Water pump electrics

[Mash369]

Can anyone shed any light on this issue:_

switch on electrics (either leisure battery or Engine battery) all lights etc work as soon as I switch on the water pump the lights go out switch off the pump and all come back on.

Pump works when I connect a battery direct to connections no issues.
Test wiring between pump and switch seems OK
Fuses all checked

I'm bemused, any suggestions would be help#

2004 Swift Suntour/sundance 630G

TA

Chros

 

[Markd]

Can anyone shed any light on this issue:_

switch on electrics (either leisure battery or Engine battery) all lights etc work as soon as I switch on the water pump the lights go out switch off the pump and all come back on.

Pump works when I connect a battery direct to connections no issues.
Test wiring between pump and switch seems OK
Fuses all checked

I'm bemused, any suggestions would be help#

2004 Swift Suntour/sundance 630G

TA

Chros

Bad connection somewhere in lighting circuit probably at fuse box.
The Pump pulls down the voltage generally and then high enough to overcome resistance in lighting circuit.

 

[Mash369]

Bad connection somewhere in lighting circuit probably at fuse box.
The Pump pulls down the voltage generally and then high enough to overcome resistance in lighting circuit.

Thanks for the info will give it a look at

 

[trevskoda]

Bad connection at lighting cerc as the pump pulls voltage down and if led then they cut out.

 

[merl]

Err, got to be a bad (high resistance) connection in the PUMP circuit too. ! If it wasn't then running the pump wouldn't cause a voltage drop issue. Basically it's probably a high resistance connection somewhere that's serving both pump AND lights. Don't just look in the lighting circuit ONLY, it won't be there. It could even be the main battery terminal, or a low/ dead battery even.

 

[Mash369]

Update: when on hookup everything works as expected but problems when on battery.

I have been studying the wiring diagram ( some of it makes no sense, and I'm not thick).

Can anyone expand on the control unit wiring and the location of the relays( I have tested the one next to the 12v fuses)

Ps batteries are ok and fairly new.

 

[merl]

Connect a multimeter to the battery terminals while on EHU, turn on a tap so that the pump runs and note the voltage, leave everything as is but now remove/ turn off EHU. What happens to the battery voltage?