heated front screen

Courtesy lights

Side and headlights

Rear fog guard lamps

Headlamp power wash

Front wipers

Rear wash/wipe
Diagnostic Procedure
1. Close all doors and the tailgate.
NOTE: If the oil pressure switch goes open circuit
(engine is started) during the following procedure,
the MFU will exit the diagnostic mode immediately.
2. Press and hold the heated rear screen switch
and switch on the ignition.
3. Release the heated rear screen switch within 2
seconds and the MFU will beep to indicate that it’s in
diagnostic mode 1.
4. Press the heated rear screen switch; the MFU
will beep twice. In turn, operate each of the following
switches, heated front screen, rear fog guard lamps,
side lights, headlights, front wiper and rear wiper.
The MFU will beep twice each time a switch is oper-ated.
5. Pressing the heated rear screen again will cause
the MFU to enter diagnostic mode 2.
6. The MFU will provide outputs to the following in
order given below:

Heated rear screen relay energised for 2 seconds

Heated front screen energised for 2 seconds

Courtesy lights energised for 2 seconds

Dim dip relay energised for 2 seconds

Rear fog guard lamp energised for 2 seconds

Headlamp power wash energised for half a second

Front wiper energised for half a second

Rear wipe/wash energised for half a second
7. The MFU will then exit the diagnostic mode.


Hope this is of some help, if you need it I can send you a copy of the cd so you can trace the wiring diagrams.

PS. After two days trying to fix my rear wiper that had a fault, I was sure it was the multifunction unit not giving an ouput to that circuit, turned out to be a stuck relay... Don't overlook the obvious.
__________________
------------------------
300tdi Disco XS

S368 VOP
Senior Member
Join Date: Jun 2006
Location: planet mars
Posts: 153


Re: Ignition/lights on warning sound
Hi,

There's a multifunction unit mounted on the back of the fuse board below the steering wheel, the buzzer is located in there.
The unit controls things like intermitant wiper delay, interior light fade, rear wiper, etc. I don't know there are any fuses for that circuit, unfortunatley the unit is pretty much non repairable (i'm from an electronics background and I couldn't be bothered), if you do need to replace it I think they are about £97.00...

There is a test mode as described on the rave cd:
(same year as yours so should work)

The multi–function unit (MFU) is mounted on the
rear of the passenger compartment fusebox and has
an input to operation of the following:

Heated rear screen

Heated front screen

Courtesy lights

Side and headlights

Rear fog guard lamps

Headlamp power wash

Front wipers

Rear wash/wipe
Diagnostic Procedure
1. Close all doors and the tailgate.
NOTE: If the oil pressure switch goes open circuit
(engine is started) during the following procedure,
the MFU will exit the diagnostic mode immediately.
2. Press and hold the heated rear screen switch
and switch on the ignition.
3. Release the heated rear screen switch within 2
seconds and the MFU will beep to indicate that it’s in
diagnostic mode 1.
4. Press the heated rear screen switch; the MFU
will beep twice. In turn, operate each of the following
switches, heated front screen, rear fog guard lamps,
side lights, headlights, front wiper and rear wiper.
The MFU will beep twice each time a switch is oper-ated.
5. Pressing the heated rear screen again will cause
the MFU to enter diagnostic mode 2.
6. The MFU will provide outputs to the following in
order given below:

Heated rear screen relay energised for 2 seconds

Heated front screen energised for 2 seconds

Courtesy lights energised for 2 seconds

Dim dip relay energised for 2 seconds

Rear fog guard lamp energised for 2 seconds

Headlamp power wash energised for half a second

Front wiper energised for half a second

Rear wipe/wash energised for half a second
7. The MFU will then exit the diagnostic mode.


Hope this is of some help, if you need it I can send you a copy of the cd so you can trace the wiring diagrams.

PS. After two days trying to fix my rear wiper that had a fault, I was sure it was the multifunction unit not giving an ouput to that circuit, turned out to be a stuck relay... Don't overlook the obvious.
__________________
------------------------
300tdi Disco XS

Nothing to do with me and all down to ' S 368 VOP ' , who ever he is, I only Google'd it.

This bloke is the daddy

I did the test. Got all the appropriate bongs. No cabin light during the run through. Or rear wiper...

In a moment of pure dumbness i realised that the glovebox light only works when your headlights are on, so scratch that off the list...

Just my rear wiper and courtesy lamps not working

MrPDude said:

I did the test. Got all the appropriate bongs. No cabin light during the run through. Or rear wiper...

In a moment of pure dumbness i realised that the glovebox light only works when your headlights are on, so scratch that off the list...

Just my rear wiper and courtesy lamps not working

Click to expand...

Your are not reading the all previous posts then

Fettled, sorted, fixed

What a wonderful forum

Just a bit of a leak of some fluid or other to get top side of now