JudyAA Posted October 21, 2013 Share Posted October 21, 2013 After months of parasitic battery drain, I was told by my mechanic, a former Lexus mechanic, that the multiplex body control module is what's causing the drain. The car has 157K miles and I hadn't planned on doing another repair before selling it. Where is this part located, what labor has to be done to replace it, and is it possible to get a refurbished one that will work with my existing key? My mechanic says it's possible this is related to an accident in which the headlight was replaced, so the case is being reopened with the insurance company. Since the servo motor is also going bad, should I just trade in the car? Quote Link to comment Share on other sites More sharing options...
lenore Posted October 21, 2013 Share Posted October 21, 2013 Here is part on Ebay: http://www.ebay.com/itm/Lexus-RX-330-04-06-Multiplex-Network-Door-Computer-Unit-Module-89222-0E012-A353-/331027445556?pt=Motors_Car_Truck_Parts_Accessories&hash=item4d12c5f734&vxp=mtr Probably not that difficult to replace (under 1 hour) Heck fix it and keep car...... Quote Link to comment Share on other sites More sharing options...
10rx350 Posted June 19, 2015 Share Posted June 19, 2015 I just had my bumper replaced and now I am experiencing battery drain issues. I am curious if this might be somewhat related? Quote Link to comment Share on other sites More sharing options...
HeenaM Posted February 2, 2020 Share Posted February 2, 2020 We've got the same problem with our 2008 IS250. The battery and alternator are fine, so we had an electric specialist come and have a look. We learned that there's a parasitic drain from the onboard body control module which is discharging the vehicle when it's switched off. The body control module also powers the audio module which is another item that can sometimes have this parasitic drain problem. Either way it needs repairing or replacing and 'regular' garages don't seem to have the software or coding skills needed to fix it. So it will have to go to Lexus & that's going to cost a lot! 😞 Has anyone managed to remedy the problem? If so, how and how much did it cost? Quote Link to comment Share on other sites More sharing options...
JudyAA Posted February 2, 2020 Author Share Posted February 2, 2020 I should have posted the final resolution to the repair while I still owned the 2004 Lexus. I took it to the dealership and they admitted that they were scratching their heads trying to identify the source of the parasitic battery drain. They eventually identified it. It was the driver seat lumbar support! I opted to have it disconnected rather than fixing it, and that took care of the problem. Quote Link to comment Share on other sites More sharing options...
HeenaM Posted February 6, 2020 Share Posted February 6, 2020 I didn't know that lumbar support would cause a drain. Isn't it 'just padding'? --- We had the car about 4 years and it wasn't an issue before. The drain was so 'strong' that a new battery was reduced to 43% of its life within 2 months. Not using the car for a day or more resulted in the battery being so flat that we couldn't even lock the car with the button on the key, but had to do so manually. We have now sold the car. We got less for it because we declared the fault but that's only fair. 🙂 Quote Link to comment Share on other sites More sharing options...
RX400h Posted February 10, 2020 Share Posted February 10, 2020 Most likely, the lumbar support is an inflatable bladder that requires compressed air from a compressor. It could be that the compressor had shorted, causing the drain. Quote Link to comment Share on other sites More sharing options...
HeenaM Posted February 11, 2020 Share Posted February 11, 2020 Our drain wasn't caused by the lumbar support. The diagnostic report showed there was a parasitic drain from the onboard body control module which was discharging the vehicle when it's switched off. Alternatively, it could have been the body control module also powers the audio module which is another item that can sometimes have this parasitic drain problem. Quote Link to comment Share on other sites More sharing options...
Danee Day Posted January 17, 2022 Share Posted January 17, 2022 On 2/6/2020 at 5:29 AM, HeenaM said: I didn't know that lumbar support would cause a drain. Isn't it 'just padding'? --- We had the car about 4 years and it wasn't an issue before. The drain was so 'strong' that a new battery was reduced to 43% of its life within 2 months. Not using the car for a day or more resulted in the battery being so flat that we couldn't even lock the car with the button on the key, but had to do so manually. We have now sold the car. We got less for it because we declared the fault but that's only fair. 🙂 The lumbar support in my Lexus RX 300 is mechanical, and not just padding. It is a button control on the driver's side with the electronic seat settings, and it mechanically inflates and deflates lumbar support mechanism, accordingly. It can be adjusted very "flatly" or comes out, up to about 2-3 inches, for firmer lumbar support, if desired. Quote Link to comment Share on other sites More sharing options...
RX400h Posted January 22, 2022 Share Posted January 22, 2022 I would call that "electro-mechanical" because electricity is required. 😏 Quote Link to comment Share on other sites More sharing options...
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