Riverguy

This has been addressed here before but with no clear answers. '01 RX300. Battery drains overnight, but only occasionally. Last night it drained so I today connected my voltmeter across from the battery negative post to the disconnected cable. The reading is 12.8 V. When I pull the "Short D.C.C." connector, the voltage jumps up to 13.2, so removing this connector eliminates the drain. Then with the connector back in, I pulled every fuse in the box, one-by-one, and none showed a change in voltage., so none of those fuses is servicing the culprit circuit. I understand what this connector is for and that it disconnects a lot of non-essential circuits during vehicle shipping, etc.

So the big question remains: How do I find exactly what is on the D.C.C. circuit but not fused by any fuses in the box? Does anyone have a list of the items/devices that are on the D.C.C circuit so that I could disable each one, one at a time, to find the culprit? What makes this difficult to diagnose is that it happens only occasionally, like this morning when I had to get my wife to her Chemo appointment 50 miles away from home!

Any help here would be very much appreciated!

Add-on: An eve more useful reply to this question would be which device on this circuit is the most likely to be causing this intermittent load? There are lots of questions about this particular issue. There's gotta be a really bright electrical genius out there who knows these cars really well! Right?

brandonfpv

When exactly did this happen, right after starting it?

Arsenii

Hello,

Did you try measuring how many amps the Draw in question is consuming?

From the 2000 ES300 diagram (which should be fairly similar to your RX), the Short Pin that you described powers DOME and ECU-B Fuses, you should be able to check it by disconnecting the battery, pulling both fuses and the jumper out, and checking the Continuity between the Jumper and the Fuses. My only assumption for why you were able to fix the draw in the case you described would be that something else was active in the car that got reset when you pulled the Jumper out.

Here you can find the procedure on how to check for Parasitic Draw without pulling any fuses. It is crucial to wait for at least 10-30 minutes after you leave the car before proceeding, and it would be helpful to temporarily bypass Door Switches to ensure you won't trigger them by accident. Intermittent issues like the one you described can take a while to show up, sometimes they require you to start looking into your own actions that can trigger the draw. The only way I was able to think of so far is to get a Clamp Meter with remote access to monitor the Current, and react right when the issue occurs.

You can also try taking the Jumper out and driving like that for a while, granted it will disable some of the car's functionality, but it will provide a definitive answer on whether it is the Jumper and its systems that cause the draw.

I've had a similar issue before, but mine turned out being quite simple, as it was caused by a slam dunk aftermarket radio install, with loose wires dangling behind the dash, I had to replace the entire harness because of it, and I am still bitter about it.

Hope this helps and best of luck!

Riverguy

Thanks for your reply! I've checked all of those and more! This thing is also intermittent, making it a whole lot more difficult. Sometimes it goes fine for weeks - or longer - and then one morning when we REALLY need the car, the battery is stone cold dead. When it's in that condition I can run tests on it and that's how I at least isolated it to the D.C.C. circuit. There's gotta be a second fuse panel in this car somewhere, but I haven't been able to locate it. I keep finding diagrams showing it behind the left front kick panel under the dash. NOT!! So now all is well again and there's no load on the battery with the car shut off.

I'm thinking of selling our precious RX300 since we can't depend on it anymore. We LOVE this Lexus, but hey. maybe it's time.

Riverguy

It happens, I guess, when SOMETHING does not power down when I shut off the ignition. When I notice it has happened is the next morning when I try to start the car and the battery is dead. That's when I get the chance to run tests on it and have been able to at least isolate the problem to the D.C.C. circuit. Please read the next reply to another question for the complete rundown on what's going on here.

And thank you for your reply!

Arsenii

I wouldn't rush with it too badly..

Here is an Owners Manual for your car that shows the panel right behind the storage cubby to the Left of the Steering Wheel, that's where it is located in my 2000 ES300, which, again, should be very similar to yours. You need to open it and then pull it up sharply, which will release the clips that hold it. While I do understand that you checked it, but I am telling you it IS there, it HAS to be there, it's not like there are too many places in the car to hide one of those..

Even the most random of issues still have some merit and Logic to them, it's just that you didn't grasp it quite yet. The only way to find it would be to stay mindful of your own actions, what you do differently before the battery runs flat. I've had a flat battery a handful of times, hate to admit it, but the vast majority of those were caused by own bonehead moves, which usually included leaving some lights on.

For example if the issue only happens when you park the car in the Night, or roll the window up, it could be that the Integration Relay doesn't shut off, leaving some systems on, which will drain the battery. Be sure that when you leave the car, All the lights in the interior are off, especially the Driver's Window Switch, that's a good sign that the Integration Relay switched them off, you can also come to the car with a multimeter for a few nights to monitor the Current, which would give you a better chance at sneaking up on the issue. Repeating majority of the same steps won't help you much.

As mentioned before, simply try pulling the Jumper out for a few days, see if the issue returns, or you can only pull it out overnight, but I am not exactly convinced that it will be easier, or more productive.

Hope this helps and best of luck!

Pwrdude

Pull open the little storage box by your left knee. That drawer comes out. Behind it, is the fuse panel. The panel diagram is on the back of that storage box. This time, connect your multimeter between the disconnected battery cable and post, in series, and set it to amps, not volts. While looking at the meter, pull one fuse at a time until the amps drop to zero, or at least a big decrease.. That should tell you which circuit has the problem.

Androman

This might be swinging in the dark, but when you turn the car off, do you by any chance hear a "gerbil" type noise kinda under the shifter/glove box area? I just wonder if it could be the recirculation servo has crud in the motor, and something like it makes the motor freak out because it cant land where it wants to, draining your battery if it sits for a while. Mine does this, but i can turn it off so it sucks air from the outside and it stops freaking out squeaking and whatnot.