I've searched previous threads but couldn't find anything to solve my problem.

Something is draining my battery. My mechanic tested and found the fuse under the hood (1998 GS300) labeled MPX-B is drawing current constantly. Does anyone know what this 10A fuse is associated to?

 

my 1998 LS 400 has the same issue and i cannot find any other info myself, but.... when i pull the fuse my door locks,and my auto adjust tilt steering does not work......but the manual tilt works. i find this a little weird as we both have 98's and no info.

 

I'm havering the same issue mine is a 2000 my guess is there's a computer or relay that's associated and controls those things.

 

test your accessory electronics like power locks, windows, anything not mentioned specifically by the fuse diagram.

 

my 2007 ES350 keeps killing the battery. I measured the parasitic draw at 70 to 80 ma. Anybody know if this is normal? Online forums suggest 30 to 50 ma to be expected. The fuse under the hood in slot # 34 is a MPX-B 10 amp fuse labelled "meters" in the manual. It alone draws about 30 to 40 ma. What is on the "meters" curcuit?

 

I believe this is the Multiplex Communication System fuse. Unplug it and see what doesnt work, iirc it controls everything LoL like power windows, locks, radio lights etc. Its just a guess, but it may be a unit like body control module or something.

 

Your Vehicle: 2000 Lexus GS 300 L6-3.0L (2JZ-GE) Vehicle » Diagrams » Electrical Diagrams » Power and Ground Distribution » System Diagram » Power Source (Current Flow Chart)
See attached for my 2000 GS-300 same problem.

 

Shoot, even after finding the fuse for the system drawing amperage, you still have a lot of areas to check. That's a lot of stuff protected by that same fuse! My first suggestion is to go to all of your doors, seats, sunroof, etc. and make sure there are no switches jammed on. Activate everything and see that everything works and stops working when you stop pressing on a switch. Make sure the door switches are registering that the doors are closed. After basically switching everything you can, check again for amp draw. Maybe you will have unstuck the switch. Power seats and radios are a common amp draw from what I've seen.

 

Did you ever find a fix??

 

this was over 10 years ago so long shot but did you ever find out what was causing it??

 

Ever figure it out?? I’m having the same problem.

 

BCM, but make sure it’s corresponds to your preface lift and facelift models. I’m having that issue and I just helped diagnose the issue for one of my friends

 

whats BCM?