espilman

I have a parasitic draw on the ECU-B fused circuit in my 2004 RX330. Anyone have any ideas? It draws about 350ma and drops to 20ma with the fuse pulled.

DennisMik

Are you having a problem or is it that you discovered the draw. All of today's cars have a "parasitic" draw because of the alarm system, the remote entry system, the clock, the radio and probably a few other things. But I don't know what the amount of the draw is on these cars.

espilman

Yes, The battery dies anywhere from 2-7 days. The battery is good as well as the generator. From what I have determined, the "normal" draw is around 20-30ma. The draw on this 2004 RX330 is about 350ma. If I pull the ECU-B fuse the current goes down to the 20-30ma range. It really sucks that there is so much hanging off of that single fuse. I fear it is not going to be easy to determine what item is causing the problem.

ToledoRX

Are there any aftermarket electronics installed on this RX (i.e. Radio units, wi-fi systems, radar detectors)?

If not, how many previous owners did this RX have? Some used lots install GPS units on their cars to make it easier to repo if the customer are unable to pay their loans.

espilman

Thanks for the reply. There is a phone kit installed but it is on a different fuse. It is a one owner car and nothing has been added in the past 5 years.

DennisMik

I found that the ECU-B fuse supplies power to the "center cluster integration panel", whatever that is. It could also supply power to other things, but I did not see any other references.

But another thing about the normal draw, is that the car's security system will draw more power when a door or hood is open. When everything is shut and all switches are set, the draw will be reduced after a half minute or so. So try monitoring the draw with everything closed. Bad switches, mis-adjusted switches can keep the alarm system in active mode.

Also, I would like to suggest a battery test. I know you said you had it tested, but try this. When you can get perhaps a full day with out driving the car, disconnect the battery cable when you get done driving the car. Measure the voltage. Let the battery sit and a day later measure the battery voltage again. A good battery will still be the same voltage. A battery with an internal short can still pass a current draw test when fully charged.

DennisMik

Did more searching and found this on the ECU-B fuse. It plays a part in the following circuits:
anti-theft, body computer, door locks, interior lights, headlights, instrument cluster, exterior lights, air conditioning, wiper/washer, navigation, power tops, memory, warning, power windows, supplemental restraints, trunk, tailgate, fuel door, cruise control, computer data lines, anti-lock brakes & mirrors.

Many of these circuits also have other fuses involved. As an examples of this:

Door 1 fuse is used in the following circuits:
anti-theft, door locks, interior lights, exterior lights, headlights, mirrors, wiper/washer, navigation, power tops, memory, warning, power windows, trunk, tailgate & fuel door.

Dome fuse:
warning, anti-theft, body computer, door locks, interior lights, headlights, instrument cluster, garage door opener & electronic suspension.


So try pulling the Door 1 and the Dome fuse and see if they make any difference.

One thing to keep in mind is that the above info is for my 2007 350. Lexus may have made changes between when your car was buil.and mine.