Master7122 Posted January 26, 2017 Share Posted January 26, 2017 I'm leaking brake fluid out of the top of a gold piece where all my brake lines connect. I think its called a proportion valve? Anyways its like a sensor for the light in the cab to come on when its low. My light doesn't come and so I would assume that its no good. Its kinda yellowish in color and is directly on top with a connection going to it Link to comment Share on other sites More sharing options...
big66440 Posted January 26, 2017 Share Posted January 26, 2017 I believe it's called a distribution block on our trucks, if that's what you are talking about it's not available from the aftermarket. You're best bet would be to post a wanted ad in the classifieds or ebay, or you can pull one off of an XJ but you may have to modify it. Link to comment Share on other sites More sharing options...
Master7122 Posted January 26, 2017 Author Share Posted January 26, 2017 I believe it's called a distribution block on our trucks, if that's what you are talking about it's not available from the aftermarket. You're best bet would be to post a wanted ad in the classifieds or ebay, or you can pull one off of an XJ but you may have to modify it. I just need the sensor that goes into the top of it Link to comment Share on other sites More sharing options...
Eagle Posted January 26, 2017 Share Posted January 26, 2017 It's not a sensor, it's a plunger switch. You can use one out of any Cherokee or Grand Cherokee. The switch is the same for all of them, although the valve/block bodies are different. Link to comment Share on other sites More sharing options...
Master7122 Posted January 26, 2017 Author Share Posted January 26, 2017 It's not a sensor, it's a plunger switch. You can use one out of any Cherokee or Grand Cherokee. The switch is the same for all of them, although the valve/block bodies are different. Thanks eagle! Do you know if I can get one from a auto zone or advanced? Also if the plunger failed would that cause the brake light to not come on the dash when the fluid is low Link to comment Share on other sites More sharing options...
schardein Posted January 26, 2017 Share Posted January 26, 2017 The switch on the combination valve (or proportioning valve, or distribution block) is a pressure differential switch. It does not tell you the brake fluid in the master cylinder is "low". It does tell you if a leak has developed somewhere downstream of the valve and you are now operating on either the front or rear brakes ONLY, depending on where the leak/failure is in the system. Also, it may be activated if the master cylinder is EMPTY and only one circuit (front or rear) has enough fluid remaining to operate. Link to comment Share on other sites More sharing options...
schardein Posted January 26, 2017 Share Posted January 26, 2017 Also, not sure how you are determining the pressure differential switch is bad. The brake light on the dash could be out. It is the same light that should come on when the parking brake is applied, so that is one way to test it. Although if it does not come on when the parking brake is applied that doesn't automatically mean the bulb is bad, it could be a bad switch on the parking brake or a fault somewhere else in the circuit. Link to comment Share on other sites More sharing options...
Master7122 Posted January 27, 2017 Author Share Posted January 27, 2017 The light comes on when I turn the key to the on position so I know it works. And I didn't know if that is what told me I was low because 1. Its leaking badly and 2. When I went dry in the master cylinder from that leak, the brake light didn't come on Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 27, 2017 Share Posted January 27, 2017 HERE you go. A mere $149.95 on Ebay. They don't sell the switch separately.  :nuts:  Link to comment Share on other sites More sharing options...
Master7122 Posted January 27, 2017 Author Share Posted January 27, 2017 I see a junkyard trip in the near future Link to comment Share on other sites More sharing options...
schardein Posted January 27, 2017 Share Posted January 27, 2017 Is that what your switch looks like? Â Cause I might have one laying around. Link to comment Share on other sites More sharing options...
Eagle Posted January 27, 2017 Share Posted January 27, 2017 Here's the cutaway view: Â Â Â As you can see below, it's the same switch in an XJ proportioning valve: Â Link to comment Share on other sites More sharing options...
Master7122 Posted January 27, 2017 Author Share Posted January 27, 2017 Is that what your switch looks like? Cause I might have one laying around. Yes mine looks just like that one except its all gold and not silver Link to comment Share on other sites More sharing options...
Eagle Posted January 27, 2017 Share Posted January 27, 2017  Is that what your switch looks like? Cause I might have one laying around. Yes mine looks just like that one except its all gold and not silver   No, you're referring to the entire distribution block (or proportioning valve, in the case of the XJ). The switch is just the small, plastic thing that screws into the top. If that's what's leaking on yours, that's all you need, and the XJ part is the same as the MJ part. (And I'm 98.37% certain it's also the same on the ZJ Grand Cherokee.)  However:  Take a look at the two cutaway photos I posted. It occurs to me that you may, in fact, need the entire valve assembly. The plunger switch itself should be isolated from brake fluid by the O-rings on the shuttle valve (that horizontal thingie that slides back and forth in the top of the valve body). If you've got brake fluid coming out the switch body, that's an indication that at least one of the internal O-rings has failed. I don't think the switch is intended to have contact with brake fluid. Link to comment Share on other sites More sharing options...
schardein Posted January 27, 2017 Share Posted January 27, 2017   Is that what your switch looks like? Cause I might have one laying around. Yes mine looks just like that one except its all gold and not silver   No, you're referring to the entire distribution block (or proportioning valve, in the case of the XJ). The switch is just the small, plastic thing that screws into the top. If that's what's leaking on yours, that's all you need, and the XJ part is the same as the MJ part. (And I'm 98.37% certain it's also the same on the ZJ Grand Cherokee.)  However:  Take a look at the two cutaway photos I posted. It occurs to me that you may, in fact, need the entire valve assembly. The plunger switch itself should be isolated from brake fluid by the O-rings on the shuttle valve (that horizontal thingie that slides back and forth in the top of the valve body). If you've got brake fluid coming out the switch body, that's an indication that at least one of the internal O-rings has failed. I don't think the switch is intended to have contact with brake fluid.  Entirely correct. Link to comment Share on other sites More sharing options...
Master7122 Posted January 28, 2017 Author Share Posted January 28, 2017 Brake fluid is coming from where the plunger screws into the block, do I need entire block or just that plunger then? Or an o ring? Link to comment Share on other sites More sharing options...
Eagle Posted January 28, 2017 Share Posted January 28, 2017 Brake fluid is coming from where the plunger screws into the block, do I need entire block or just that plunger then? Or an o ring? Â The plunger doesn't screw into the valve body, the switch body screws into the valve body. The plunger is in the switch. What I was trying to say is that brake fluid should not get to the plunger or the switch body. You need at least an O-ring, but who knows which one, what size it is, or what type of rubber it's made of? It's probably easier in the long run to replace the entire assembly -- the distribution block. (Or "valve/brake" in Hornbrod's photo) Link to comment Share on other sites More sharing options...
Master7122 Posted January 28, 2017 Author Share Posted January 28, 2017 Alright, I'll just find the part at the junkyard, thanks everyone for the help Link to comment Share on other sites More sharing options...
Eagle Posted January 28, 2017 Share Posted January 28, 2017 Keep in mind that, although the actual plastic switch is the same for the XJ, MJ, and ZJ, the overall distribution block/proportioning valve (the body) is not -- as can be seen in the two cut-away photos I posted above. The MJ has the proportioning function handled by the height-sensing proportioning valve mounted to the frame above the rear axle, and there are two lines from the distribution block to the rear. For the XJ and ZJ, the front valve block handles proportioning and there is only one brake line from the proportioning valve to the rear axle. Â That means you will have to find one from an MJ to accomplish a drop-in, OEM replacement. You can use a proportioning valve from an XJ or ZJ, but you'll have to abandon the second line and the height-sensing proportioning valve. And, since ZJs has disc brakes in the rear, I believe (but I'm not certain) that the proportioning valve for the ZJ was calibrated differently than that for the XJ. If you're going to go that route, I don't know which would work better in an MJ. Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 28, 2017 Share Posted January 28, 2017 I doubt you will find the MJ distribution block easily at the yard. If you can't find one, I'd unscrew the brass valve stem and bring it to your local Mom and Pop auto parts store that's been there about 100 years (most every town has one), rummage through their o-ring assortment box and replace every o-ring on the stem. I'm betting you will probably find one or two of them torn or disintegrated. Also remove the plastic switch and make sure the body isn't cracked. Put it all back together and you'll probably be good to go. Link to comment Share on other sites More sharing options...
Master7122 Posted January 29, 2017 Author Share Posted January 29, 2017 I doubt you will find the MJ distribution block easily at the yard. If you can't find one, I'd unscrew the brass valve stem and bring it to your local Mom and Pop auto parts store that's been there about 100 years (most every town has one), rummage through their o-ring assortment box and replace every o-ring on the stem. I'm betting you will probably find one or two of them torn or disintegrated. Also remove the plastic switch and make sure the body isn't cracked. Put it all back together and you'll probably be good to go. I will try this thank you! I went to a junkyard and grabbed a xj one just in case the o ring method doesn't work. I know I may have to do some modifying but I think I'll be able to figure it out Link to comment Share on other sites More sharing options...
Eagle Posted January 29, 2017 Share Posted January 29, 2017 You could try just swapping the shuttle valve (the horizontal slider thingie) out of the XJ unit into your MJ unit, O-rings and all. That part is the same for both. (See the cutaway photos.) Link to comment Share on other sites More sharing options...
fiatslug87 Posted January 30, 2017 Share Posted January 30, 2017 Those are damn cool cut away shots! Thanks for posting them Eagle. Link to comment Share on other sites More sharing options...
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