Circuit Diagram of Brake Master Cylinder Diactivation Switch SW-6351 - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 10-09-2012
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Circuit Diagram of Brake Master Cylinder Diactivation Switch SW-6351

Does anyone have the internal circuit for the Brake Master Cylinder Deactivation Switch (Part # SW-6351 or SW6351), located to the forward top point on the master cylinder? I have tried to test this switch and was getting some strange readings on a VOM. I believe the problems I am having are related to this switch but need confirmation as I think it is a supervised circuit with some sort of internal components. I tried to test it (the cruise control system) disconnected but it would not even activate at speed so there is either a resistor, a diode, or both. The service manual wiring diagram shows a basic switch NO when normal but when left disconnected the symptoms I experience don't show (supervised circuit would explain this). Thanks, in advance, if anyone has this switch and has taken one apart or knows of the reading when new/working so I can compare to the strange VOM readings I am getting. Service manuals are sometimes wrong, showing a variable pressure switch as an open/closed contact (simplistic, for simplicity sake). If it is a supervised circuit (as evidenced by it not even trying to activate when the switch is out of the circuit), that would explain the crude test results I got. So, no reason to purchase a new switch if the readings I am getting are nominal. If no one here knows for sure (the internals) then I may have to do what many stealerships (sic) do and throw parts at it until it works.

Last edited by Ranger69; 10-09-2012 at 09:04 PM. Reason: Clarified by correcting spelling
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Old 10-11-2012
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TTT or 'BUMP'
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Old 10-13-2012
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Additional Info, the CC self test passed with flying colors... I still think it is the deactivation switch but want to verify no other components are internal to the switch before I 'test' jumper the switch out of the circuit for a few days. No one knows of the switch internals?
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Old 10-13-2012
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It is just a simple on/off switch, nothing fancy.

You didn't give the year of your Ranger. The Deactivation Switches for several years are covered under a recall for internal leakage and current flow through the brake fluid to ground. Some fires have resulted. Your dealer can look up by VIN to see if yours is affected or you can check the VIN yourself at Recall Notices| Ford, Lincoln & Mercury Owners | Official Ford Owner Site
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Old 10-13-2012
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Quote:
Originally Posted by rwenzing View Post
It is just a simple on/off switch, nothing fancy.

You didn't give the year of your Ranger. The Deactivation Switches for several years are covered under a recall for internal leakage and current flow through the brake fluid to ground. Some fires have resulted. Your dealer can look up by VIN to see if yours is affected or you can check the VIN yourself at Recall Notices| Ford, Lincoln & Mercury Owners | Official Ford Owner Site
Hi rwenzing, mine is an 01 and it has already had the recall fix. Am having a problem with it engaging and think I have it down to the deactivation switch. I was testing it with a VOM but it was giving me some strange readings. It's intermittant and the reading were consistant with a form of supervised circuit so I didn't want to jumper it out for a couple of test drives. You wouldn't happen to know the size of the fuse they put inline with the wiring (basically the entire recall fix, a harness with a fuse inline) would you? Somewhere I heard the fuze was a 20 amp but that sounds extremely high and as a second note, I don't want to cut the seals off my recalled harness in case something happens (they sealed it for a reason right?)... Anyway, I think I'll just go ahead and jump it out and see if the system works correctly all the time. I know I will have to cut it off and on by the control pod on the steering wheel. Thanks for replying!


Wait a min... Re-reading the 01 ranger factory wiring manual (310-03-00-4), the switch indicated an open condition when the cruise control is working. Note 2 says when the brake is applied it then sends system voltage ( switches 12v bus) to pin 9 of the speed control servo and pin 13 on the ABS control module. If this is true, when I disconnected the wire off the switch to test if it would work, it should have allowed the cruise control to work. It did not. Re-connecting the switch harness (with or without the recall fix harness in the circuit) got me back to the intermittant operation of the CC. BTW, the CC testing proceedure completes successfully on all occasions. Nothing seems wrong with any of the parameters the testing proceedure diagnoses. No error codes are indicated. Dang it! I'm right back to square one....

Last edited by Ranger69; 10-13-2012 at 02:54 PM.
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Old 10-13-2012
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Quote:
Originally Posted by Ranger69 View Post
Wait a min... Re-reading the 01 ranger factory wiring manual (310-03-00-4), the switch indicated an open condition when the cruise control is working. Note 2 says when the brake is applied it then sends system voltage ( switches 12v bus) to pin 9 of the speed control servo and pin 13 on the ABS control module. If this is true, when I disconnected the wire off the switch to test if it would work, it should have allowed the cruise control to work. It did not. Re-connecting the switch harness (with or without the recall fix harness in the circuit) got me back to the intermittant operation of the CC.
The Deactivation Switch is NC. The 2001 and 2002 Ranger Wiring Diagrams manuals incorrectly show it as NO.
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Old 10-14-2012
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Originally Posted by rwenzing View Post
The Deactivation Switch is NC. The 2001 and 2002 Ranger Wiring Diagrams manuals incorrectly show it as NO.

Damn factory manuals, checked my 02 manual as well (bought the 02 one first, then found the 01 manual real cheap so only looked up the 01 manual), now I know why it was so cheap! In addition to the note explaining the deactivator switch correctly, the wiring on the brake switch shows when you change the state of the switch it dumps system voltage to ground. Where the hell are the proofreaders (please don't say factory techs that screw up customers cars and wind up replacing a whole lotta crap on the customers dime). This explains some of the screwy readings/conditions present in my girl. I guess its time to order a deactivator switch (contacts must be worn out/dirty, was getting variable resistance values instead of virtual short).
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Old 10-18-2012
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??? OK which deactivator switch is it (or is a fit and OK for cross reference)? I found originally the SW6351 but now another source said the SW6350 is the correct one. If the master cylinder is the same, whats the difference? Also, is the connector the same for either if the threads are the same?? So, mine is an 01 Edge 2x4 with the 4.0L SOHC.
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Old 10-18-2012
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Quote:
Originally Posted by Ranger69 View Post
??? OK which deactivator switch is it (or is a fit and OK for cross reference)? I found originally the SW6351 but now another source said the SW6350 is the correct one. If the master cylinder is the same, whats the difference? Also, is the connector the same for either if the threads are the same?? So, mine is an 01 Edge 2x4 with the 4.0L SOHC.
Motorcraft # SW-6351 or Ford # XW7Z-9F924-BA
is for 1995~2003 Windstars ONLY

Motorcraft # SW-6350 or Ford # 1L1Z-9F924-AA
is the correct repair kit for 1995~1997 and 2001~2003.5 Rangers
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Old 10-19-2012
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Originally Posted by rwenzing View Post
Motorcraft # SW-6351 or Ford # XW7Z-9F924-BA
is for 1995~2003 Windstars ONLY

Motorcraft # SW-6350 or Ford # 1L1Z-9F924-AA
is the correct repair kit for 1995~1997 and 2001~2003.5 Rangers

rwenzing, this is two times in a week you have saved me headaches/$... If this keeps up I'll have to put this forum on my speed dial (a joke cuz I use dialup at home)... Thanks Bud!
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Old 10-23-2012
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Got my switch delivered BUT when I went to install it, found out the DOT3 I THOUGHT I had, I hadn't..... So, just another day or two (to acquire a bottle of DOT3 so I can place a couple drops of that whole can into the sw B4 I screw it onto the master cylinder), till my CC is 100 (or so) %....
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Old 10-29-2012
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Belated followup! Installed the generic 'Rock Auto' CC deactivator switch. Followed a recommendation posted somewhere, that made sense. Placed a few drops of new DOT3 fluid into switch fitting, then removed the defective one. Holding the new (fluid filled) switch fitting up, I placed it next to the master cylinder where the old one was and quickly flipped it over. Screwing it in, hardly any fluid escaped and the air (as much as humanly possible) was prevented from entering the system. As instructed, had brake pedal depressed steadily as some fluid oozed from the fitting. Not seeing any bubbles, I loosened a few and then tightened it tight. Cleaned the slightest amount of brake fluid from the master cylinder manifold and checked the pedal feel. Confident the brakes were OK, I took it for a test drive up the cul-de-sac at the end of my street. Cruise worked fine throughout and paired with the new (pre-owned) CC pods on the steering wheel, everything was great! Came home and did a couple of the CC self tests and when they all checked out, cleaned the tools. Next morning after a trip downtown the night before, I checked the area around and below the new CC switch. Nothing found leaking and fluid was exactly where I left it. All done, and CC is A-OK again!
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Old 10-30-2012
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