This very likely pertains to many LS430 owners:

While replacing the front exhaust Y-pipe (many threads on this, a common defect on the LS430), I discovered buried on the driver's underside, a braided wire that is broken due to the proximity just a couple inches above the hot catalytic converter. The wire appears to be a special ground from a transmission-to-engine bolt and a dedicated ground bolt on the body. (Lexus body parts are all dipped in paint, and a ground wire must be connected to metal, not paint, hence the dedicated grounding bolt to metal.) Anyway, I didn't find any thread on CL about this fried ground wire, and I have to believe that ground wire is fried and broken on many other LS430s. I bought new braided ground wire, and will repair it, but I'm going to attach it to a different bolt on the transmission, slightly away from the hot catalytic converter.

While I have no known electrical or transmission issues on this or any of my other LS430s, a broken ground wire on this vehicle is not something to ignore. I plan on checking this ground wire on my other LS430s as well.

Tom

 

Toyota typically has 4+ grounds on their engines/trans to the body, so 1 less ground typically would not affect anything.

 

Actually, according to a Lexus master tech and a LS430 schematic, there is only one (1) braided ground wire for the transmission, and one (1) braided ground wire for the engine, each attached to the body. The engine and transmission are mated, so technically only one ground wire is required for both. Having two ground wires provides redundancy. However, with one fried ground wire, the engine and transmission both rely on the one remaining old ground wire, without redundancy. It's a 1/2" wide 10 gauge AWG braided ground wire, designed to handle over 50 amps, not insignificant. When I find something on my 430s that is broken, I fix it. This is too easy ... and inexpensive to replace, especially while replacing the Y-pipe.

 

Do you have any images?

Following is a post you may find useful:

https://www.clublexus.com/forums/ls-...ng-issues.html

 

I noticed this when I did my Y pipe and posted here:
https://www.clublexus.com/forums/ls-...this-wire.html

I didn't get many responses so thanks for clarifying what it is. I didn't know it went to the transmission on the other end but I thought it might. Anyway, I did not do anything about it and I've had no issues so far.

 

I'm glad this thread came up I thought mine was burned in half from high current and was abnormally damaged. I replaced mine when I saw it burned, but not with the OEM ground strap but a longer heavy gauge wire that's further from the heat.

 

Thanks, yes, I'm aware of electrical and grounding issues with the LS, back to the original LS400 I drove. The pics in heartygrn's thread (link below) show the fried braided ground wire.

 

Your thread is spot on ... I searched and didn't come up with your thread. It is the braided ground wire in your pics. As posted above, you may want to replace it with an 8" long by 1/2" wide braided ground wire with 1/4" ring on each end. Connect one end to the grounded post (in your pic) and the other end to a transmission pan bolt. That's what I did even though I have no issues now. As these cars age, the ground wires age as well. A new ground offers peace of mind that the engine and transmission ground is redundant.

 

It burned due to its close proximity to the intense heat of the catalytic converter. Like you, I replaced it and moved the location of the ground wire to a different bolt on the trans, away from the catalytic converter.

 

Last time when I was working on center shaft giubo and central bearing, I also noticed the braided ground cable between transmission and body is half burnt due to proximity of catalytic converter. Also one of the bolt looked rusty.

Will you recommend the specific brand of the new cable, and if you can also suggest the length of it? Thanks in advance.

Yodaone, I read your topic about grounding issues in Ls400. I should say it’s a very material and I saw lots of research was put into it. I haven’t had prior experience with fixing ground cables and battery negative wire, but have you noticed any difference after you fixed this issue in your car?

 

Use 4 gauge insulated battery wire to ground at two points engine to body, trans to body, and any existing body to body grounds. That's what I have done for about 12 custom engine cars and a few times when I've had complete drivelines out of cars and noticed worn straps

 

No before/after voltage drop measurements taken, but suspect improvement...
Improved tin-plated fine-strand marine grade wire is more flexible, 4 gauge vs 6...
I replaced my LS400 100A alternator with a an LS430 130A.
In preparation, replaced my Positive alternator cable with 4 gauge.

One thing I do not like about the A650-E transmission (1998-2000 LS400, 2001-2003 LS430) is single wire/solenoid scheme that relies upon a series of ground paths...

Numerous posts on the LS400 relating to notchy low speed down shifting.... I do not see this issue on the LS430 forum (or perhaps haven't noticed)

Probably increased voltage drop here vs other areas...and that is not factoring in resistance of solenoid wiring bathing in 200F transmission fluid.

The LS400 did not employ a separate grounding wire/strap on the A650-E transmission, yet Toyota employed it on the LS430.

Will add a ground wire to the LS400 transmission to see if improved shifting.

 

Look again it's def there.
Google- "LS430 transmission SIA Electronics"

 

SIA Electronics fixes whatever is ailing the ECU module when the car is exhibiting a harsh 2-1 downshift. It doesn't have anything to do with the ground wire...

 

Cool
Tell YODA that...