davidc96

Hi CL,

I conducted the usual multimeter test and discovered that my vehicle (2007 RX350) had a whopping 1.3A (1300mA) of parasitic draw, even hours after doors are locked and car was left untouched.
So I went through the grueling process of plugging/unplugging all the fuses in the vehicle and narrowed it down to two fuses in the fusebox right next to the battery:

1. ECU-B (#24 in the manual) - drawing 0.6 to 0.7 amps
2. CRT (#13) - also drawing 0.6 to 0.7 amps

The ECU-B is connected to a ton of things (power windows, A/C system, moonroof, wipers, etc) so I tried to fix the issue with the CRT circuit first (manual simply says connected to "audio system"). Keep in mind this is a stock system, no aftermarket upgrades or anything.
I unplugged all chargers and dashcams that were near the audio system to see if that would help but that did not work. I've yet to take out the radio/stereo to see if the wiring behind it was OK but decided to see if anyone here had any ideas of what might be causing the draw on a stock audio system? Could the draw on both ECU-B and CRT somehow both be related due to any shared wires? I'm clueless as to what to do. My battery was recently replaced and was at 100% charge @ 12.8V so I'm sure it's not the battery at all.

Thanks in advance!

Margate330

There are some components stitched together in one way or another in these circuits for the fuses you mentioned depending on your options

Do you have Navigation or rear seat "entertainment displays"?

Here are 3 fuses you can try to see what hapens.

1) Radio #1: Battery power to radio

2) Radio #2: Accessory power to radio & stereo amplifier(under rear seat) & rear video displays(if equipped).

3) AMP: Battery power to stereo amplifier.

Also, my wiring diagram shows fuse CRT is battery power to rear seat "Entertainment System/Display".

davidc96

Thanks for the info Margate330 -- yes, I have a navigation system but I do not have rear seat displays.

1. There's no way to check this unless I open up behind the radio, correct? Will have to set aside a couple hours this weekend to check this..
2 + 3. I tried to look for the stereo amplifier under the rear seats - not sure what exactly to look for. How can I go about getting access to the wires for this?

Seems strange CRT is battery power to rear seat displays when my vehicle doesn't have, any thoughts as to what else CRT could be powering?

Margate330

Ok cool,

Here is a list of things for CRT fuse. Some of these things are stitched into other things- thru the "Multibean" network via the Body ECU- your ECU-B fuse is for body ECU as you say.

So, you can quickly rule out the Nav/radio/amp issues by pulling those 3 fuses listed in previous post and also rule out interior light circuit by pulling the dome fuse(by brake reservoir).

It would be helpful if you found some other fuse that wasn't so broad in scope- if possible because these 2 fuses you pulled(CRT & ECU-B) cover quite a bit.

PS- the reason I went for ruling out interior lighting and radio circuits first is because of your amp draw and it's easy- and it's also downstream from the NAV
Also, stereo amp fuse and dome fuse is under the hood by brake fluid reservior, radio fuse is under dash.

Margate330

Just to give a taste of what the CRT & ECU-B fuses cover... lol

CRT fuse also goes to NAV and rear entertainment(which you don't have) and the Nav is stitched in to the stereo, stereo amplifier, climate control, security system, etc, etc, etc

So the NAV Display goes upstream thru the Gateway ECU to the Body ECU and the NAV goes downstream to stereo, stereo amp, dvd map ecu & camera ecu- any of these components can "wake up" the body ecu. By killing the power to the stereo amp and radio you can rule out some of the downstream components from the NAV.

This is just a starting place for the diagnostic-hopefully others have ideas.

iMSQ

+1
https://www.clublexus.com/forums/rx-...l#post10855402

davidc96

So I've managed to rule out all your suggested fuses - pulling out all of the fuses one by one near engine and under driver dashboard do nothing else to the amp draw. Seems like this problem is isolated to just the two mentioned fuses, CRT and ECU-B. I'm stuck now, unsure of where to even begin with other alternatives since the obvious ones have been ruled out.

Margate330

Ok cool so this is a good start.

If it was my car next thing I would do is pull the MPX B fuse to shut down the Gateway ECU and see if it improves(killing all communication to Body ECU from the Gateway ECU downstream)

Then I would pull the "Nav/multi-display" and pull plug B in the pic below and contine pulling the rest one at at time if still no improvement and see what happens.
PS- if anyone is wonderig, the plug in pic below goes to CRT fuse- if the CRT fuse goes directly to anythng else I haven't found it yet but still looking...

Brucecav

I just had the same problem with my 2004 rx330. I found the draw was .78 amps on my ECU-B fuse as well. That was the only one that I had the issue with. When I pulled the fuse it went down to 0.1 amp which is normal.
Here is my mystery with a good ending....
I saw the ECU-B was connected to many things as well. But i pulled the fuse anyway and tried them all and they ALL WORKED WITHOUT THE FUSE IN!!
I have no idea.
The only thing that stopped working was the power locks on the doors. I have been driving the car for a week now without the fuse in it and it seems to work just fine (if you can live without the power door locks)
My parasitic draw is gone. So thats where I am at. Please let me know what you find, we may be able to help each other a lot.
Bruce

SCGolfer

I had my daughter's 3004 RX330 suddenly have this same issue.
It started with bad voltage regulator in alternator.

I have replaced with new.
Battery, alternator, starter (solenoid had large parasitic drain), power control module.

I installed a used 24K mile pull out Multiplex body control unit.

I haven't measured the amount of draw as my meter only does AC.
After inserting the fuse the meter goes from 12.62 straight down to 12.58 and every three minutes loose another .01.

As soon as I pull the ECU-B fuse the battery goes back to 12.62 and stays.

The seat memory buttons stopped working.
The windows all reset to auto.
The sunroof has reset to auto
I have pulled the stereo completely out the only thing I haven't done is disconnect the amp.

The weird thing that started happening is when you get in the car and close the driver's door the locks activate to unlock on their own.
If you unlock via remote the driver door unlocks without a beep. If you press the unlock a second time all doors unlock and it beeps.

I have done the reset / change settings and they work. I don't know if there is a controller somewhere that may be causing it.

I would love to know where to go next to work on this issue.

SCGolfer

Ok wanted to follow up on what I finally did and seemed to fix drain.

I did not have dc amp draw meter but short was strong enough as soon as fuse was put in the battery voltage dropped immediately l was able to trace fuses that may have been problem.
So I put the ECU-B fuse back in and tried other fuses and found the dome fuse was actually the problem. I then opened the back up and unhooked wireless controller and Multi body controller.
With the dome fuse back in with these unhooked it didn't have a drain. I then was tried smaller connector on multi controller and no drain. The longer connector it started again.
I then shut off the dome lights, unhooked the light trim on door sills, unhooked all the door lock / window switches.
Battery drain stopped.
I started connecting sill trim lights, good,
Then each lock window switch starting on passenger side.
Found there was a short in drivers controller. I had an older OEM to try and all good now.

Car back to normal.

Margate330

Excellent job!
Thank you for sharing your fix and should be considered a must read for parasitic draws. IMHO
This goes to show how well these components are stitched together thru the Body ecu when the parasitic draw is found on the Dome fuse but the failed component is the Driver Side Window/Lock Switch.
You did have a clue with the locks showing strange symptoms that could be considered for anyone going thu this.

matts6887

see; im not sure that i would ever notice if i had a issue like this one because my rx doesnt sit; its driven every day for a good amount of time so the battery is always being charged while driving it. but then again i suppose anything is possible and i may notice if something funky is going on.

Brucecav

Thats great! I would like to get some more detail on some of what you did. I have same problems and still trying to find where the drain is. Someone told me once that the electronic controllers on the doors go bad.likely a rear door. I would hope you can guide me with this process. Where was the multibody controller unit found? If you are willing can you email me at golferguy@hotmail.com. I have some more specific questions.
Bruce

SCGolfer

I sent an email.