Why does my car shake at stop with brake pressed down in drive but not when I am driving or in neutral?
2001 Lexus IS300 Automatic. I live in Utah and its cold right now. Just started a few days ago and sometimes the problem doesn’t happen. When I press the brake down completely i hear and feel a shaking or vibrating noise. The steering wheel shakes a little even. Sometimes worse than others. I put the car in neutral or park and the shaking stops. If I leave it in drive and put the E-Brake on there is no vibration. Only when I am pressing it down with my foot. When I accelerate it is fine. Also, one day the cruise control light would come on but I couldn’t get it to set. The next day it worked fine. There is sometimes a kind of shaking noise from 15-20 miles per hour while accelerating. The check engine light never came on. I took the car to a shop and they said there were all kinds of notifications from the computer of ABS failure or problems. They think the ABS sensors are fine but they think my alternator and battery are the problem. They put a new battery in and the problem still happened. They said my alternator is only putting out about 12-12.5 volts and it needs to be at 13-14 volts to power my secondary computer which is what powers the AntilLock Braking System. My car starts perfectly every day and always has. The radio works the headlights are full power. I never need a jump or anything. I can leave the car in idle with stereo and heater full blast and headlights on and nothing fades or dims or anything. The problem is only when pressing the brakes down at stop. They want 625 for a new alternator and battery but don’t guarantee it will fix the problem. What should I do and are they accurate with the 12-12.5 voltage causing these problems?
P.S. it is a 3.0 Liter engine and it does this even when I turn off the air, stereo, head lights, everything.
After reading more posts I thought I should add that the idle does not go up or down at all while stopped. It is at a consistent just above 1000 if I remember correctly.
Im not sure how to reply, but in response to Rosita, I had my alignment done a month ago so it should be ok. The car drives perfectly straight without holding the wheel. Also, it does not shake or vibrate while stopping at all. Only while stopped completely. Within the last second or two of coming to a stop the breaks do make a sound, a low kind of groaning type sound but no shaking. This led me to think it was the brakes but Les Schwabb said the brakes are great. They said I may have hit a hard spot on the brake pads and I am working through it. This was before the incident where the cruise control wouldn’t work properly, which it now does. Thanks for the quick response.
Thank you for the help with understanding the voltages. I think he said it was 12-12.5 running but I will check again tomorrow. He told me he thought the shaking would be caused by the ABS System because it is shorting from the lack of enough voltage to run the computer that the ABS is on they aslo suggested that the faulty ABS caused the cruise to not work because the tires weren’t measuring correctly. When I drove the car to the shop I didn’t really feel the vibrating or anything anymore. If the guage is below the 13.7 with a new battery and around 12.5 then what does that mean? Should I buy the new alternator?
To clarify, if while running, with a new battery in the voltage is only around 12.5 instead of the 13.7 you recommended then what does that mean?
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Tags: 2001 lexus is300, alternator, brakes, braking system, cruise control, dims, full blast, headlights, Lexus, Lexus IS300, liter engine, miles per hour, nothing fades, notifications, secondary computer, sensors, steering wheel, stereo head, vibration, volts
4 comments
ssg/emt on September 5, 2010 at 8:03 pm
You think like a mechanic!
If it was the ABS, it would happen in drive or neutral.
The fact that it only happens in gear means the transmission is most likely involved. It sounds like it is still trying to pull when you are stopping. You may have a problem with the torque converter. It locks up when you are moving fast enough that you no longer need the extra torque. That gives you higher mileage by reducing slip.
It sounds like it may not be unlocking quick enough. It’s like stopping in a standard transmission without pushing in the clutch.
I am not familiar with Lexus, but most automatics are computer controlled and a low voltage may screw with the solenoids and controls that shift the tranny.
You can buy a cheap multimeter at any parts store or Wal-Mart. Use that to check the voltage yourself after you clean the battery terminals.
It may be that they stumbled on a charging problem and that the shaking is unrelated. (which unfortunately means even more money)
Good luck.
Rosita on September 5, 2010 at 8:03 pm
My car did that when the tire alignment was off. You might need to get your tires aligned. It can get thrown off by hitting a pot hole or a curb, and it makes your car shake when you press the brakes.
helpful bob on September 5, 2010 at 8:03 pm
If I were you I’d buy myself a voltage meter and place it’s setting for 20 volt , place the negative on the negative batter post and the positive on the pos battery post and see what the current is.It should be over 12 volts, then try the same test with the car running and see if the current is above or around at least 13.7 volts.
The problem could be as simple as rusty or corroded battery , starter , alternator, engine block posts that need to be cleaned.
When is the last time the gas filter was replaced bec it should be replaced once a year.Make sure that all the belts are good and not loose especially the alternator belt.
The spark-plugs may need to be cleaned and re-gapped and wires may require their contacts to be cleaned or wires replaced and ignition coil may need to be cleaned.Also the different plug in contacts or sensors plug in connections could be getting moister in them or require cleaning , plus the ignition coil spark plug connections could be allowing moister in and need some anti moister jell to be applied or they could be corroded etc.
The cruise control issue could of been moister or a bad ground connection going to the cruise control system or the comp.
Hope that helps and best of luck.By the way I’d not worry too much about the minor shaking but I’d for sure check and double check the alternators output voltages and charging system connections , plus change the gas filter and keep in mind that in extreme temperatures and bec of moister etc some vehicles will act up slightly and it’s no big deal but again things could be cleaned and checked on it.
navi on September 5, 2010 at 8:03 pm
With the cold weather you have out there you definitely require an alternator that gives you at least 13.6 volts. Having said that I do not think that the fault is with your computer system failing as it is most likely designed to function should your battery drop to 10.5 volts. Most wheel alignment problems show up when breaking and wheel balancing shows up at about 50 mph. Have you looked at the engine and gear box mountings, much of what you write leads me to that. A decent auto electrical place will determine on test whether you only need new diodes in alternator rather than a replacement. ot cheaper. Is your alternator belt tight enough, if it is slipping you will drop voltage. Glad we don’t have your weather in the UK, good luck