short d.c.c.. issue
#1
Rookie
Thread Starter
short d.c.c.. issue
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?
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?
Last edited by Riverguy; 11-15-23 at 02:54 PM. Reason: add-on.
#3
Pole Position
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!
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!
#4
Rookie
Thread Starter
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.
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.
#5
Rookie
Thread Starter
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!
And thank you for your reply!
#6
Pole Position
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.
Hope this helps and best of luck!
#7
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.
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#8
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!
And thank you for your reply!
Last edited by Androman; 11-18-23 at 09:28 AM.
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