I've found serveral places in the owners manual about steps that have to be taken if the 12V battery is disconnectd/reconnected. The automatic rear door, the power windows and the moonroof all may need to be initialized. But then I found another section in the manual that says the "idle speed" may also need to be initialzied after a 12V battery disconnection.

TSIB EG010-05 describes the process a tech can perform to complete the initialization. I guess my question is...how "likely" is it that I'm going to have to do this if I disconnect the battery? Clearly, this is something that I'm not going to be able to do myself, since it requires some sort of diagnostic test set to get into the necessary modes.

My other question is if anyone knows any other potential pitfalls to disconnecting the battery that I've missed? The last thing I want to do is turn my RX into so much immobile junk just by disconnecting the battery.

 

i wouldn't disconnect the battery from a RX400h...it is a hybrid so I don't know what the repercussions might be. If you need to take it off then get it done at the Lexus dealer, just incase anything goes wrong...they will have to fix it....heh

 

Well, the reason I might have to disconnect the battery is that I will be installing an aftermarket stereo. If I can get away without disconnecting the battery, I will...depends how much work needs to get done to the wiring harness I guess. If it comes to that, I guess I'll end up having to pay an hour of labor to the local Lexus dealer to implement the TISB. I could try & act like I didn't know what happened, but I don't think I'll get too far with that when they see the aftermarket radio in the dash

 

there will be no repercussions when disconnecting the baterry. its just like any other vehicle in that regard. JUST DON'T TOUCH THE ORANGE WIRES!!!!

 

This seems hokey on the battery not being able to be disconnected. I must disconnect that Optima in my RX300 several times a month. Unless it is something related to the hybrid system that I really doubt (since you mentioned things that need to be initialized that don't run with the hyrbrid system) and I don't see what the issue would be other than your transmission resets your driving pattern and you will probably lose presets.

 

Yes. according to the owners manual, in addition to having to re-calibate the automatic rear door, power windows and moonroof, the proper interaction between the gasoline engine and the hybrid motor may be affected if the battery is disconnected. I've seen the related service bullietin, and while the other adjustments can be done at home, the hybrid adjustment apparently needs some special Lexus diagnostic gear to complete.

Lucikly, I was able to complete the HU replacement without disconnecting the battery, so I was not impacted by this issue.