ls400beave

Today when I started my 1998 LS400 suddenly the rpm went to 2000 rev (without A/C or light on)and the VSC alarm red lamp lighted and on the menu screen it was showing "Check VSC" and "Check Engine" respectively and on the left side the VSC orange indicator was showing "VSC off" also the accelerator was not working !! after all this I switched the car off and re start it again, and everything was normal but with the service engine and VSC light on. I unhooked battery and reset everything and no service engine or VSC light is on and the car is perfect. What would cause this? this is the 2nd time it had done that in 3 weeks.??

Kansas

Causes are either a defective TPS (throttle position sensor) or PPS (pedal position sensor) - failure can cause the accelerator pedal to become inoperable and the CEL and Check VSC warnings. There are detailed diagnostic procedures for determining which is the cause of the problem. I forgot which was completely gone on my 2000 LS400 but I replaced both sensors since the other was marginal. Don't put off getting this fixed. The problem on my LS was intermittent for a few days before I just barely limped it in to a repair shop.

Edit: Here is a thread where I postsed instructions on how to test the PPS and TPS: https://www.clublexus.com/forums/ls4...rror-code.html

ls400beave

Thank you very much. That was very helpful!

whit3b0y

mine kept doing this last winter.... took alot of trouble shooting. The power wire for my amp was resting on the pedal position sensor pushing it down. bent it up a bit. havent seen VSC in a year!

ls400beave

Thanks Whit3bOy. I do not have a Amp hooked up so I do not think that would be the issue. So I called the Lexus dealership this morning and they told me that on my 98 there is two TPS sensors. One is the fuel Injection (TPS) and the other is the traction control (TPS). Unfortuantly, I reset the battery so I erased the code (duh!!). He believes it would be more then likely the traction control one rather then the fuel injection one sense the VSC light is coming on. However, it still could be the PPS. I am frustrated that I reset the battery... I just want to get it fixed. If anyone has expierenced this problem let me know.

ls400beave

One last thing. Do you think the Lexus dealer could have refered to the PPS as one of the TPS he told me there was?

ls400beave

Sorry. So my 98 is different from the 99 and 00. The 98 has two TPS, the 99 and 00 only have one. Just figured that out...

Kansas

I'm curious. Where did you get that information?

Cope

I have this exact situation yesterday. Initially car went into limp mode as you say. I turned it off for 5 min. Started ight up. Both VSC & CEL stayed on but car ran fine. After reading this thread I decided to take into the shop this morning. When i started the car up both lights went out. I drove around for awhile stopping and shuting it off and starting up. Everything is fine. I took it to the shop anyway to have checked out. After hooking it up to computer no codes showed up a failure. I am sure it will fail again, but I do not want to replace both throttle sensors that are mention just guessing. Of course on the other hand I do not want to get stranded on a trip. I have a trip to Atlanta in 10 days. Not sure what to do. My mech. said he would rather not just throw a couple parts at it and hope for the best. Any ideas on which direction I should go... Thanks... 1998 LS400 with 141,000 miles

McPierson

iTrader: (3)

I like your mechanic. No suggestions however. This is the biggest reason people want new cars. Trust issues.

GS4_Fiend

iTrader: (22)

check for codes first and we can start from there.

Kansas

My recommendation is to have your mechanic perform the diagnostic tests on both the TPS and PPS per the detailed procedures in the shop manual for your car. If your mechanic does not have access to these procedures, then I think you should get another mechanic who does.

Cope

I appreciate all your responces. I am taking the car back today to my mechanic. He thinks he can resolve my problem. I have printed out all threads I could find on this problem to take with me. The knowledge all of you have on these cars is priceless. I will post his findings. Thanks guys

Cope

Turned out to be PPS. Thanks to all for this thread. For someone like me that has little mechnical knowledge it is good to have an idea what the problem is before I take it a shop. Helps to know if the mech. is shooting you a straight repair job and fair price