Agreed. I like to keep those areas clean in all the cars I've had. The one I bought wasn't bad, but it was squeaky clean once I got a hold of it!

 

Also, there are drains in the bottom of the body panels, make sure those drains are free and clear of debris

 

Agreed. This is my only complaint with my LS430, which usually lives outside and under a couple of trees. For some reason the channels in the trunk (as well as the humongous hood cowl now that you mention it!), seem to attract a huge amount of stuff. I try to clean them out regularly; as you say, if gunk builds up in those side channels -- often right near where the strut attaches -- rainwater can easily overflow into the trunk. Never really had this with other cars, so I'm not sure what's up.

 

I get it, this is an old thread. But I have a 2003 LS430, that has simliar symptom's as Misstootie1, and this thread is helping me with a sense of direction on how to address this. All of y'all's posts have helped once again.

 

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I Hope this helps you, as we found the problem and have fixed it temporarily, and will permanently fix it once the parts come in.

First off, my taillights were leaking, for several reasons; the taillight "gasket" was all "wompity" and water was getting in there, where I suspected. Bought the "packing" (Lexus calls it) for both taillights. The driver's side harness plug was a little corroded, so cleaned that up. The passenger side, though...yikes! This was a known problem of the previous owner who attempted to fix it himself, did a (really) ha-harted attempt, gave up, and got rid of the car. Anyway, the mini light on top, the connector was melted and blackened. The connector to the harness was all green inside. The taillight had about a cup of water inside. All this was causing the crazy electrical problems. I ordered a new harness for the lights, and once that comes in I will install it.
My husband decided to add permatex to the edge of both sides of the gasket (packing) to make sure no water gets in that way again. Also noticed on the driver's side, the black trim against the taillight where the trunk meets the tailight...that black hard plastic trim has come away from the body creating a crack where the rain was able to get in. So fixing that, as well. For now, with silicone. I will fix it permanently by replacing the metal pins that apparently broke off.

All in all: I do not have any leaks from the sunroof drain, but I'm still going to floss it with the weed eater wire.

The fuse junction box in the back on the driver's side? Bought a used one from a junkyard for nothing. There is nothing wrong with mine. All those bizarre problems were from leaking taillights and water getting into that harness and creating havok! All is well now, the car works as it did.

I will post an update with parts numbers and where to look for anyone's future reference.

Hope this helps someone!

 

I don't want to hijack this wonderful thread.
I have used the information here to start my troubleshooting... I found my trunk: including both wheel wells and all items in it, dry and dusty. No evidence of ever having water in the trunk... seems my adventure may be just getting started. Thanks y'all. From here, a new thread may be coming.

 

same happened to me, it was just the water getting into the rear j/b, got a used one for $100
https://www.clublexus.com/forums/ls-...al-issues.html

 

if your symptoms are similar to OP then you for sure need a new trunk fuse box

sometimes its dry in there but if any water gets in from taillights it will stay in the fuse box and kill it slowly

 

Okay, taking advice and buying Lexus 82670-50073 Block Assy, Luggage Room Junction (thanks for the part numbers Miss Tootie1)

 

Good News, 82670-50073 Block Assy came in on Thursday and was installed on Thursday. Bought a battery charger on Thursday, disconnected the new dead battery and begun charging it. New Alternator came in this afternoon (due to a parasitic draw, that killed a 2 week old battery), installed alternator today. Reconnected battery and the LS fired right up after sitting for 2 weeks. For about 45 minutes had a bumping sound coming from the top back of the engine. I had to check to see if something was interfering with the fan, nothing was. Drove around the block then filled the gas tank (bumping sound was still present). Hmmmm?
Also, I have no fuel gauge or 'miles till empty' on my dash. Anyone got any ideas on how to address:
1. The bumping from top back?
2. No fuel gauge or miles to empty? I wonder if this has to do with the Trunk block assembly?
Any help is appreciated.

 

Gosh. Have no idea here. My truck block assembly wasn't the problem when my fuel gauge or miles to empty stopped working (amongst all the other dash gauges/lights. Mine was due to rain water leaking from the taillights and getting into the taillight pigtail harness. Best of luck to you...hope you find it soon. Before I knew what was causing it, I looked up all the things the trunk block assembly ran, and it wasn't the things going wrong in my car. But with electrical problems you never know, so I bought one anyway. Found out my instincts were right; it wasn't that box after all.