S368 VOP said:

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.

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kjppalmer said:

I just spent a couple of hours tracing a rear wiper fault. Proved the switch worked.
proved the relay worked.
Got really annoyed with the bleeping when the key is in and the door open, and disconnected the door switch to fit a solder tag on the screw, fold the tag down to hold the switch in - no beeping!
Came to the conclusion the mutlifunction unit wasn't driving the other side of the relay low when commanded by the switch.
Haynes Manual said behind footwell panel, driver's side, so took that off. No MFU!

Came and looked at this site as quicker than finding the rave stuff. Thoughts I'd try the MFU diagnostic just for fun, before tackling the longer job of bypassing the MFU with another relay (MOT today, otherwise I'd have sought other means.)

Diagnostic worked perfectly, and hey presto, rear wiper wiped.

Could have saved an hour if i'd known about it, presumably it did a nice reset along the way.

cheers for posting it.

Discodad

Click to expand...

discool said:

The rear wiper will not function with any door open.

Click to expand...