Comments Please, (05 SRT): Brakes spongy and were to be checked at scheduled service, the day before, while driving in town it seem to power down not die, just power down five times. After lunch I took it the chrysler garage, they read codes and said fluid was bypassing in the master cylinder and all related to "powering down", BAS light was on. Master cylinder ordered, repairs to continue Mon June 6. Does it sound like correct diagnosis?

 

Powering down that is a new one on me relative to brakes.
What is your description of it?

 

You try gravity bleeding your brakes?

 

If you are talking about the car actually cutting power when you apply the brakes then it make since. Our cars have a brake master cylinder pressure sensor, I'm guessing there is a set pressure at which the brakes should reach when they are applied. On your car if the master cylinder cups are bad it will make it so the pressure can not be built up enough which then the car figures it will cut power to help you slow down.

 

Powering down, without changing throttle position and not braking, rpm's drop to about idle then back to original in seconds. The tech said the bypass was causing brakes to be applied, and the master cylinder was at fault. If its sounds right we'll fix it, I just don't want to start replacing parts to isolate the problem,
Thx

 

Frankly that explanation does not sound plausible to me. Why would the brakes be applied for no reason? I can hear the brakes when they are rubbing against the rotors, can you hear them when the revs drop?

 

No I don't agree with that theory, because I wasn't braking therefore not using the master cylinder, but the tech said the code indicated the M/C was bypassing, causing the secondary problem. I think it might be best to have the brakes bled first then go from there.

 

Is this an automatic or a manual?
What theory do you not believe?

 

It is automatic, and I don't believe that the loss of power problem has anything to do with the brakes. I put 220 miles on the car last monday (with spongy brakes) with no problems, service was already scheduled. I just think there two seperate problems, if there suggestions please advise. Thx

 

I think that the throttle position sensor, the accelerator pedal sensor or a bad connection in that circuit are at fault.
Unplug and reconnect all the connectors in that system a few times and hopefully it is a bad connection.

 

Thanks onehundred80, I'll get them to service, bleed brakes and check those sensors before continuing with anything else--will update tomorrow nite hopefully, Thx

 

Just wondering if when the fluid is getting out of the master if it's leaking into the power booster. Since that's run by engine vacuum I'm thinking he said that because maybe the booster unit is getting full of fluid and somehow causing that not to work correctly. That might make the car feel like it's low on power. But, have you checked your brake reservoir to make sure that there's a fluid loss to begin with?