No voltage at headlamp washer pump.

[A4_MaJiK]

Having an issue with my headlamp washers not working. I actually went and bought a brand new washer pump to replace it with from TPS. Turns out I bought the pump for the windscreen washer jets (have to sell it now as I can't return electrical items apparently).

Anyway, I checked the resistance of the pump (1M Ohm) which then led me to bench test it. Turns out the pump works fine. I checked the wiring harness for a supply voltage (ignition and headlights on) but got nothing. Checked for ground on the wiring harness and both the connections (Brown & Brown+Red) were shorting to ground.

Any ideas what may be the issue here? The washer pumps fuse is fine which has led me to confusion. Also if anybody knows where I can source a wiring diagram to help, or point me in the right direction I'd depreciate it.

Thanks in advance, Azeem.

 

[NHN]

So the issue is, they don't work or are flaky?

 

[A4_MaJiK]

So the issue is, they don't work or are flaky?

Sorry, they're not working.

 

[NHN]

You're testing these with headlights on yes, have to ask as some people don't realise they must be on to work.

 

[A4_MaJiK]

You're testing these with headlights on yes, have to ask as some people don't realise they must be on to work.

Yes headlights on when testing. The motor works fine. I'm just confused why both the wires at the connector are shorting to ground tbh.

 

[NHN]

Have you checked coding is enabled & no errors showing, also can you hear the relay click?

 

[A4_MaJiK]

Have you checked coding is enabled & no errors showing, also can you hear the relay click?

Not checked anything on VCDS as I don't have access to it. But they used to work before, can the coding lose it's memory or something?

 

[NHN]

No it shouldn't, but some people play & then wonder why things don't work anymore

Which fuse did you check, possibly S237 on end of dash & also there's usually a relay that should click, try removing the trim above the drivers footwell, turn engine on, headlights on & activate washers, now you may hear the click for the screen washers, but see if you get a 2nd click for washers even if they don't work, although schematics doesn't show a specific relay for headlight washers, just the x-contact relief relay J59.

 

[ScottD3]

Can you get access to VCDS?
Plug it in, check for fault codes and do a output test.
That should give you a better idea of what it is?

Might be easier than pulling your csr apart?

 

[A4_MaJiK]

Might just do that, inspecting the relays isn't too difficult anyway. Takes 2mins to pull the footwell trim out so may have a look at that.

Thanks for the help again guys, I'll keep the thread updated with any further discoveries.

 

[A4_MaJiK]

Had a quick read through this retrofit guide for further information on the headlamp washer circuit. Looks like the control voltage is from the central control module at connector T10/Pin2. Might check for voltage output here just to be sure. Will also check wiring back to pump from there too as it shouldn't be shorting to ground as it is.

 

[A4_MaJiK]

UPDATE: Checked for voltage output at the module and it's only giving me 0.1V whenever I use the screenwash (headlights on/off). Anyway, the wire it sends the signal to (which goes to the pump) appears to be shorting to ground somewhere. Need to find out where the "A-Pillar" wire junction is as there is another single pin connection there.

 

[NHN]

I would now put it on vcds & see what it shows & coding is correct, could be an anomaly.

 

[A4_MaJiK]

I would now put it on vcds & see what it shows & coding is correct, could be an anomaly.

I can see why you'd do this but, surely the wire shorting to ground is the issue here?

 

[NHN]

Depends on how the CE module rests the wire when not in use, usually you'd think it would rest as open circuit.

 

[A4_MaJiK]

Depends on how the CE module rests the wire when not in use, usually you'd think it would rest as open circuit.

I checked the wire while it was disconnected from the CE module and it was still closed circuit to ground.

 

[NHN]

That's very strange then, check the 17pin connector in A Pillar left, remove the footwell side trim to hopefully reveal the connector blocks, I wonder if anything got wet somehow.

 

[A4_MaJiK]

Apparently it is a red/white wire at a one pin connector in black (T1a) at the left A pillar connector station. So I should find it behind the lower footwell trim on the left side right?

How does the lower trim come apart?

I'll disconnect the connector and check the wires again to try and pin down where it might be shorting to ground. Nothing is wet as such and even if it were, I'd expect a couple of other things to play up at least.

Thanks for the help!

 

[NHN]

Depends on the engine/gearbox code, but red/white is what I see for an 07 A4 but going through T17B green connector.

 

[A4_MaJiK]

Oh ok, well I know what I'm looking for anyway so will keep updating.

 

[A4_MaJiK]

Year on and got round to sorting this issue, the pump was faulty and they were also coded out of CCM.