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Electrical Drain! do i start to pull fuses?
Posted: 18 May 2026, 18:44
by NoobyNiall
Hi All,
The van wasn't started in 4 weeks, found the battery completely dead/ murdered in fact :?
Got a new battery, Van started and started some tests, I noted it started to drain the battery straight away.
Disconnected a few cables etc to narrow it down, its only when i pull the 70 amp relay in the junction box in the engine bay that it stops the drain.
So looking for advice, to i have a ground fault? do i start to pull fuses or check my earthing points or maybe water got in on them?
Thanks for any tips / advice.
Re: Electrical Drain! do i start to pull fuses?
Posted: 18 May 2026, 19:37
by Aidan
which engine do you have ?
Re: Electrical Drain! do i start to pull fuses?
Posted: 18 May 2026, 20:37
by NoobyNiall
1.7 Diesel
Re: Electrical Drain! do i start to pull fuses?
Posted: 19 May 2026, 19:14
by Aidan
afaicr the only relay in a JX engine bay is the glowplug relay which is ignition fed
the wiring diagram is
HERE
Re: Electrical Drain! do i start to pull fuses?
Posted: 22 May 2026, 14:23
by NoobyNiall
Thanks Aidan, would you also have the change over relay circuit?
Re: Electrical Drain! do i start to pull fuses?
Posted: 24 May 2026, 19:52
by Aidan
change over relay ? que ?
I don't really do Diesel
Re: Electrical Drain! do i start to pull fuses?
Posted: 25 May 2026, 05:40
by ZsZ
By default the factory black junction box has two relays on a JX. One bigger one, the glow plug relay - which is a control unit, not a standard relay - and one small relay for the aux coolant pump.
Both circuits have battery feed so when they fail closed they can drain your battery.
A NA diesel has only the glow plug relay IIRC.
There is no standard 70A relay by factory.
Try to post a pic of the junction box which relay you are talking about.
Re: Electrical Drain! do i start to pull fuses?
Posted: 03 Aug 2026, 06:49
by firetrader
Just a quick question regarding this issue as I notice there are multiple posts on vehicle battery drains. (By the way I am not an expert so views gratefully received). I recently tidied up my wiring around my leisure battery and found my split charge relay, it had a fuse within it which had blown so I replaced it. Since then, it may be a coincidence, but my vehicle battery is needing a charge up every 10 days or so when its about 33% depleted when its not been running. I wonder whether this is a coincidence or is related? I have a multimeter, is there some quick simple tests I can do to investigate? I guess first of all I should run the engine and take a reading on the leisure battery (lithium)to see if its receiving a charge via the relay to see if its working or not? My understanding is the reading should go up a little over 13 volts? But obviously a slight increase from the norm? Then is there any other way to check with the engine off, would pulling the replaced fuse in the split charge relay for a week when the vans not running be a good test just to see if the vehicle battery is keeping its charge better?
Re: Electrical Drain! do i start to pull fuses?
Posted: 03 Aug 2026, 08:06
by Cecil
If that is a voltage sensing relay as apposed to an alternator triggered relay you have for your split charge system then it may not behave correctly if you have it connected to a lithium leisure battery.
firetrader wrote: ↑03 Aug 2026, 06:49
Just a quick question regarding this issue as I notice there are multiple posts on vehicle battery drains. (By the way I am not an expert so views gratefully received). I recently tidied up my wiring around my leisure battery and found my split charge relay, it had a fuse within it which had blown so I replaced it. Since then, it may be a coincidence, but my vehicle battery is needing a charge up every 10 days or so when its about 33% depleted when its not been running. I wonder whether this is a coincidence or is related? I have a multimeter, is there some quick simple tests I can do to investigate? I guess first of all I should run the engine and take a reading on the leisure battery (lithium)to see if its receiving a charge via the relay to see if its working or not? My understanding is the reading should go up a little over 13 volts? But obviously a slight increase from the norm? Then is there any other way to check with the engine off, would pulling the replaced fuse in the split charge relay for a week when the vans not running be a good test just to see if the vehicle battery is keeping its charge better?
Re: Electrical Drain! do i start to pull fuses?
Posted: 03 Aug 2026, 08:19
by clift_d
You need to check that you’ve got the right kind of split charge relay fitted for your wiring setup - if you have a wiring diagram of your setup that would help. For example, Westfalia campers tend to have a different relay to many standard setups as it connects the vehicle battery to the mains charger when the van is connected to a hookup - that relay is a Durite 0-727-32.
It could be that your blown fuse has been keeping the vehicle battery isolated from your leisure battery when the vehicle is switched off and that now you’ve “fixed” the fuse a possible incorrect relay is allowing something on your leisure circuit to drain the vehicle battery - we’ve previously found the original diesel heater in our Westy was drawing current when everything else was off.
Re: Electrical Drain! do i start to pull fuses?
Posted: 03 Aug 2026, 09:18
by hotpod
The question then is how is your leisure battery? Does it get much use? is it mysteriously better now all of a sudden? Does it even work?
Re: Electrical Drain! do i start to pull fuses?
Posted: 03 Aug 2026, 10:39
by firetrader
Many thanks ,its a new lithium battery , works great, with a genius smart charger,will have a go it removing the fuse from the split charger as I am registering no flow from it anyway when running the vehicle. Worth a go to see the result I feel.
Re: Electrical Drain! do i start to pull fuses?
Posted: 11 Aug 2026, 16:27
by firetrader
Removed the fuse from the split charger and no detrimental effect found (yet), van battery was about 25% depleted again after just over a week but its not been run. Not overly sure if I have a problem as I know that naturally a battery's charge will deplete , not sure, but do think something could be draining it , battery is about 15 months old.