Vs 5l ute, new everything and battery still goes flat

[ephect]

As above, start pulling fuses 1 by 1 at night and check the voltage in the morning. I'll narrow it down fairly quickly.

 

[deserthead]

Check your relays too. Could have a couple system relays (EFI/Ignition) staying on, these will drain you battery within a week.

I had mysterious batt drain too, turns out the replacement relays they put in were pinned differently and were always allowing power through into those 2 circuits.

 

[MikeC]

As above, start pulling fuses 1 by 1 at night and check the voltage in the morning. I'll narrow it down fairly quickly.

Faster to use a multimeter set to current between the disconnected battery negative pole and a battery earth. Connect it up with everything switched off. If you have a leak you will have a current. A small current will be the security system. Pull the fuses one at a time, read the current, and replace until the current gets close to zero. When the current is close to zero the leak is in the circuit of the last fuse you've pulled.

 

[wildfiremaint]

Often the rechargeable battery in an alarm will crap out onto the PCB and cause an excesive current draw.
If you have an alarm disconnect it and see if that helps.
Mine was drawing 400ma and discharging the battery.
Cheers.