smshelton

Help! I have a 2006 lexus gs430 . On a few different occasions I have went to reverse and the car seems to accelerate back and I press down the brake as hard as I can and it wont stop it. After a few seconds it eventually brakes. I have had a mechanic go top to bottom on the car and he hasn't found a problem. Actually after the last time he said he couldn't find anything I was going to leave and it did it again as I was leaving! like I said it is randomly so it is making ir difficult to diagnos the issue. has anyone else had any problems like this?? Please Help!

MX73

Maybe you're pressing both the gas and the brake pedals at the same time. Maybe the throttle might be stuck open a bit?

Does the brakes work when as you shift the car into reverse (holds the car in place while you're shifting out of park)? I mean, you had to press the brake before you shift into reverse and let go of the brakes to let the car roll. If that doesn't happen, maybe there's an issue with the transmission.

smshelton

Thank you so much for responding..... I know it isn't me pressing the two pedals at the same time, Yes like you said my foot will be pressing the brake down to back up and even with the pedal pressed the car accelerates back. the mechanic said he has checked everything including electrical stuff and cant find an issue.....

Gs3500

It's a real safety issue,,, probably consider taking it to the dealer even though they will charge you an arm

smshelton

Yes you are right about the arm and the leg. I was just trying to see if anyone experienced anything closely relately to kind of give them something to go on. My mechanic is pretty experienced with Lexus but still has tried everything and can't figure it out :/ I have a feeling if I take it then they will charge me an arm leg and my first born Then tell me they still can't diagnose my issue lol

iGS430

You might want to do a VSC system calibration if you've recently done any kind of brake service on your car.

Sodium

Hi Shelton, interesting problem you've got on your hands.

A few questions:

1. Do you ever have any issues with insufficient braking force when you're driving forward?
2. When this happens, does the brake pedal feel any different than usual (eg. spongy, overly firm, pulsating, etc.)?
3. Do you hear a hissing sound, like a leak of pressurized gas?

From your description, it sounds like you're not getting any power assistance from your brake booster. Am I correct to assume that the engine was at idle power when this happened (i.e. you didn't have trouble braking because it spontaneously throttled up to 4500 RPM when you shifted to reverse)?

Gs3500

Perhaps a zero point calibration can also be done to reset all those sensors.

smshelton

alright thank you!

smshelton

HI Thank you for responding, To answer your questions, none of those things happened. But yes the engine was idle when I shifted into reverse, I did not catch was the rpm's were when I shifted to reverse. It was just like as soon as I put it in reverse it accelerated back without my foot being on the gas and still pressing down on the brake pedal.

NotADood

This was the first thing that popped into my head. I did this accidentally when driving a family member's Honda Odyssey. It scared the Bejeezus out of me. I had no idea what was going on until I did it the third time, and I realized that the brake and gas pedals are much closer than the vehicle I was used to driving.

smshelton

Lol unfortunately I wish that were the case, the same thing has happened to my boyfriend when he drove the car.

ibidu1

iTrader: (1)

Sounds like you may have a dirty throttle body not able to fully close quickly enough. If theres carbon or grime in the throttle body plate it would have less response feedback. I would remove the throttle body and clean it on the inside and out

ibidu1

iTrader: (1)

It wouldnt hurt to do a top engine clean either say with a product like seafoam ran through a vacuum on the intake and replace the plugs with oem plugs

smshelton

Thank you! All of these tips are so helpful,they at least give me somewhere to start! I will def have to update y'all as I get the recommendations done..... Just curious but has anyone else experienced this problem?