RABS dump valve leaking, supposedly

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Mar 3, 2014 | 07:50 AM

ham-n-swiss

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From: Fullerton, Ca.

RABS dump valve leaking, supposedly

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ontVertAlignInTxbx/> <w:Word11KerningPairs/> <w:CachedColBalance/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]--> Question: I just had some work done to the rear brakes of my 90 F-250 (RWD). I have had a spongy pedal for a very long time. The guys at the shop told me my RABS dump valve is leaking internally. I did a little research on how the system works and it seems that an internally leaking dump valve could very well cause the condition I’m experiencing. One thing to mention though is when the engine and ignition is off the pedal is rock solid. This got me thinking, if the valve is leaking wouldn’t it leak all the time and the pedal should be spongy even with the ignition off? Could the valve be just fine and the RABS controller or a sensor be the culprit? I’m not getting a ABS light indication on the instrument cluster. And yes, the light does work. Can I just unplug the four wire connector to the RABS valve and confirm my suspicion that the valve unit itself is fine if the pedal remains hard with the engine on but the plug disconnected?

Any and all help most appreciated!
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