I have a so far untraceable 5.5A parasitic drain on the battery of my 2015 Toyota Hilux when everything is turned off. Just to clarify, I was a motor mechanic for 20+ years, before moving into the installation and maintenance of automation sytems for airports and warehousing - cranes, robots, remote car systems etc., so I'm not a complete numpty on these things. Back to the Hilux, There are two positive cables on the battery - one is the direct starter lead and the other goes to the main fuse box. The drain is on the main fusebox line and is an absolute constant. I completely disconnected the alternator and went through all 3 fuseboxes on the car removing fuses. Nothing interrupted the drain at all. The only non factory extra was my dashcam, which I disconnected first of all. The pickup is a 2.5 diesel, has done 150,000 kms, is 11 years old and by modern standards is a very simple vehicle, but I have been stumped by this issue. I'm leaning towards it being a faulty module that's causing this, but after poring over the wiring diagrams I can't spot anything that's not fuse fed somewhere along the line. The car functions perfectly, runs and charges okay - it's just that the battery gets drained over 3 or 4 a few days if parked (as you would expect). I'm hopiing for either a Toyata expert to point me in the right direction, or an experienced current mechanic who's had a similar problem on a customer's car. I've considered wiring damage, but the car has had an easy life of on-road use and no accident damage in the past. I also considered rats eating the cables (as it once happened to a customer of mine) but can't see any evidence of this underneath, plus there is no fluctuation in the value of the drain. I'm sure I'll get there eventually, but I would love to hear from someone with a similar experience and any possible causes.