1999 Ls 400 Check Engine And Vsc Lights Come On?

[Badams]

While stopped at a stop light this evening the Check Engine and Check VSC lights came on. I pressed the VSC button multiple times but the condition did not change. When the light turned green the engine was still running but the car would not accelerate beyond idle speed (RPM's stayed at about 1200). I was not far from where I was going to dinner so I parked and went in for dinner for about an hour. Came back out and started the car and both lights were on again for a few minutes. I drove home about 20 miles on the highway with no problems. Got back down to city diving speeds with turns and stop signs and the lights both came on again. The car is unquestionably still running at all times it is turned on but unless the accelerator pedal is floored the car does not run much above idle rpm speeds. A friend who knows cars told me it sounded like a throttle postion sensor :-? Any ideas or information about the problem and how to get it taken care of would be greatly appreciated.

Thanks in advance for your assistance.

[jcrome04]

Sometimes when the ECU thinks something is wrong, it will restrict the engine to certain specs, like not having a certain amount of power, and not going over a certain RPM, to not damage the engine.

I don't know what could be the problem but I'd say get the codes checked ASAP!!

[Leadfoot]

The car is unquestionably still running at all times it is turned on but unless the accelerator pedal is floored the car does not run much above idle rpm speeds. A friend who knows cars told me it sounded like a throttle postion sensor :-?

Your car is in what is called "limp mode", and a malfunction has occurred in the electronic throttle system. It is a very clever system that determines how much power you want using the accelerator position sensor and evaluates the vehicle conditions (speed etc) to determine what position to put the electrically powered throttle valve (which has a position sensor of its own!). This complicated system of sensors, motors and clutches means the '98 and up are very smooth, but with added complication.

So the first thing you need to do is "limp" to someone who can read the onboard diagnostics info (you have an OBD2 system) and report back the fault codes. The most common fault I have seen people here having is with the position sensors.

The reason the VSC is showing a fault is due to the fact that the skid control is integrally linked to the throttle control system, since you have a fault the car will not be able "back off" the throttle and save your a$$ if you get it too far sideways!!

[Badams]

Thanks for the information. I am able to borrow the diagnostics handheld computer. Where is the hookup in the car located to hook the diagnostics reader to?

[Leadfoot]

Thanks for the information. I am able to borrow the diagnostics handheld computer. Where is the hookup in the car located to hook the diagnostics reader to?

its under a little cap in the drivers footwell kickpanel, under the steering column.

[Badams]

Dealer now has the car and says the throttle body needs replacement. What should I expect to pay for that :-?

[92silverls400]

Dealer now has the car and says the throttle body needs replacement. What should I expect to pay for that :-?

expect to pay about $1200 to $1300 from the lexus dealership. I had the same problem, lucky me, I had purchased extended warranty for my 2000 Ls 400. Replaced throttle body unit.

[Leadfoot]

Dealer now has the car and says the throttle body needs replacement. What should I expect to pay for that :-?

Really? The throttle body needs replacing? What was the fault codes they read? It seems very strange, if by throttle body they mean the whole assembly. Can you ask them if its the entire assembly that needs replacing, if that's what they are proposing. It could be that the parts are only available as an assembly, much like the solenoid screen on the power steering where you have to buy the whole thing to replace a small part. Will be interested to find out what their diagnosis came up with, as I would think the throttle valve motor would be the first part to give out. I sure hope this isn't common.

Just so we are speaking the same lingo please find attached the exploded parts diagram.

Thanks for the update.

.

Throttle_body_components.pdf