power drain on my 2000 LS400

[jerryparks]

I have a power drain on my LS400 - even with the key turned off. It has started to run my battery down fairly rapidly.  Any ideas what to check first?  MY mechanic originally thought it was starter related, but the starter seems to operate OK at all times.  

[jerryparks]

Added comments:   There are no codes displayed and no " check engine " lite.

 

[LSPaul]

Sounds like you have some sort of parasitic drain issue going on ("parasitic drain" should be part of your search phrase online). 

There's plenty of guides online (both pages and videos) on how to discover and measure current draw in car circuits, even with the key off (across fuses, on main power, etc). At minimum you'll need a multimeter (a digital multimeter/"DMM") and... patience. It could be a number of things--a bad alternator, open switch turning a bulb on (think trunk light or glove box, etc.), an ECU or other component somewhere in the car going south.  Also check connections (main ground, check for corrosion, etc).  To have a shop dig into it could quickly become spendy, as this is somewhat time-intensive work, and the fixing doesn't occur until a good tech actually does the work diagnosing which circuit or component is responsible for the current draw, even with the key off.   Read/follow the guides and that should help you narrow things down.

Let us know what you discover.  Good luck!

Paul

 

[schujd3]

Hook up a multi meter to your battery set it to volts and if you have them use alligator clamps. Afterward start removing fuses/relays one my one while checking the multi meter. Once you find the fuse or relay that's causing it the drain should stop and you will have to check that entire wire harness that runs to that specific fuse. You can follow the wires under the fuse box. Also check the inside fuse box as well. It'll be harder to track the wires though if there's a drain coming from the fuse box inside because it's cramped. This method worked on my jaguar and I found the short by tracing the wire down from the relay or fuse from the fuse box. 

Goodluck