does the hood latch need to be closed? the tutorial videos i watched didn't address this part and i'm confused as to when the system "wakes up" and if it wakes up even when the battery is disconnected.

 

Still not clear as to what you mean by 1.2

Is it 1.2 Amps?

I classify grouping as "running" with all accessories and lights, including brakes not being used all auto modes turned OFF.
OFF .. same as above and with key tiuned off and removed from the ignition and possible removed more than 25ft away from the vehicle.
Sleep ... all opening closed, double lock action. same conditions as of OFF as well. Do not open any door when you read the meter. If you open a door the vehicle comes out of the sleep.

For parasitic draw the battery has to be connected.

Before you dig deeper, just turn the vehicle off and note which fuse(s) cause drops in current. Hopefully it will be one or two.

Salim

 

yes, it should mean 1.2 amps.

not sure what autos you're referring to but i tried to make sure all the switches at the wheel were off. radio and climate off.

does the hood latch draw power? since it needs to be open while testing i'm wondering if it needs to be tricked to a closed state.

 

on the first fuse i pulled now, radio 2, it went from 1.2 to .5. what strange though is that after plugging the fuse back in the draw did not change from .5. i had to disconnect the multimeter for it to return to 1.2. apparently still too high so will try investigating some more.

i'm really confused about sleep though. when i disconnected the multimeter, i reconnected after waiting just a few seconds to see what would happen. like i said, the amps increased back to 1.2 and i pulled the fuse again which resulted in amps decreasing back to .5. but according to everyone, the system is now "woken up," and this shouldn't have occurred. do i not have to wait for system to sleep? this is partly why i stopped for today (so system could sleep).

 

imho .. too much information is causing confusion. Please add units to your measurement. Without knowing it is mA or Amps .. the values are meaningless.

I would say for now don't work on sleep ... parasitic draw ... more on this in last para below. First fix or isolate the problem.

This is the order I would follow:
What is not working. [which fuse is blown ... I suggest this first to get to working base line. No point in doing current measurements when a portion is dead.
What is drawing what current. [At least we have some info on that]. It is OK to leave the fuse out to help diagnose for a time being.
Disconnect the antenna motor. IMHO you have spent enough time going around the issue. 1hr of work should put this to bed.
Then get into the parasitic draw issue.

Food for thought: The radio fuse supplies power to antenna motor. The antenna motor has a built in "retract mast" function. Trigger for the function is accessory being turned off [it can the through the radio]. The antenna motor operates even when the ignition switch is off to continue retracting the mast. Analogy is wiper stalk switch ... if you turn it off when the wiper is away from rest position, the motor completes its sweep * [alright the wiper motor stops halfway if you turn off the vehicle, so there is a difference with antenna motor ... but I hope you get what I am trying to state].

Last para: Once you disconnect the battery power and reconnect, the system goes into reset. [it can be small reset or major reset depending one the duration of the break]. When ever you get to the point to parasitic draw, do not break the battery connection. Partial reset happens when ever you turn off the ignition key and full reset happens when the battery (supply) voltage is cut for say 15 mins (number pulled from the air)

Salim

 

IT WAS THE ANTENNA!!!

couldn't remove the motor with the mast still attached but after some sweat pulled out the power cable. when i tested and pulled fuses again i didn't realize that i hadn't closed the trunk so there was still a draw (which is odd because the dome light didn't turn on). checked a few days later again and it read ~0.4 amps so thought i'd try pulling fuses again which i didn't get around to until today. but today when i attached the multimeter, it again read ~0.4amps... but only initially. when i was about to pull a fuse, i saw it change to 0.05amps!!! i was confused. i opened a door to see what would happen and it went back to ~1amp. closed the door and it went to ~0.4amps initially again until it dropped to 0.05amps 15 seconds or so later. i'll check again a few more times but i'm hopeful that nothing's wrong now!!! or maybe there is a failing actuator somewhere that i heard from the inside but at least it doesn't seem like it will be mystery.

crazy how it was actually the problem that i thought could cause a draw awhile ago.

thanks everyone, especially salim!

 

The problem seems fixed. The test reading hovers at various stages (which can be misleading) before finally settling at .04-.05 amps.

another thing is on my vehicle the hood doesn’t seem to draw much power at all. Maybe .02 amps. So next time I wouldn’t even bother closing the latch while testing.

 

I had an almost identical issue with my 2001 RX300. Had a .04 amp draw on the electrical system. Should only be only about one tenth that much. Just enough to keep the memory in the ECU and the clock and radio settings alive. Did all the stuff about pulling out fuses to see which circuit it was in. Pulling fuses to find a parasitic battery drain works find on vehicles with circuits that control light switches, relays, ect,... But it only works so well on cars with control modules. I was able to do the same thing that you did. And pull a fuse and get the drain to drop from from 0.04 amps to .005 amps. But that would only lead me to a body control module that controlled and or monitored certain circuits or functions. I hated to to it but I bit the bullet and went to the local Lexus dealer and had them find out what it was. Turns out it was an actuator motor on the front drivers side door. When you close the door, there is a motor that drives a mechanical mechanism that tells the body control module that the door is latched. And if the motor or the mechanical mechanism isn't working. The body control module things that the door is still open and that will make it draw more amperage. I was able to by a replacement front left driver's side door lock latch actuator. For a 1999 to 2003 Lexus RX300. Part number 69040-48020 for $14.95 plus shipping. Getting the door panel off was bad enough. But the real pain was getting the mechanical lock mechanism removed. The door lock latch actuator to attached to the mechanical lock mechanism. After I got that all taken care of, my problem with a parasitic battery drain went away.

 

Thanks for the info. One question though: If the body control module thinks the door is open won't the interior lights and headlights stay on?

 

All I can say is that answer lies in the area of how the body control module is set up. And without having a detailed electrical schematic, that's hard to know for sure.

 

In building a mouse trap Lexus added features like "auto turn off the headlights" . The dome light has ON button along with door-ajar_sensor [I don't remember if the On is overridden with auto or not, but it should not].

You need the wiring as well as the info as to what the software does.

I would suggest, use/enjoy the vehicle. As long as a reputable 12v battery gives you 4-5 yrs of life, ignore the details.

Salim

 

Before I was able to determine what was causing the parasitic battery drain. I did three things. First one was to place master disconnect switch on the positive battery post. But turning the power off meant the clock and radio stations needed to be reset. Second was I got a battery maintainer. Hard wired it to the battery. Ran an extension cord from the house to the driveway and plugged it in when I parked the car in the driveway. It kept the battery charged up because it put out more charge than the parasitic drain. Last thing I did was place a toggle switch in line with all the incoming power going to the driver side door master window control switch. There were three that I could locate that were hot. The switch had three throws on it so I could shut them all off. I would turn the switch off and it would eliminate the parasitic battery drain. Problem with that was that when I turned it back on, for some reason only the drivers side window would go up and down. But I found out if I turn the master shut off switch for just a moment and back on again the rest of the window work again. And the clock and radio stations did need to be reset.

 

I went through dozens of recommended diagnoses and came up with nothing. Then one day I noticed that when I turned off the ignition, there was a tiny clicking sound coming from the CD cassette in the glove box. So it was for sure using battery power to do whatever it was trying to do, so I slid out the cassette and left it out. No more battery drain and since who listens to CD's in their cars anymore, right? It now lives in a box in my shop and I have no more power drain. As I said, long shot. But worth a try.

 

so after leaving negative battery terminal disconnected as usual, i came back to my car to test the draw again.

but something is very strange now. the multimeter is no longer testing in series (reading of 0 amps and car doesn't seem to power on). i haven't changed or done anything differently. i even tried another multimeter. both are not working. anyone have any clue what's going on? the battery is good and car runs but now i can't test for parasitic draw.

 

What test meters are you using? Sounds like you blew the protection fuse in both of them.