Brake question.

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Sep 16, 2012 | 08:20 AM

va150

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From: Virginia

Brake question.

I have a 87 F-350 that just started having brake issues. When I push the brake pedal down it feels perfect but if I let up just a little and push down again it gets soft. I have all new from and rear breaks, everything except brake lines which all look good. I am planning on replacing my master cylinder. First does this sound like the problem and second should I also replace the booster?

Sep 18, 2012 | 09:46 AM

Lazy K

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Can you explain what you mean by pedal "gets soft"? Does the pedal slowly sink or just feel spongy but not sink?
Your booster is not the problem.

Sep 18, 2012 | 01:05 PM

va150

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From: Virginia

After letting up on the pedal just a hair then pushing down again it is not spongy just sinks in an extra inch or so. If I let it up all the way and step on the break again it seems normal.

Sep 18, 2012 | 01:51 PM

Lazy K

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Very odd. Can only be fluid getting past master cyl seals or an intermittant fault in the RABS module (on inside of left side frame rail, about level with drivers feet).
Maybe remove the two nuts holding the master cyl to the booster, pull the master cyl forward and look for any signs of brake fluid. If any found replace the master cyl.
Maybe also bleed some fluid through the RABS module (bleed screw on it and bleeds just like a brake) and see if that helps.

Sep 18, 2012 | 08:34 PM

Muffinman

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From: Dallas, Texas

Check for any air in the system as well. You might look to make sure no fluid is leaking from any cylinders, I had a rear one go bad and it did the same thing.

I don't know if a 1987 even has a RAB, but I never seen one act like that. They will fault a code if pressure gets even the slightest uneven.

Sep 22, 2012 | 08:32 PM

va150

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From: Virginia

Finally replaced the master cylinder today, breaks work great now but the ABS light is on.

Sep 22, 2012 | 09:54 PM

Muffinman

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Joined: Jun 2004

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From: Dallas, Texas

Those things are a hand full to trouble shoot.

Try finding the black wire with orange stripe and red or pink wire on the other. The connector is under the driver side steering wheel dash, look to the right side of it and see if you find it.

You ground the black\orange stripe wire to a good ground, do this while the key is on. it will flash the code. Once you have that code you can narrow it down.

How to: Retrieve ABS trouble codes - Ford F150 Forum - Community of Ford Truck Fans

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Oct 4, 2012 | 02:57 PM

va150

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From: Virginia

What do I do if I can't get it to flash a code? The ABS list stays lit all of the time. I even replaced the RABS <!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w

oNotPromoteQF/> <w:LidThemeOther>EN-US</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w

ontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w

ontVertAlignCellWithSp/> <w

ontBreakConstrainedForcedTables/> <w

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]-->hydraulic <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority

9; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} </style> <![endif]-->cylinder and speed sensor. It never came on until after replacing the master cylinder.

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Oct 6, 2012 | 03:38 PM

Muffinman

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Joined: Jun 2004

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From: Dallas, Texas

You ground the test connector black and orange to any good ground for just s few seconds and it will flash the code out. count the flashes and then post it.