Rear Window Wiper Not Working , 2013 A1 , 1.6 Diesel

Hello Everyone. Hoping I can get some help with this fault. The rear Window wiper has suddenly stopped working on my daughters A1 ?
So far, all Ive looked at is the corresponding fuse for the rear wiper motor, according to the handbook and the wiring diagram I have downloaded , the fuse is a 15 Amp fuse located in the " only " fuse carrier on the PASSENGER side of the car, - car is UK RHD , just thought I'd mention that. So, Ive put the fuse back. The rear washer DOES work though, and stops when the boot lid is not shut properly, - so as far as Im concerned , the boot switch is ok because when the boot is not shut properly, theres no rear washer function, and the dash shows BOOT OPEN !
so, back to the rear wiper motor, Ive studied the wiring diagram, and it looks like the 2 relays in the engine bay , refer only to the front wiper motor, maybe one for the motor, one for the intermittent, ? so I havent looked at them at all. So, its my guess that the REAR motor is switched from the stalk switch ?? and not via any relay - I dont know ?
The wiring diagram I have shows the rear wiper motor has 4 wire connections. - wire colours as follows
BROWN ( earth )
BLACK/ WHITE ( +12 volt feed from the 15 amp fuse passenger side fuse carrier )
GREEN/RED ( labelled 208 on wiring diagram )
GREEN/WHITE ( labelled 206 on wiring diagram )

So this is where I am at the moment, - I havent removed the boot trim to reveal the motor so I can do some checks. If I do, I intend to check the +12 volts is there from the the fuse and a good earth, dont know about the wires labelled 298 and 206, I guess they go to the stalk switch, assuming theres no relay involved. Im also hoping its not that complicated that the rear wiper function is not fed from an ECU of some sort .

Thats it so far and sorry for this detailed lengthy post , but thats all the info at the moment, Thanks for any ideas from you guys.

The number, i.e. 208 refer to current tracks, these are the secret to how VAG curent flow diagrams work. If you follow the green/red wire with 208 in the box down (imagine it going trough V12) to the bottom of the page as an imaginary line you will see it aligns with 281, the numbers along the bottom are the current track numbers, so if you go to current track 208 on page 16 and follow 208 up as an imaginary line you will see it goes to the green/red with the box 281, that is the complete circuit. If it is an active diagram, clicking on the box takes you to where it goes and highlights the track from top to bottom. For the black/white power wire it is even easier, follow current track 285 up from the bottom of the page and the imaginary line passes through the brown then into the black/white and box 285, through the J519 BCM, out the other side to box 285 which shows the fuse designation. SD is the dash left side fuse box (on right hand drive) and this is divided into three strips ST1, 2 and 3. ST2 is the centre brown section and fuse 15 is the wiper fuse; it would be clearer if the labelling after box 285 was SD/ST2-15. ST15 is the next to last fuse installed vertically in line with the horizontal fuses 4 and 5. If you want to confuse yourself even more, if you look at section 802 "overview of fuses", it states that fuse carrier ST2 on fuse holder D number 15 is "fuse 10 on fuse holder D SD 15" but I think that is an error.

Thanks crasher for a very informative explanation of the VAG wiring diagram terminology and how they refer to it as current flow, My wiring diagram is simply a PDF file, but it looks very accurate because the colour coding of the connector wires for V12 , correspond to an image I looked at for a replacement rear wiper motor, ( should that be at fault ? ) - so Im making progress with following the wiring diagram and understanding it more fully thanks to you. Incidentally, its weird that the rear wiper failed after my daughter had a recent front suspension spring replaced , passenger side , that snapped, and so obviously the mechanic had to get the wheel unlocker out from the boot to take the wheel off, - so im guessing this rear wiper fault is pure coincidence ??
incidentally, do you know if the 2 wires from V12 ( pin 3 GREEN/WHITE and pin 4 BLACK/WHITE ) go directly to the steering column stalk switch please ? rather than through a relay ?
thanks

crasher, sorry to be a pain, also wondering if OBD diagnostics might pick up on something going on, before I start taking trim off and getting my multimeter out ?
thanks

A diagnostic scan of the J519 Body Control module would make sense, the other two wires go to this unit directly and this is what operates the wiper, there is no separate relay or direct connection to the column stalk. The BCM operates the wiper upon a digital CAN BUS signal from the steering column controller which itself sees the signal from the wiper switch. Often the only use for a multimeter is continuity testing and main power/ground signals. If you try and check the command signal's the BCM may detect this and shut the circuit down. The BCM can fail and be the problem but it is not a straightforward part to replace as it is a VIN security protected component and a VIP (Vehicle Intelligent Part).

Thanks for that, I'm glad my daughter didnt let me have the car today, which I was going to do, ( multimeter to hand ) I understand exactly what you mean about poking around with a multimeter on continuity testing, It all makes sense your description of how the rear wiper works.
from this, I'm not going any further because it needs diagnosing properly and taking it from there.
Kind regards

Hi crasher,
Just an update and hopefully some more help from yourself , if you dont mind please .
With Boot lid shut correctly, There is NO +12 volts at the connector for the rear wiper motor , with the ignition on, but engine not started. there is a good clean Ground earth connection at the connector also - I checked the Ground continuity from connector straight to the GND of the battery. - question is this, the 3 fuse carriers on the Driver side ( A,B,C ) dont seem to refer anywhere to correspond to the fuse for the rear wiper motor 12v supply, however, a single fuse carrier on the passenger side, think ive seen this as carrier " D " does seem to have the correct corresponding fuse ( 15 A ) - does this sound right. Also, am I right in thinking that the +12 Volts at the motor connector comes directly from the fuse ( when ignition is on ) ? - thanks in advance , - adrian

Quote:

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Originally Posted by Crasher

SD is the dash left side fuse box (on right hand drive) and this is divided into three strips ST1, 2 and 3. ST2 is the centre brown section and fuse 15 is the wiper fuse

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Passengers side fuse panel

There can be up to three strips in there, yours only has one, the feed from fuse SD15 on the black/white is direct with no interruption by coupling stations.

The black/white at pin 4 of the connector must have battery voltage ignition on (aka Line 15) and if the power to the fuse strip SD was at fault, you would have many more problems. If the signal to the motor from the BCM was at fault, the rear washer would not work and it is powered off of the green/red and green/white from the BCM

This is all if the wiring diagram on ETKA can be believed as the fuse assignment text is totally mixed up as to fuse numbers

Thank you so much for your reply. It confirms Ive been looking at the correct fuse in the passenger side fuse carrier.- only one fuse carrier as you said.
The rear washer works as it should when the stalk is pushed forward for the pre determined time for it to kick in, obviously, with ignition ON.
I am now focusing on pins 2 and 3 , the control wires - when you mention about the rear washer function- does the BCM send a signal to the motor, and this in turn, send a request to the rear washer water pump ? - what im trying to establish is to narrow the fault down to the wiper motor , - Ive made a note of the rear wiper motor assembly and it is
HW04 SW05, Satrama SA 3250, - what im thinking about is , with the motor disconnected from the loom, if I can replicate the control signal to the motor after I have provided the 12 volt supply to it ?
I cant find any data regarding the motor assembly as to if its got any electronics built it to it etc etc.
thanks - adrian

Yes the BCM provides the signal to the motor to run directly tapped off the feed to the washer pump... I feel you are over analysing motor failure.