Bizarre Vsc Issue

[S Lewis]

I own a 1998 Lexus LS400 and have experienced an unusual issue with the car. When in cruise control, especially in a windy area, the VSC indicator will come on, along with the check engine light, and I will then lose the ability to accelerate. At that point, I must pull over. I have found that disconnecting the battery for a time and then reconnecting will reset the VSC, and the car will then drive normally. This nearly always occurs when in Cruise Control, but never during normal driving. Needless to say, I no longer use cruise control. Has anyone else experienced this issue? If so, do you have any diagnostic tips or suggestions to lead me in the right direction in terms of troubleshooting? Thank you in advance!

[wwest]

I own a 1998 Lexus LS400 and have experienced an unusual issue with the car. When in cruise control, especially in a windy area, the VSC indicator will come on, along with the check engine light, and I will then lose the ability to accelerate. At that point, I must pull over. I have found that disconnecting the battery for a time and then reconnecting will reset the VSC, and the car will then drive normally. This nearly always occurs when in Cruise Control, but never during normal driving. Needless to say, I no longer use cruise control. Has anyone else experienced this issue? If so, do you have any diagnostic tips or suggestions to lead me in the right direction in terms of troubleshooting? Thank you in advance!

If you get a CEL indication the VSC is disabled by default. Only a VSC indication alone should considered an actual VSC fault.

You don't say how many miles are on your '98. With enough wear it is possible that the cruise control cannot maintain a "set" speed due to the lack of engine torque. Use of non-premium fuel might rarely result in the CEL you are seeing.

Loosing the ability to accelerate, the engine management control system entering "limp" home mode, implies, clearly an engine fault, a serious engine fault.

I would have the stored codes read ASAP...!!!

[jasond86]

I own a 1998 Lexus LS400 and have experienced an unusual issue with the car. When in cruise control, especially in a windy area, the VSC indicator will come on, along with the check engine light, and I will then lose the ability to accelerate. At that point, I must pull over. I have found that disconnecting the battery for a time and then reconnecting will reset the VSC, and the car will then drive normally. This nearly always occurs when in Cruise Control, but never during normal driving. Needless to say, I no longer use cruise control. Has anyone else experienced this issue? If so, do you have any diagnostic tips or suggestions to lead me in the right direction in terms of troubleshooting? Thank you in advance!

i had a similar problem on my 98 ls400

go to autozone TODAY and have them read the error codes, you're currently damaging your engine further with every mile you drive. if it comes up as VVT error and several cylinders misfiring, you're in for a 1000 dollar trip to the mechanic to get your timing belt, spark plugs, and oil control valves and sensors. but after that everything will be running fine.

good luck

[oohryry]

The problem is your throttle body. I have the same year vehicle and had my codes read with the same exact problem. Your vehicle just hasn't gotten to the point that mine has. I have to run the air conditioner all the time to keep mine from happening. Everything is electronic, so when the vsc and check engine light comes on, it causes your gas pedal to go out. If this occurs while you are in traffic you can accelerate modestly if you press your foot on the gas pedal ALL THE WAY TO THE FLOOR to get you out of a situation or jam. I believe this is a very dangerous fail safe feature that Lexus has on the LS400. If you are on the highway travelling 65 miles an hour and this occurs, it could get a little shaky for an inexperienced driver. It runs around 1200.00 to replace the throttle body which Lexus recommends because they say it can't be cleaned. But we have people on this forum that have posted how to clean the throttle body, if you are inclined to do so. You may want to do a search of the topic. I don't believe I would have all of the tools necessary for the procedure so I didn't perform it myself. But one day when the economy is doing better hopefully I will spend the money to replace it. Hope this helps.

RyRy

ps: It will reset itself after you have turned your engine on and off about three or four times. The VSC and check engine light will come on at first then go out in about ten seconds after the third or fourth start. However, if you drive the vehicle while the VSC light is on you will not have vehicle stability control, which can be hazzard in wet weather. FYI

[wwest]

The problem is your throttle body. I have the same year vehicle and had my codes read with the same exact problem. Your vehicle just hasn't gotten to the point that mine has. I have to run the air conditioner all the time to keep mine from happening. Everything is electronic, so when the vsc and check engine light comes on, it causes your gas pedal to go out. If this occurs while you are in traffic you can accelerate modestly if you press your foot on the gas pedal ALL THE WAY TO THE FLOOR to get you out of a situation or jam. I believe this is a very dangerous fail safe feature that Lexus has on the LS400. If you are on the highway travelling 65 miles an hour and this occurs, it could get a little shaky for an inexperienced driver. It runs around 1200.00 to replace the throttle body which Lexus recommends because they say it can't be cleaned. But we have people on this forum that have posted how to clean the throttle body, if you are inclined to do so. You may want to do a search of the topic. I don't believe I would have all of the tools necessary for the procedure so I didn't perform it myself. But one day when the economy is doing better hopefully I will spend the money to replace it. Hope this helps.

RyRy

ps: It will reset itself after you have turned your engine on and off about three or four times. The VSC and check engine light will come on at first then go out in about ten seconds after the third or fourth start. However, if you drive the vehicle while the VSC light is on you will not have vehicle stability control, which can be hazzard in wet weather. FYI

Hmmmm...

Fact: Having the A/C "on" helps to prevent a CEL (and by default, a VSC code)..

FACT...it is RARE that the A/C compressor will run continuously, FULL TIME, with the A/C "on".

But....

The electric radiator cooling fans always run at high speed WHENEVER the A/C compressor clutch is engaged.

Conclusion: Your engines are over-heating, or threatening to overheat.

Until this moment I was puzzled as to why a "windy area" would have something to, would be pertinent, to the CEL and VSC.

Not if my theory, above, proves to be correct..

A "tail wind" or a "quartering tail wind" vs, say, no wind at all, or a head wind, might very well result in making it harder to keep the engine coolant within a reasonable temperatrue range.

Conclusion (#2): The engine direct driven radiator cooling fan's VC (Viscous Clutch), and/or the low speed mode of the electric radiator cooling fans, has/have failed.

Conclusion (#3): Some engine component/sensor has failed resulting in the engine operate in a non-optimal range wherein it is highly subject to marginal radiator cooling capability. The A/C operation provides just enough cooling "boost" to make a difference.

Throttle body can't be cleaned...BS, PURE BS, more dealer profit for/from installing new parts.

Probably cleans the old one in preparation for the next.....

[oohryry]

The problem is your throttle body. I have the same year vehicle and had my codes read with the same exact problem. Your vehicle just hasn't gotten to the point that mine has. I have to run the air conditioner all the time to keep mine from happening. Everything is electronic, so when the vsc and check engine light comes on, it causes your gas pedal to go out. If this occurs while you are in traffic you can accelerate modestly if you press your foot on the gas pedal ALL THE WAY TO THE FLOOR to get you out of a situation or jam. I believe this is a very dangerous fail safe feature that Lexus has on the LS400. If you are on the highway travelling 65 miles an hour and this occurs, it could get a little shaky for an inexperienced driver. It runs around 1200.00 to replace the throttle body which Lexus recommends because they say it can't be cleaned. But we have people on this forum that have posted how to clean the throttle body, if you are inclined to do so. You may want to do a search of the topic. I don't believe I would have all of the tools necessary for the procedure so I didn't perform it myself. But one day when the economy is doing better hopefully I will spend the money to replace it. Hope this helps.

RyRy

ps: It will reset itself after you have turned your engine on and off about three or four times. The VSC and check engine light will come on at first then go out in about ten seconds after the third or fourth start. However, if you drive the vehicle while the VSC light is on you will not have vehicle stability control, which can be hazzard in wet weather. FYI

Hmmmm...

Fact: Having the A/C "on" helps to prevent a CEL (and by default, a VSC code)..

FACT...it is RARE that the A/C compressor will run continuously, FULL TIME, with the A/C "on".

But....

The electric radiator cooling fans always run at high speed WHENEVER the A/C compressor clutch is engaged.

Conclusion: Your engines are over-heating, or threatening to overheat.

Until this moment I was puzzled as to why a "windy area" would have something to, would be pertinent, to the CEL and VSC.

Not if my theory, above, proves to be correct..

A "tail wind" or a "quartering tail wind" vs, say, no wind at all, or a head wind, might very well result in making it harder to keep the engine coolant within a reasonable temperatrue range.

Conclusion (#2): The engine direct driven radiator cooling fan's VC (Viscous Clutch), and/or the low speed mode of the electric radiator cooling fans, has/have failed.

Conclusion (#3): Some engine component/sensor has failed resulting in the engine operate in a non-optimal range wherein it is highly subject to marginal radiator cooling capability. The A/C operation provides just enough cooling "boost" to make a difference.

Throttle body can't be cleaned...BS, PURE BS, more dealer profit for/from installing new parts.

Probably cleans the old one in preparation for the next.....

lol, they probably do clean the old one. Some of the things you explain about the a/c I don't understand. I understand how the compressor works but what is a CEL? In my assumption, I figure since when the a/c is running the rpms rise somewhat and therefore do not give the throttle a chance to settle in it's lowest position. I have no hypothesis for my theory and it may not make any sense, but that's my theory. And is my engine really threatening to overheat. I've been running the a/c for the past couple of years now. I just make sure I add R-134 so it doesn't run out.

[wwest]

The problem is your throttle body. I have the same year vehicle and had my codes read with the same exact problem. Your vehicle just hasn't gotten to the point that mine has. I have to run the air conditioner all the time to keep mine from happening. Everything is electronic, so when the vsc and check engine light comes on, it causes your gas pedal to go out. If this occurs while you are in traffic you can accelerate modestly if you press your foot on the gas pedal ALL THE WAY TO THE FLOOR to get you out of a situation or jam. I believe this is a very dangerous fail safe feature that Lexus has on the LS400. If you are on the highway travelling 65 miles an hour and this occurs, it could get a little shaky for an inexperienced driver. It runs around 1200.00 to replace the throttle body which Lexus recommends because they say it can't be cleaned. But we have people on this forum that have posted how to clean the throttle body, if you are inclined to do so. You may want to do a search of the topic. I don't believe I would have all of the tools necessary for the procedure so I didn't perform it myself. But one day when the economy is doing better hopefully I will spend the money to replace it. Hope this helps.

RyRy

ps: It will reset itself after you have turned your engine on and off about three or four times. The VSC and check engine light will come on at first then go out in about ten seconds after the third or fourth start. However, if you drive the vehicle while the VSC light is on you will not have vehicle stability control, which can be hazzard in wet weather. FYI

Hmmmm...

Fact: Having the A/C "on" helps to prevent a CEL (and by default, a VSC code)..

FACT...it is RARE that the A/C compressor will run continuously, FULL TIME, with the A/C "on".

But....

The electric radiator cooling fans always run at high speed WHENEVER the A/C compressor clutch is engaged.

Conclusion: Your engines are over-heating, or threatening to overheat.

Until this moment I was puzzled as to why a "windy area" would have something to, would be pertinent, to the CEL and VSC.

Not if my theory, above, proves to be correct..

A "tail wind" or a "quartering tail wind" vs, say, no wind at all, or a head wind, might very well result in making it harder to keep the engine coolant within a reasonable temperatrue range.

Conclusion (#2): The engine direct driven radiator cooling fan's VC (Viscous Clutch), and/or the low speed mode of the electric radiator cooling fans, has/have failed.

Conclusion (#3): Some engine component/sensor has failed resulting in the engine operate in a non-optimal range wherein it is highly subject to marginal radiator cooling capability. The A/C operation provides just enough cooling "boost" to make a difference.

Throttle body can't be cleaned...BS, PURE BS, more dealer profit for/from installing new parts.

Probably cleans the old one in preparation for the next.....

lol, they probably do clean the old one. Some of the things you explain about the a/c I don't understand. I understand how the compressor works but what is a CEL? In my assumption, I figure since when the a/c is running the rpms rise somewhat and therefore do not give the throttle a chance to settle in it's lowest position. I have no hypothesis for my theory and it may not make any sense, but that's my theory. And is my engine really threatening to overheat. I've been running the a/c for the past couple of years now. I just make sure I add R-134 so it doesn't run out.

CEL, Check Engine Light.

Do you know, have you noticed, where the engine coolant temperature gauge normally sits..??

My '92 sits, always has, just a tad above the second mark.

If the engine management control system detects that the coolant temperature is above normal, or is rapidly rising but not yet "overheated", the electric fan will be switch on. Keep in mind that the engine coolant need not actually overheat in order for the system to "note" that the heating level is above "normal" or is rising too rapidly for overall conditions. If turning on the electric fan doesn't reverse the trend then the engine will be put in limp home mode.

And..., as a general rule for modern day cars the engine RPM does not rise to compensate for additional loads at idle. Even before, as, when the A/C compressor clutch is enaged the engine management system will open the DBW throttle, or idle air bypass, slightly, only as necesasary, in order to maintain the FIXED idle RPM with the additional load.

[S Lewis]

Thank you for all of your thoughtful responses! I am a bit alarmed, but also informed, and will check my codes at Autozone tomorrow, I will report back as to what those are. I may also clean the throttle body as a precautionary measure. I am somewhat confused about one thing - if a cooling issue or major engine malfunction were to blame, wouldn't I experience the issue during normal driving? To date, I have never experienced this issue when cruise control is not engaged - even in windy areas as I mentioned. It seems that only the cruise control triggers the issue. As for the question about the coolant temp, the temp reads slightly below the mid mark consistently. I have never experienced a higher temp reading, even during the summer. The car has 102,000 miles, by the way. Thanks again for all of the assistance so far! I will post back with the codes tomorrow.

Shaun

UPDATE: I had the codes checked with a reader today at Schucks. No codes were present or stored.... Any ideas?

[Parnellikitty]

I have a 1999 LS400 with 67,000 miles on it. I also am having the VSC Off light and the CEL come on at the same time, the Check VSC error message comes on and I my car dies. It does this when I let off of the gas, like when I am going around a corner or through an intersection. It is very scary. This happened one time last year and I called the dealership, the mechanic told me to make sure that my gas cap was on very tight. I tightened it and the problem went away. Now it has happened several times over the last few days and today when I was driving home my car quit 5 times. I have to pull over, stop the car, turn it off, then turn it back on, and put the gas to it right away to keep it running.

I called a local mechanic that replaced the brake sensors on my car a little over a week ago. He said that it was a problem with the transmission. That didn't make any sense to me at all, although I must admit I know very little about the mechanics/electronics of this (or any) car. I am a pretty quick study though and want to understand it before I take it in to either the dealership or another mechanic so that I don't get taken advantage of.

Per the suggestion, I will take the car over to a local AutoZone tomorrow.

I have two questions. 1. What is the cause of this problem? 2. Could the mechanic that replaced my serpentine belt and brake sensors last week have contributed to this problem?

Thanks so much for having this great forum.

[1990LS400]

An "Autozone" is the last place on earth I would take a Lexus to to solve a problem like this. You need a mechanic with experience with Lexus cars -- either a good indie or a Lexus dealer.

There are apparently multiple issues that can cause the problems you are experiencing. The only thing that has ever caused my 00 LS engine to die while driving and the VSC light to come on has been a bad battery - it has happened twice in the 60,000 miles I have driven this LS and each time a new battery solved the problem. I had a similar problem on a 90 LS I drove for 13 1/2 years. It could be another problem but, I'm curious, how old is your battery?

[wwest]

An "Autozone" is the last place on earth I would take a Lexus to to solve a problem like this. You need a mechanic with experience with Lexus cars -- either a good indie or a Lexus dealer.

There are apparently multiple issues that can cause the problems you are experiencing. The only thing that has ever caused my 00 LS engine to die while driving and the VSC light to come on has been a bad battery - it has happened twice in the 60,000 miles I have driven this LS and each time a new battery solved the problem. I had a similar problem on a 90 LS I drove for 13 1/2 years. It could be another problem but, I'm curious, how old is your battery?

You need a mechanic with experience with Lexus cars----.

May I revise that slightly....?

Mechanic implies "wrench" and that does not "fit" the process of troubleshooting these modern day cars, Lexus or no.

So the "proper" statement might have been....

You need a GOOD, HONEST, technician for troubleshooting...

Now that we have given you the easy part the hard part is up to you......FINDING ONE.

Ask around amongst your friends....

Oh, typically they do not "reside" at dealerships.

Oh, yet another thing...

Autozone isn't a bad place to start, knowing the codes will at least give you an edge up on the dishonest "mechanic" that tries to oversell the repair.

[Parnellikitty]

An "Autozone" is the last place on earth I would take a Lexus to solve a problem like this. You need a mechanic with experience with Lexus cars -- either a good indie or a Lexus dealer.

There are apparently multiple issues that can cause the problems you are experiencing. The only thing that has ever caused my 00 LS engine to die while driving and the VSC light to come on has been a bad battery - it has happened twice in the 60,000 miles I have driven this LS and each time a new battery solved the problem. I had a similar problem on a 90 LS I drove for 13 1/2 years. It could be another problem but, I'm curious, how old is your battery?

You need a mechanic with experience with Lexus cars----.

May I revise that slightly....?

Mechanic implies "wrench" and that does not "fit" the process of troubleshooting these modern day cars, Lexus or no.

So the "proper" statement might have been....

You need a GOOD, HONEST, technician for troubleshooting...

Now that we have given you the easy part the hard part is up to you......FINDING ONE.

Ask around amongst your friends....

Oh, typically they do not "reside" at dealerships.

Oh, yet another thing...

Autozone isn't a bad place to start, knowing the codes will at least give you an edge up on the dishonest "mechanic" that tries to oversell the repair.

I went to AutoZone this morning. The guy told me to hit the VSC Off button to turn the light off. It went off. He said, that should take care of the problem. I left and that took care of it.

I had tried to turn it off before when it went on, but it wouldn't go off. He said the same thing that you did that it was probably the battery. I just replaced the battery less than a year ago.

I don't understand if the battery is bad, why does it start the car right up?

Thank you for your reply. I know that I need to find a good Lexus technician.

Eva

[1990LS400]

I went to AutoZone this morning. The guy told me to hit the VSC Off button to turn the light off. It went off. He said, that should take care of the problem. I left and that took care of it.

There is a section in the owers manual for 98-00 LS400's on how to reset the VSC - I had to follow the procedure recently when I changed my battery. If the light went off, that is great but Autozone guy was apparently not familier with the process.

I had tried to turn it off before when it went on, but it wouldn't go off. He said the same thing that you did that it was probably the battery. I just replaced the battery less than a year ago.

I don't understand if the battery is bad, why does it start the car right up?

I've gone through a whole bunch of batteries in the 18 years I have been driving Lexus LS cars. Almost every time the first sign of failure has been the engine dying - most often when rounding a low speed curve or hitting a bump. My indie repair shop owner - a former Lexus service writer - thinks a connection between battery cells fails and gets temporarilly disconnected while driving. I too have almost always been able to restart the car and drive until the car dies again. Now when it happens, I don't bother to have the battery or electrical system checked but simply pop in a new battery.

Coincidentally, the last battery I replaced (an Interstate) also lasted only about one year. This time, I installed a battery from Walmart - they had several that fit but I got the largest dimension one with the most cranking power.

...I know that I need to find a good Lexus technician

Aside from what wwest said, Lexus dealers usually have lots of well trained, competent mechanics that have seen just about everything that can go wrong with Lexus vehicles -- something you are not going to find at an Autozone or other low budget garage. Look for an indie garage that specializes in Lexus and get to know the owner and mechanics. For me doing that has resulted in getting much better service and somewhat lower prices on repairs and maintenence.

Good luck!

[LS400Joe]

I went to AutoZone this morning. The guy told me to hit the VSC Off button to turn the light off. It went off. He said, that should take care of the problem. I left and that took care of it.

There is a section in the owers manual for 98-00 LS400's on how to reset the VSC - I had to follow the procedure recently when I changed my battery. If the light went off, that is great but Autozone guy was apparently not familier with the process.

I had tried to turn it off before when it went on, but it wouldn't go off. He said the same thing that you did that it was probably the battery. I just replaced the battery less than a year ago.

I don't understand if the battery is bad, why does it start the car right up?

I've gone through a whole bunch of batteries in the 18 years I have been driving Lexus LS cars. Almost every time the first sign of failure has been the engine dying - most often when rounding a low speed curve or hitting a bump. My indie repair shop owner - a former Lexus service writer - thinks a connection between battery cells fails and gets temporarilly disconnected while driving. I too have almost always been able to restart the car and drive until the car dies again. Now when it happens, I don't bother to have the battery or electrical system checked but simply pop in a new battery.

Coincidentally, the last battery I replaced (an Interstate) also lasted only about one year. This time, I installed a battery from Walmart - they had several that fit but I got the largest dimension one with the most cranking power.

...I know that I need to find a good Lexus technician

Aside from what wwest said, Lexus dealers usually have lots of well trained, competent mechanics that have seen just about everything that can go wrong with Lexus vehicles -- something you are not going to find at an Autozone or other low budget garage. Look for an indie garage that specializes in Lexus and get to know the owner and mechanics. For me doing that has resulted in getting much better service and somewhat lower prices on repairs and maintenence.

Good luck!

Hi I have a 98 LS400 with the same issue. Did you fix your issue? mine dies when i turn corners at low RPM's and then will start right up again. Any help would be appreciated.

Thanks, JoeLS400

Found my issue. When the Timing belt was changed, it was not put back together correctly. Apparently there is a timing Sprocket that is attahed to the crank. This sprocket has 34 teeth that register with the Crank sensor. When the car was idleing, the sprocket would wobble out of range of the sensor. When the car had RPM's of over 1000, the sprocket would suck into place. I took the car to the Dealer and they were able to diagnose the issue. This is what I get for taking it to a cheap garage for the timing belt replacement. The Fix was labor to tear down the front of the motor and tighten the sprocket in place. $600 and some change. I hope this helps.

LS400Joe