My daughter has a 2010 Discovery 4 HSE and there are some electrical issues that may be related. Specifically none of the washers work, but neither does the horn. I am not sure what else might have stopped working, but these two are important.

I feel that they may be a common issue, but need an accurate wring diagram to chase down potential issues - and/or suggestions from anyone here where to start looking. The fuses and relays (identified using stickers in fuse boxes) all seem to be UK, BUT there doesn't seem to be power to them therefore they don't operate - any ideas of a common source of power for thrm?

Hopefully someone can suggest something that will cure these problems.

These any use?

Is the pump running for the washers? The strainers will often clog up and although it tries to operate it may well not actually be able to draw any fluid. If I were you, I'd try a test lamp on the connector for the pump before you go too far as it may have burned out if if couldn't move any fluid.

The Horn issue could well be the clock spring I expect or simply a faulty horn. You've got a couple of issues that could well be unrelated so I'd start with the easy stuff. Unplug the horn and run a live directly to it, if it doesn't make you jump, that would indicate a knackered unit.

Also check your earth points, there's one just in front of the battery that corrodes quite nicely, it sits between the Webasto heater and the battery compartment if memory serves.

In the attached diagram, the connectors that have a black circle before them are the earth points (relatively sure on that).

I have just checked the relay operation for these two items (going by the top of the fuse/relay cover in engine bay) and the horn relay operates suggesting a dead horn - need to get hold of one (eBay here I come)

The washer relay doesn't operate at all. I am loath to take wheel and arch cover off until I know that the relay operates correctly because whilst I suspect the pump(s?) may be knackered if there is no power getting there that is more fundamental.

Blob said:

These any use?

Click to expand...

@Blob thanks for these. The horn diagram would seem to be correct, however the washer shows 2 x relay but the car shows on 1 x washer relay suggesting that this may not be correct?

I can't say for sure on the number of relays. The wife has just gone out in hers again so I can't check it. Damn thing is never still!

The diagrams can be a little hit and miss as they are generic I think for all regions and options. it is odd that there is one relay for windscreen, 1 for rear screen and one for each headlight in the diagram. Looks like the headlight ones are in the engine fusebox and the others in the central which I am assuming is the one behind the glovebox.

Brother has a 2010 RRS (our D4 is a late 2013) so I might be able to do some comparisons with his but it's a bit of a pain, let me know if you get really stuck though and we'll see where we can help out.

Damenfeld said:

I have just checked the relay operation for these two items (going by the top of the fuse/relay cover in engine bay) and the horn relay operates suggesting a dead horn - need to get hold of one (eBay here I come)

The washer relay doesn't operate at all. I am loath to take wheel and arch cover off until I know that the relay operates correctly because whilst I suspect the pump(s?) may be knackered if there is no power getting there that is more fundamental.

Click to expand...

Can you swap washer relay with another of the same that you know functions?

J