Zig problems

Hi looking for advice 
I have a VW autosleeper Topaz year 1999
Leisure battery is fully charged and everything works on 240 v. 
When on 12v lights work but water pump doesn’t
If lights are on and you turn on the water pump on Zig panel lights go off and nothing works. 
Any help appreciated 
Cheers Wharfy

Some one will be along soon, as plenty of advice about VW on here.

Hope you get it sorted.
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Richard

Many thanks Richard

I am surprised you have not got any help yet, maybe out in the sunshine.
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Richard

Possibly. The problem only occurred recently so hoping it will easily be remedied

It's an unusual one, it seems! Presumably when you turn off the water pump everything else goes back to working normally???

Offhand I can't think of an obvious cause. If it were mine I would put a meter on every part of it, but can't do that remotely!

So... when you are on EHU, all of the 12V appliances work Ok. When disconnected from mains, any higher current appliance causes the 12V supply to fail?

I've seen exactly these symptoms, but in a very specific set of circumstances. It quite likely will not apply to you. Do you have a solar panel?

The water pump is possibly stealing all the capacity that the battery can provide !
Check the battery voltage off load and see what effect the pump has on this reading.
A healthy battery should have an off load reading of 12.7v or 12.8 v
The pump should not have a big effect.
Keith

Thank you both for your responses. Yes everything works when on EHU. Battery readings are good 12.7 When I switch off water pump the lights work. No solar panel. Really strange

Without being able to put test gear on it and measure voltages at various points it's pretty much impossible to diagnose a problem like this from afar.

But I would be looking at whether there is a fault in the connection from the negative side of the lights to the vehicle chassis. Faults like this are typically due to broken ground wires.

Ok thank you.....will get someone to check as I have no idea 
Regards  Wharfy

In the past I've had  a bad connection on a leisure battery fuse which only showed up when the load increased. Easy to spot since there will be heat damage. Also check the relay connections.

Many thanks will get this checked out as we're novices. We've taken the front of the Zig panel off and all looks ok there....all was working well last Summer/Autumn and we have regularly taken van out to keep battery charged this year but last week we started to have this problem
Regards Wharfy.

I had a very badly corroded joint under the front seat of our Topaz, yes inside damp? which caused the hazard lights to flash at strange intervals. When I googled it there were loads of others who had the same problem.

Maybe you will get answer on Google, I found that VW's seem to be prone to electrical problems reading on forum sites, although our's was a T5.
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Richard

rgermain wrote:I had a very badly corroded joint under the front seat of our Topaz, yes inside damp? which caused the hazard lights to flash at strange intervals. When I googled it there were loads of others who had the same problem.

Agreed - it's a very common issue on pre-2010 T5's (later models did not have that control module under the driver's seat, so no vulnerable loom joint). But it should not have any effect on the habitation electrics, as far as I can tell.

It is a mystery. Have checked all fuses and they seem ok
Thanks anyway for suggestions

I'll say at the outset I know nothing about your van. A-S used to supply a wiring digram for their vans, until I suspect they outsources the electrical side to Sargent,

Just suggestions then, with the van off EHU, open a water tap and track back with a volt meter from the pump to its switch. The negative at the pump, looks to be grounded because it works on EHU, but connect a wire from the pump's negative to the chassis to check, does the pump still not come on, if not it's the positive where there's a fault. A switch or fuse are likely to be where there's a fault, a spade connector could also be in the frame. The switch which controls the pump, can you gain access, is the switch receiving power, if not it suggests a fuse issue?

Thank you for your suggestion. Tomorrow I'm getting someone to take a look at what you and others on here have suggested to remedy the problem. I will post the results here tomorrow. Fingers crossed it will be an easy fix
Regards 
Wharfy

Not found fault yet but have someone coming with meter in the next few days to check all electrics etc

Problem solved. It was a relay switch under the bonnet. Thanks again for your suggestions