Rear windows not working

[VRS Nick]

Hello all , I have a Skoda Octavia fl TDi vrs and I’m having problems with the rear windows not working . It keeps blowing the fuses which are a 30amp . I’ve unplugged the all the doors one by one and tried a fuse in each time and they still blow .  When I tried a fuse in last time I heard a crackle/spark behind the dash under the steering wheel . Could this be the problem or is it sparking there due it begin a weaker part ? 

[MikeTheThinker]

Sound like you have a short to earth somewhere and you'll need to sort it pronto as it may be a fire risk.

 

Are the fuses you are replacing on the internal fuse panel or under the bonnet?

 

[VRS Nick]

Internal fuse panel . Just the rear windows fuse have blown nothing else . Front work fine . There’s no fuse in at the moment for the rear windows 

[MikeTheThinker]

Is it possible the sound you heard could have been the rear window fuse blowing?  Perhaps recheck by renewing the fuse and observing the fuse panel as you operate the rear window switch?  Remember to protect your eyes, too!

 

A common cause of problems (which you may have checked) is the door harness which gets a lot of work over time as it flexes every time the door is opened or closed.  Breaks can occur to the conductors inside the insulation and can then "poke" through the insulation and short out, or the outer insulation can fail giving a similar result.

 

Pulling trim panels as appropriate to allow a close inspection is the next step.

 

Just in case, try unplugging the door harness for the rear doors one at a time and see if the problem persists.  That should help narrow it down a bit.

 

[VRS Nick]

No definitely came from behind the dash the crackle . The fuse  blows as soon as it’s inserted . Before hand they worked then after a day or so it would blow  guess down to overheating . Not sure if the front windows are on the same wiring circuit as the back but they all work fine . They also worked fine until the rear window fell out of its holder and fell into the door , fixed  that and since then they blown the fuse .

I’ll pull the door harness back when I get home and see if I can see anything . I’ve also pulled the harness for the rear doors and it still blows the fuse 

[MikeTheThinker]

It sounds as though you may had had a prior problem (before the glass dropped down) due perhaps to either a failing window motor or failing wiring somewhere, and that this has led to or exacerbated a failure of the insulation on the switched feed from the window relay on the fuse panel to the door in question.

 

If you have disconnected both rear door harnesses and the problem still persists then I'd say you have a permanent short somewhere between the window relay and the doors BUT I'm puzzled as to why you should get shorting on both rear doors - unless the prior shorting has essentially burned the two feed wires together.

 

I don't have my Haynes to hand but I'll try to check it later tonight after Tai Chi and see if there are any clues therein.

 

[VRS Nick]

Possibly pal . It’s live all the time without the ignition on . If there’s a live somewhere on one of the rear doors it would still blow the fuse as there on the same circuit.. if I have one door love it still blow I’m thinking for both . If you could look at your manual I’d be really grateful.

[MikeTheThinker]

I have to apologise but I can't locate my manual at the moment; I think it's in our other Octy 2 at our daughter's place 😞

 

I'll have another look for it tomorrow but in the meantime our electrics expert may be able to help - @langers2k

[langers2k]

Certainly sounds like a dead short somewhere if it's popped multiple 30A fuses.

 

Looking at the wiring diagram, there are two fuses that provide power to the rear door control modules.

- SC32 30A, should be a red wire with a green tracer and only feeds the two rear door control modules.

- SC34 20A, should be a red wire with a black tracer and feeds the BCM and two rear door control modules.

 

Given you've mentioned a 30A fuse, SC32 seems likely to be the one you're having issues with.

 

 

I'd start by disconnecting the 8 pin connectors between the car body and both rear doors. If there is still a short, then the (first?) problem is likely to be a chaffed wire somewhere, probably where you're hearing the sparking sounds in the dash

 

While the two 8 pin connectors are disconnected, you can also check that neither pin 2 or 8 are shorted on the door side. This will confirm there isn't a second short somewhere in the doors which may have caused the other short.

 

[VRS Nick]

Thank you for this ! I’ll try and take the dash apart this weekend and see if I can see anything . Definitely heard it behind the dash and I did do a silly thing and hold the fuse there but if I didn’t I wouldn’t of heard the spark noise . Unsure how or if a wire would be chaffed behind the dash tho unless it’s wear and tear ? 

[VRS Nick]

Right I’ve pulled the white/yellow fuse thing on the left and put it back in . I’ve tried a 20amp fuse should be 30amp but haven’t got one and it didn’t spark . Tried the rear windows and only the drivers rear worked . The passanger side didn’t . I’ve really done nothing to make it work apart from pulled that fuse type out and back in 

 

The window switch on the drivers door when no fuse is in you press the drivers rear button to go down you hear a clicking BUT don’t on the passanger side BUT you hear the clicking on that side when you press to close the window . Oppsite way . 

 

Hope that makes sense . Any ideas ?

[langers2k]

The white/yellow thing on the left with 644 on it is a relay, not a fuse.

 

It's possible if it is a chaffed wire, it's no longer touching the body so it's not shorting. Wires can move about as you drive over bumps etc so it may short again in the future.

[VRS Nick]

Do relays fail ? Didn’t really move any wires . Not to make a difference I don’t think . The internal fuse box holder isn’t live anymore . The  passenger rear window just clicks now when you try and use it from the drivers switch and the door switch . Could this be the motor itself that’s not working for it to do this 

[langers2k]

Relays certainly can fail but I doubt it's related. Both the fuses I mentioned earlier are connected to terminal 30 which should be direct from the battery, possibly via fuse SB29 (50a).

 

You probably have moved some wires even if it's unintentional, I recently had a fault which would occur every time I turned right as a connector moved...

 

What do you mean by the internal fuse box holder isn't live any more?

 

Have you checked for power at the rear doors on the pins I mentioned?

[MikeTheThinker]

Relays do fail, usually by failing to operate (which can produce a "click" with no action as you are experiencing) or less commonly by fusing in the "on" position which means you can't turn off what you're trying to control (doesn't sound like what's happening for you).

 

You can test relays with a resistance meter which can tell you whether the contacts are open when they're meant to be and - if you have the technical spec to hand - you can measure the resistance of the actuating coil to determine it's health.  If you don't have such facilities available just buy a replacement from your chosen auto-electrical supplier; relays don't cost much and it's usually worth having a spare on the shelf rather like your spare fuses.

 

Having said all that, just getting a click when you operate the switch could also mean the relay is actuating correctly (the "click") but whatever it's trying to enable downstream isn't working.  Window motors tend to work or not, and other failure areas include connectors (again!) and the window regulator mechanism which is usually driven by a piece of wire like your Granny used to use to hang her window mesh.  They can and do fail and aren't repairable.

 

[VRS Nick]

1 hour ago, langers2k said:

What do you mean by the internal fuse box holder isn't live any more?

When I put a fuse in for the rear windows it was sparking as tho it had power to the fuse location .

 

the clicking noise is coming from the motor in the door . I’ve pulled the door sleeves back to look at the wires and can’t see anything standing out . Had both rear door cards and drivers door card off and had a look at the wires and plugs going in to the modules and can’t see anything . Looks all clean . 

[langers2k]

Fuses shouldn't normally make sparks when you're putting them in, if they are, it suggests something is trying to pull lots of power, for instance, a dead short. You shouldn't just keep replacing fuses if they are blowing, it'll just increases the chance that whatever the fault is can damage something including the wiring.

 

As for the clicking noise, I think there is a relay inside the door controller to power the window motor. Just because the relay is moving, doesn't mean there is actually power to the motor as it may take a different power feed given there are two per door controller.

 

You need to verify both rear door controllers are getting power to both pins. If you haven't already, get a multimeter and please use it to do some basic checks as mentioned previously...