Hello,

I have an 02 Ls430. I unbolted a ground wire on the passenger side and don’t remember where it’s supposed to go. I bolted it back into one of them, but I’m not sure if I have the right one. Kinda embarrassed I have to ask, but just wanted to see if anybody knew. There’s two holes next to each other, so it’s hard to know which one. Any help would be appreciated. Thanks!

 

I can't quite tell from the photo, but if the two metal objects containing the red circles (the one with "R" next to it, and the aluminum housing in the background) are in direct physical contact with each other both would be at the same electrical ground and it does not matter which one you use.

 

Your connection above is correct and it does matter.
As is explained here, it is important not to connect the ground wire directly to the aluminum engine block to avoid the galvanic corrosion. Toyota/Lexus seldom connects the ground wire to the engine block directly because the copper and the aluminum causes the galvanic reaction and the contact point will be corroded as time goes on. Instead, they use another material in between them as is shown in these photos.

The photo below is from a JDM Toyota Sienta which shows another example of how the ground wire is connected. The red arrow shows the ground wire from the battery and the blue arrow shows the grounding point to the engine mount. To avoid the galvanic corrosion, they dare use the steel part of the engine mount. This increases the resistance some but Toyota considers that it is more important to avoid the galvanic corrosion. As is shown here in the chart, the steel's voltage is higher than the aluminum alloy and lower than the copper alloy. Thus the corrosion seldom occurs.

 

Awesome, thank y’all so much. I figured it was that one, but just wanted to make sure!