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08 Knight brake light switch location...


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I have searched through the files to no avail...No brake lights, fuse good in rear compartment. I see on the firewall the air brake actuator (?) with two attached components with 3 wires coming from both.

Looked as best I could at the brake pedal and did not see a switch there.

Any help would be greatly appreciated!! TIA

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There is an active thread about this currently, I asked the question Oct 5... my inop brake lights seem to be a problem with the switches mounted up front above the generator.... 

Look for "Brake Lights not working"

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I have contacted Nason about the switch for brake lights…they say they stock virtually nothing. BUT sent me the name of a company in Ohio that orders this switch regularly. I was too late to call on Friday and sent an email instead. Looking forward to getting the brake lights working! Will post if I make progress with the supplier.

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5 hours ago, Capt Mike said:

name of a company in Ohio that orders this switch regularly. I was too late to call on Friday and sent an email instead. Looking forward to getting the brake lights working! Will post if I make progress with the supplier.

I'm still looking for a source for new switches (2), please let me know what you learn, Thanks, Ken

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41 minutes ago, Capt Mike said:

AND…Veruniks in Michigan says they have them in stock!  For only $198 each plus shipping!

That is some serious price gouging there!

8CCFEB7D-4166-447D-8B2E-8A92E4ACC467.thumb.jpeg.dc329e38aeac0d64cc1dc94f164c13df.jpeg

 From the Parts list Nason Distributors or Vendors.....

ORDER from Distributors Below DIRECT
Cross Company 866-219-8217 - GRUMPY FOLKS!
Sunsource 800-228-5800
Flow Dynamics 205-581-1200
Hydraulic Energy Products 800-800-3471
Fluid Power Equipment Co., 877-471-8999
Hydraulic Controls in Phoenix 602-278-6088 or 510-658-8300
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Questions for you, Capt Mike…or OTHERS…

since you visited the OTHER thread, and it is also, based on the pictures, a 3 wire switch, have you tested or trouble shot or found the Monaco wiring diagram for the switch.  The one that I found with the same three wires is a Low/High switch.  Presumably factory set and adjustable around 70 PSI.  So, there are two outputs.  Can you help us understand where the two circuits go or are used?   

From the OTHER post, I pulled this out.  The OEM Monaco switches, which were 2 wire are simple ON/OFF SPST switches…and are actually a 3 PSI operated switch.

https://www.haldex.com/en/na/electrical/electro-pneumatic-switches/be13250/  So, the slightest pressure would operate them.  Now, I don’t know from the poster who provided that, what the OEM PN was and we cannot check the specs.  But, he reports that everything is working OK.

Just curious…..as I think it would help folks with the trouble shooting.  In your case, there may also be a different vendor that makes the same switch….but without the circuit information, chasing that might be futile.

In addition, @Frank McElroy can add your switch info as well as the 2 wire switch info to the parts list.  There is no “Brake Light” switch called out in the Parts list…so others would benefit.  I know Monaco did strange things.  But, I can’t understand the two different pressures.  If I understand the treadle operation, there is compressed air released or ported to the brakes when the pedal or actuating rod is pushed and that opens the valves in the treadle,  what I can’t understand is why there are two switches….nor  can I understand why there are TWO simple ON/OFF (3.0+PSI) switches are needed.  Muchless, two SPDT switches….

ONE THEORY….and just a theory…..one switch brings ON the Brake Lights and the other “kills” the cruise control….or disables the circuit.

Any insight, from anyone, would be appreciated.

Thanks.

 

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I'll add to the parts list on the next update.  I've looked at a few wiring diagrams and in some cases Monaco would use the NC wire on one of the switches to cancel the cruise control when the service brakes were pressed.  I'll include that precautionary statement because replacing a 3 wire switch with a two wire switch might not be applicable on all model coaches.

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Frank, I got a couple part numbers for 00 Sig, likely some others of that era as well. All 2 wire.

Brake switch (two)   Meritor 8940416052

Cruise cancel switch (two)  Nason SM-2B-5F /QC

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Frank and I spent a lot of time on the phone....and he just posted about the parts list.  He pulled a lot of prints.  after going over the circuits, there are some things that can be safely or logically said.  In the 2008 Knight issue....this post.  Here is a diagram of the wiring...or a blow up.

Capt Mike....as well as others.

From your previous posts you said that you "Swapped Around" the switches and ALL IS WORKING.  This is our best explanation from the circuit as well as your comments.

First, you may NOT actually have a BAD switch.  The Switches are actually, if you look, in parallel.  The reason, the treadle valve is actually TWO DIFFERENT braking circuits. So, if one system (the rear is the PRIMARY) fails, then you have the Front, to rely on.  It is MY understanding that the Treadle valve actually modulates the air...so that the Primary braking comes from the rear drums....then if the pedal is pushed harder....the front (Disc) kicks in.  Either way.....there are TWO BRAKE LIGHT SWITCHES....and either one (in parallel) will activate the Brake Lights. 

NOW....that brings up an interesting question or dilemma....WHY DID BOTH FAIL?.  Probably they did NOT.  That environment under and above the Genny is hostile.  The PN that you posted has a WeatherPack (WP) designation.....as in in HOSTILE.  BUT, what MAY have happened is that the connectors have corroded over the years.  The THEORY.....and take it as that.....  You actually LOST the Brake light signal on one switch.  Last week or last month or last year or last 8 years.  WHO KNOWS.  BUT, the OTHER switch worked.  If you "SWAPPED" them around..... MAYBE you unplugged BOTH CONNECTORS.  THEN you removed the switches and swapped them.  THEN you plugged in the connectors again.  IF THERE WAS CORROSION....then it would not (could ?) be in the same location.  SO, you actually made a GOOD connection.  Maybe there was a little corrosion or an issue in the contacts on the switch(s).  By removing them, you also bumped or dislodged something.  OBVIOUSLY....the possibilities are endless.

NOW....it is WORKING.  BUT, using the corrosion theory, here is a suggestion.  It has worked for OTHERS....me included.  There is a product called NoAlox or a Gardiner Bender equivalent.  Home Depot carries it (Google the name).  You want the PASTE.  Take a toothpick or a small screwdriver or maybe end a small Q-Tip. I had a really crappy connection on my Toad's 6 pin connection and had no BRAKES.  I just started a 6 week trip.  I stopped at Lowes (Gardner Bender....Lowes USED to stock the NoAlox).  I bought it and then went into the sporting goods section and bought a .177 or 17 Caliber brass brush.  I cleaned the female terminals with the brass brush and I used a small screwdriver and scraped the male ones.  I then put a tiny portion of the NoAlox inside the female and on the male.  Then I plugged and unplugged the umbilical for maybe 5 times to burnish.  This is an electrical paste.  Designed for Aluminum....and an anti-oxidant.  BUT, it works on copper and plated terminals.  Do THAT on the two mating plugs.  BUT, the last time, get some Bulb (Dielectric) grease and put a smidge on the terminals, right before they fully seat.  That seals them.

That will improve the connection.  THEN DRIVE ON.  If you have problems, then find the switches. BUT, unless you do some trouble shooting and such, you will have to follow the wiring diagram.  NOTE.  One disconnects the CRUISE.  The OTHER DOES NOT.  SO....be aware that YES, the switches are the SAME....but they are NOT wired the same.  One has a contact NOT USED.  Figure out which one or replace both.  ALSO, follow the wiring.  You COULD also have a bad Brake Light Relay.  There are TWO relays, typically that are in parallel.  One is controlled by the Brake Pedal Mechanical Switch (inside) and the other is controlled by either of the Nason switches.....they go bad also....

Good LUCK.....this now explains, based on Frank's knowledge and my asking questions WHAT PROBABLY HAPPENED....

2008 Knight Brake Light Switch - Comparable Wiring.jpg

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Please accept my apology as I have been out of pocket (new granddaughter) and unable to read, much less respond to all the posts regarding the Brake light situation. After perusing the previous posts it appears as though the situation has been "handled"? I see the PN for the Nason switch has been published as well as the suppliers. If I can be of any assistance further, please let me know.

And a huge shoutout to the moderators of this page who have assisted with the education of my Monaco!

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