1997 Dodge Caravan Left Front Brake Applies With No Pedal P

Tiny
SAJPHOTO
  • MEMBER
  • 1997 DODGE CARAVAN
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
I replaced the proportioning valve because it was leaking. The left caliper wouldn't release after I bled brakes. I replaced the caliper and it still wouldn't release. Replaced the flexible lines on both side. When I start the vehicle, the brakes are fine until I put the vehicle in Drive. After a few seconds, the left front brake engages when not touching the brakes. It seems that if I apply the gas and the wheel spins faster in happens more. I pulled the fuses for the ABS and that did nothing.
I pulled the speed sensor off the hub and got the rust off and that did nothing. With the speed sensor pulled off the hub and just hanging free the problem seems to become less frequent ( every 20 seconds ) as opposed to every 5-10 seconds but still present. I also replaced the proportioning valve a second time to eliminate that as the cause.
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Sunday, November 7th, 2010 AT 3:19 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Does the caliper release if you break the bleeder open?
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Monday, November 8th, 2010 AT 7:39 AM
Tiny
SAJPHOTO
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Yes it does release. It releases if the vehicle is taken out of drive and placed in park while running. It pulses on and off when the vehicle is placed in drive and the wheel is turning. Actually, pulse is incorrect. It engages for a few seconds and will partially release every 10 - 15 seconds. I replaced the caliper and hoses after the problem was initially found. If I remove the caliper and compress it with a c clamp, it opens up normally.
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Tuesday, November 9th, 2010 AT 7:08 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
My concern is there is a blockage. You said the rubber hoses to the caliper were replaced. That is where the problem usually occurs. However, the brake doesn't release if the vehicle is running. When using a C-clamp, you force the piston in, so I can't be sure it releases without the clamp. Honestly, I think there is a problem in the master cylender. The proportioning valve really has no serviceable parts that could be bad. It has to be the MC, caliper slides, rubber hose that attaches to the caliper, or a pinched steel line not allowing the caliper to retract pressure.
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Tuesday, November 9th, 2010 AT 10:39 AM
Tiny
SAJPHOTO
  • MEMBER
If the van is running and in park, the brakes will apply and release only when I step on the brake pedal (normal operation). If I then put the van in drive and allow the front wheels to spin, the left front caliper will engage and semi release when I am not applying the brakes. If it were a blockage, I don't believe it would have anything to do with the transmission being in drive and the wheels turning would it? What would cause only 1 caliper to receive a signal to apply? Is there an electrical "connection" between the brakes and transmission? ABS?
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Tuesday, November 9th, 2010 AT 11:10 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
There is nothing that can cause the caliper to do this other than a warped rotor (which makes contact and then doesn't) or if you are using the brakes. The system is hydraulic. It requires pressure to work. If there is no pressure being applied to the pedal, there is no way it can engage. (Nothing electrical to cause it).
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Tuesday, November 9th, 2010 AT 1:32 PM
Tiny
SAJPHOTO
  • MEMBER
The rotors are brand new also. The problem was there before and after changing them also so it's not the rotors. I also had taken the caliper off and and watched it as The vehicle was running and placed in drive etc. The piston would push out every 10 seconds or so. If it could only be hydraulic, I assume it could only be the master cylinder or the booster correct? If so which would change first? Thank you for your help.
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Wednesday, November 10th, 2010 AT 4:15 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Wow! 30 years in the business and I have to say I never saw this. It isn't the booster or the master cylender. It has to be related to the ABS. I reread the original post. A brake booster is run by vacuum. You mentioned when you gave it gas (vacuum drops) it would get worse. It should have done the opposite with less vacuum. As far as the master cylender or the brake booster, they wouldn't apply pressure to only one wheel. Is there any chance the brake lines were spliced and the other front wheel is getting (the one working correctly) is only getting pressure with the rear brakes?

At this point, I think the ABS is causing this. Have you tried disconnecting the sensor on that wheel? Also, if you have, make sure the wiring to it is good and not rubbbed through and shorting.

Let me know.
Joe
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Wednesday, November 10th, 2010 AT 3:12 PM
Tiny
SAJPHOTO
  • MEMBER
I did disconnect the the sensor. It was pretty rusty so I cleaned it up. With the sensor removed from the hub, the problem did not go away totally but did seem to be a little less frequent.
Maybe every 30 seconds as opposed to every 10-15 seconds.

I pulled the fuses for the ABS early on but it didn't seem to change anything. Is there a way to disable the ABS to see if that's the issue? I found 2 fuses marked ABS, are there more?

At least I don't feel too stupid. 30 years and you're scratching your head too.
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Wednesday, November 10th, 2010 AT 5:27 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
That is it, only 2. Good lord, I am going to ask another tech for his opinion. I will be in contact with you.

Joe
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Wednesday, November 10th, 2010 AT 11:08 PM

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