I have a 2006 Toyota Highlander Hybrid, all wheel drive, with 53,000 miles. Two months ago I had the tires rotated (all tires are the same size and age) and the engine battery replaced. Immediately afterward I started experiencing intermittent VSC alarms. When this happens the brakes become mushy and I believe that only the rear brakes are operating. To get rid of the alarm I simply turn the engine off for 15 seconds and restart.

Of course I took it to the dealer and they said the VSC computer had to be replaced ($1940). I didn't have the money, so I kept driving the car. Now I realize that the problem is associated with how I use the brake pedal. If I release the brake pedal with a swift motion (you hear the pedal pop back up), I don't have the problem. If I slowly release the brake pedal or have the car slide forward with my foot on the brake, I get the alarm.

I took it to a second dealer (the mechanic was a friend of a friend) and he also tried to adjust the problem with no success. After driving the car with this problem for two months, I've stopped getting the VSC alarm except possibly once every couple of weeks.

This seems to be more of a sensor problem to me than a computer problem. Any suggestions?

Thanks, Bill

 

The VSC probably needed to be reinitialized when the 12 volt battery was replaced.

 

Hi WWEST,
I have seen your many posts and realize how knowledgable you are about many car problems. However, in this case the problem is just not that simple. I just posted the note below on NHTSA/ODI Safety Complaint database.

This input will show the commonality between Complaints #10139802, 10194711, 10251646, 10256617, 10259470, 10280157, & 10289084 which are for multiple Toyota/Lexus models. All these complaints say same thing in different words. Problem is a VSC alarm which sets off indicators for Skid, ABS, and other systems with the ECU computer causing an audible alarm and message to check VSC system. Alarm seems to partially disable braking system. Brakes become mushy and I believe front brakes are disabled. I know rear brakes still operate mechanically, and because ABS is disabled, rear brakes can lock up and skid if brake pedal is pushed hard enough. Standard response from Toyota/Lexus is to replace ECU computer. However, as you can see from above complaints, this does not always solve the problem.
My own complaint is for my 2006 Toyota Highlander Hybrid 4WD-i with approximately 54,000 miles. I experienced a one time VSC alarm over 1 year ago when the engine start battery was dying. Toyota dealer told me to replace battery and see if problem continued. I replaced battery and also had all four tires rotated. Immediately after I started experiencing more VSC alarms at a higher rate. This has occurred while driving on highway as well as at low speed. It has also occurred both with and without applying the brake. 2 different Toyota dealers have attempted to "adjust" system to stop alarms without success. I have gone as long as 4 months without an alarm and then for no reason (no skid event) alarm reoccurs. Solution both dealers have now given is to replace ECU. Due to finances, I can not afford new computer, so I had a Toyota mechanic with 25 years experience install two different used computers with neither one solving problem. After examining the internet and your complaint board I now realize that this problem occurs across Toyota's product line and that there is no clear solution. I believe Toyota is aware of the problem and is not acknowledging that they have an ECU computer problem.

 

If you do some research you will find that this exact same VSC situation occurs in multiple Toyota/Lexus products. I just input the following item to the NHTSA/ODI of Safety Complaint System.

This input will show the commonality between Complaints #10139802, 10194711, 10251646, 10256617, 10259470, 10280157, & 10289084 which are for multiple Toyota/Lexus models. All these complaints say same thing in different words. Problem is a VSC alarm which sets off indicators for Skid, ABS, and other systems with the ECU computer causing an audible alarm and message to check VSC system. Alarm seems to partially disable braking system. Brakes become mushy and I believe front brakes are disabled. I know rear brakes still operate mechanically, and because ABS is disabled, rear brakes can lock up and skid if brake pedal is pushed hard enough. Standard response from Toyota/Lexus is to replace ECU computer. However, as you can see from above complaints, this does not always solve the problem.
My own complaint is for my 2006 Toyota Highlander Hybrid 4WD-i with approximately 54,000 miles. I experienced a one time VSC alarm over 1 year ago when the engine start battery was dying. Toyota dealer told me to replace battery and see if problem continued. I replaced battery and also had all four tires rotated. Immediately after I started experiencing more VSC alarms at a higher rate. This has occurred while driving on highway as well as at low speed. It has also occurred both with and without applying the brake. 2 different Toyota dealers have attempted to "adjust" system to stop alarms without success. I have gone as long as 4 months without an alarm and then for no reason (no skid event) alarm reoccurs. Solution both dealers have now given is to replace ECU. Due to finances, I can not afford new computer, so I had a Toyota mechanic with 25 years experience install two different used computers with neither one solving problem. After examining the internet and your complaint board I now realize that this problem occurs across Toyota's product line and that there is no clear solution. I believe Toyota is aware of the problem and is not acknowledging that they have an ECU computer problem.

 

"..If I release the brake pedal with a swift motion.."

There is a pressure sensor somehwere in the braking system to sense brake fluid pressure. I would "shotgun" (pure guess) replace that sensor.

You should also check to be sure your brake lights turn off, and on, in the proper way/point/time. Quick release would be more likely to turn them off if the microswitch is slight out of adjustment.

 

WWEST,
Good suggestions; I'll try them the next time it alarms. I drove up in the mountains (approximately 7000 foot altitude) and the alarm was on for the entire 10 days I was up there. I came back down the mountain and the alarm went away. That sounds like some kind of pressure sensor to me.
As soon as it comes back (and it will), I'll check the brakes and the microswitch suggestion. In the meanwhile I'll try and find the pressure sensor.
I read somewhere else on the internet that there's a small auxiliary motor (similar to the windshield wiper motor) used to increase pressure in the system when you apply the brakes. What I read said that if you had a bad battery, the low voltage partially damages the motor/pump and that can give you a low pressure indication that causes the alarm.
I'm a computer guy, not a car guy. These symptoms just don't act like a computer problem or glitch. Either the firmware in the computer is detecting a problem when there really isn't a problem, or a sensor somewhere is bad, or the pressure really is low because of the motor/pump, but the brake fluid itself is full. I'm really frustrated with Toyota because they won't try and do anything without replacing the ECU first. I don't have $2000 to give them while they try and shotgun the problem.

Thanks, Bill

 

The ABS pumpmotor, the system that provides additional brake fluid pressure, will typically go off-line if the battery voltage is low.

 

The brake pedal stroke sensor is mounted on the brake pedal arm and changes voltage based on the position of the brake pedal. This sensor provides a proportional voltage output based on brake pedal position.

This is only interesting since you say the fault occurs dependent on the brake pedal moving forward or back slowly and not quickly. If the sensor is worn out, it may have an intermittent output at certain rotational positions which may have a better chance of being detected by the computer when the pedal is moved slowly. Just a guess. The skid control ECU normally monitors this sensor though and should throw a DTC code if it is malfunctioning.

 

I have an additional input or symptom on this problem that makes absolutely no sense. I was checking the fuse panel behind the small dashboard compartment on the left side of the steering wheel. In checking the fuses I accidentally broke fuse #45 (10 amp, Air conditioning system, rear heater system, rear window defogger, hybrid system). Obviously, the climate control immediately stopped working.
At this time the VSC alarm was on continuously and had been for 3-4 days. I drove the car this way for approximately 30 minutes (alarm blaring) while I made several stops for errands (turning the engine off and on at each stop). On my last stop before going to the auto parts store for a new fuse, I started the car and there was no alarm. This actually caught me by surprise because the alarm had been continuous for those 3-4 days.
I got to the auto parts store and bought the replacement 10 amp fuse for the air conditioning and replaced it. When I started the car the VSC alarms stayed off. It remained off for two days until it started again.
I decided to find out what would happen if I intentionally removed fuse #45. After removing the fuse, the alarm again continued for approximately 30 minutes through trips to the store, etc. However, after 30 minutes the alarm went off and has not returned for the last five days. During this time the brakes are working normally and exactly as they should.
This whole thing reinforces my opinion that Toyota telling me that the ECU has to be replaced (which I still haven't done due to finances) is a bunch of hooey. It also reinforces two of the opinions I've received from this panel concerning the ABS pumpmotor or the brake pedal stroke sensor. I believe that pulling the fuse on the air conditioning has lowered the voltage load on the 12 volt system (battery is brand new) and thus increased the voltage to some other system (pumpmotor, stroke sensor, ???).

Has anybody got any other suggestions before I start randomly replacing other parts?

Thanks, Bill

 

I have a 2006 Highlander Hybrid AWD-I with 110K miles. I just experienced the anti-skid light, Check VSC warning, Check AWD warning and ABS lights simultaneously come on when starting, however the vehicle drives normally. The start battery is about 6 months old however I suspect it may be the source of the problem because when I started the vehicle I had the heater fan set to High. When I turned the fan switch off and restarted the vehicle, no lights appeared. Two days ago same thing happened when I started vehicle while lowering a power window. Again, restart resolved the issue. My guess is that in both cases the additional drain on a less-than-perfect start battery may have caused the glitch.
Any comments would be appreciated, and I will update my post once a permanent cause/resolution is found.