No fluid getting to rear brakes

[austinnelson117]

I saw that but wasn't sure what it was. How do I know if it has been "shut off"? And how do I go about trying to turn it back on? And since both the front and rear brakes go through this wouldn't it affect both systems? One more thing, when I do hit the brakes, the parking brake light comes on, I read that this happens when there is a difference in pressure between the two braking systems.

[PastorMike]

I think that we are talking about the Hydraulic Pressure Differental Sensor that resides under the Master Cyl. There is a shuttle piston inside that moves off center when there is unequal pressure between the front and the rear. If I remember correctly, there are wires connected to a sensor within the unit that senses this imbalance and triggers the brake warning lamp.

[austinnelson117]

So would I be safe in assuming the difference in pressure would be due to the rear brakes not getting any fluid? With the master being the problem? I'll probably start there since I can get a remanufactured one at NAPA for $50 after the core charge of bringing mine in.

[LeonV]

So would I be safe in assuming the difference in pressure would be due to the rear brakes not getting any fluid? With the master being the problem? I'll probably start there since I can get a remanufactured one at NAPA for $50 after the core charge of bringing mine in.

Isn't this what I said in my first post? Did you search any of the terms I gave you? Hmmm...

[austinnelson117]

You said, "This sounds like the emergency switch has shut off the rear circuit, a new master may not solve anything." Yes I did search what you told me to, as I have before. From what I read the Differential Pressure Switch simply alerts you of a problem not causes one itself. I found nothing about it "Shutting off the rear circuit". I concluded from my research that the master is bad causing the differential pressure switch to recognize an imbalance, therefore making the parking brake light come on.

[Alex K]

Oh trust me, we searched for a long time. We also drove the car with 50% braking power. Thing's fun to drive. We also used a twig to hold the shifter in place. How's that for safety, Leon?

Edited November 29, 2011 by Alex K

[austinnelson117]

LMAO, oh Alex

[Alex K]

we'll figure this out ourselves.

[beermanpete]

The emergency switch (pressure differential switch) is suppose to reset itself upon correcting the problem that caused the imbalance in the pressure. It has been mentioned in other posts on this subject that it is capable of blocking, or at least restricting, the flow of brake fluid. I doubt that it would because that would interfere with bleeding the brakes.

[JeffMopar]

Austin, You may want to just start with the basics and start loosening line fittings at the Master cylinder to see if you get fluid. If you do go tighten the fitting and follow the line down to the next one and try again. Keep following till you get to the wheel cylinders. Also, the rear ports on the Master (closest to the firewall) go to the front brakes not the rear as previously stated. Thats why the rear reservoir is bigger to hold more reserve fluid for Disc brake systems so that as the pads wear down the fluid transfers to the caliper to maintain proper pad clearance.

Hope this helps, Jeff

[LeonV]

You said, "This sounds like the emergency switch has shut off the rear circuit, a new master may not solve anything." Yes I did search what you told me to, as I have before. From what I read the Differential Pressure Switch simply alerts you of a problem not causes one itself. I found nothing about it "Shutting off the rear circuit". I concluded from my research that the master is bad causing the differential pressure switch to recognize an imbalance, therefore making the parking brake light come on.

I misread your post and apologize. I though you were going to buy a new switch. There is no need for your buddy to be immature about it.

[austinnelson117]

Well when we took off the master we made our best attempt at cleaning it but im sure there is still gunk in it, the bolts on the bottom are pretty rusty and I suspect they arent getting a good seal and I dont want to fool aroung with brakes so I'm going to pick up the master today after school and see what that does for me. Leon, don't worry about it, just a misunderstanding.