Hi there,

I just purchased an 2004 LS430 today with 240k miles on it. The previous owner was getting rid of it because they had an incident when they were sitting at a stop light and the vehicle started jerking and accelerating on its own. I had the car towed to my place and I have not been able to recreate the issue they faced.

I was wondering if anyone has any idea of what happened there and where would be the best place to start troubleshooting? From my limited knowledge I want to say this might be an ECU issue and I'm tempted to just send it to SIA to see what will happen. I am getting service codes read hopefully soon and maybe that will give me a better idea.

Any help is greatly appreciated!

Thanks

 

https://www.clublexus.com/forums/ls-...-my-car-5.html
Read that tale of woe before you knee jerk ship your ECU to SIA.

The 2004 models did have a transmission software fix. You might investigate whether your car had this done at the dealer. That may or may not be part of what caused the previous jerking symptoms.

 

In all fairness, both SIA and Tanin told fanboy replacing the caps in his ECU was unnecessary. From what we know SIA eventually agreed to do the work.
Just yesterday fanboy reported he received a replacement ECU from Tanin and his car still does not start. It would seem there is more to this story....

 

I would do nothing unless it happens again. one time un explained occurrance no reason to throw money at a maybe problem.
if you get service history you will know what 1st owner had done while he owned it. would have transmission fix in the record
that milage should have multiple timing belts and spark plug changes so you need to find out that at least.
I would start running premium gas, maybe coolant change, some easy stuff to get more familiar with it.
transmission is among best ever made and almost bulletproof but might need fluid exchange or drain and fill but both of those are best left to good mechanic.
everything on that car is over engineered to last 20-30 years or more, a true road warrior.

 

Yeah I think I'm going to hold off on the ECU for now. Thanks for the info!

 

Yeah my plan is to take it to Lexus for a general inspection and see what they have to say. Maybe they can do the software fix that TominPT was mentioning. Part of me also thinks that the previous owner was embellishing the story they told me, I cant say for sure that it wasn't user error or a stuck floor mat or something causing the acceleration. Could just be a very rare experience.

 

You'd be surprised how many times something like this happens and it was actually because the driver accidentally had their foot on both the gas and the brake at the same time. Traction control will kick in to stop wheel spin which causes the jerking while trying to accelerate against the brakes. I've had that happen when I accidentally left the traction control on while trying to do a burnout at drag racing events in a previous car. The result was pretty much exactly what you said the previous owner described. Maybe this wasn't the case with the previous owner or maybe it was. Definitely a good idea to wait and see if it does it again.

 

I had exactly that happen on Friday night and it was the floor mat that had moved and was pressing on the throttle pedal when I had my size 16 foot on the brake pedal.
It behaved so strangely that I pulled over to check and immediately saw that the mat had moved and was snagged on the throttle.
Unfortunately, the metal eyelets were torn out of the drivers side carpet when I bought the car so the mat does move around. :-(

 

You may have done this already, but the LS430 has too many electronic components and these interact way too much with the ECU. Just to “check the box”, test the battery and if needed start fresh with a new one. If the battery appears solid, disconnect it for several minutes and reattach to “boot” everything in the car. Expect some strange side effects (like the map guide defaulting to a different region, A/C system strange noises, etc.) but allow a day or two to smooth out.

Hope all your symptoms and worries are resolved.