DennisZ

Unfortunately that was long ago, my memory and purchase history are long gone.

I had to replace my outside air temp sensor several years ago, mine is located in the fuel bay on the passenger side, the whole bay is open to the outside world, so an outside temp. On mine, it is not a thermocouple (2 dissimilar wires twisted), but a special diode, I had to buy like a hundred od them, but they were cheap.

Good thought, mine were definitely the switches, it would depend on how fast and hard I applied the brakes if they worked. Disconnected the switches, jumpered the connector and they worked every time.

Actually the 2 switches are both NO configuration and are wired in parallel, one for the primary air system and one for the secondary air system. I had to replace both of mine, they had both failed, my first indication is that my cruise control would not disengage every time I hit the brakes. Here is a picture of the switches I used to replace the original Nason switches.

They are air actuated switches, they are mounted to the brake treadle valve on the firewall, the valve needs to be removed in order to change the switches, I didn’t have to break any of the air lines, I had plenty of room to get the valve to where I could work on it. If you are having the same issue as I did, you have 2 bad switches, if one is still working you won’t see any issues. The switches are a pressure range of 4 +/- 1 PSI to activate, they are a N.O. Circuit. The original switch loosk like this one, it has 3 wires, but only 2 are used.

One is the primary system the other is the secondary system. My first indication something was wrong was my cruise control wouldn’t disengage when I pressed the brakes.

I had this issue with my 08 Endeavor last year, it turned out to be bad brake light switches, both the primary and secondary switches were bad. The switches were the Nason switches, but they were $$$ and a long wait time, I was able to get “generic” switches used by the trucking industry at NAPA. I did have to remove the treadle valve from the firewall to replace the switches, but with 2 people it was only about an hour or less task.

Totally different material in my 08 Endeavor

Steven P I like your dash panels, did you make them or did you find an after market manufacturer?

Just got mine yesterday, charging it now.

I found mine on the base of the drivers seat.

That’s exactly what I did.

The newer Monaco’s just use 1 set of switches for both Cruise and brake lights.

Tom The original switches have very similar pressure specs, I believe they were 4 +1, -0 to actuate. I don’t have the switches any longer, but I did verify the pressure specs of them before I started to find a replacement. The original switch is a Nason SM-1C-5R/WP205, see the attachment for the P/N specs. The switch I used is a BE13250, it is rated as a 3 to 5 psi actuation. The switches are a backup of each other, they are wired in parallel, guess it must be some kind of DOT regulation for vehicles of our weight, if you look at air diagrams for OTR trucks, they also have 2 switches, unlike our passenger vehicles. The 3rd wire on the switch is not used, the vehicle side only has 2 of the wires in the plug, also verified on the chassis schematic. Hope this all helps Tom, let me know if you need more info.

I couldn’t get mine out without removing the treadle valve from the firewall, it’s not to difficult, but makes replacing the switches possible (BTW, it’s a 2 man job, 1 inside and 1 outside) I pulled the dash out so we could get to the nuts easier.

On my coach, both switches were bad, maybe one a lot earlier than the other, but they are redundant, so if they both go out, no brake lights. My 1st clue that I had an issue is when my cruise wouldn’t disengage with the brake switch. Both switches had similar failure modes, if the brakes were applied slowly, they wouldn’t work, but if I pressed them very aggressively, they would work as well as disengage the cruise.

Ken Only 2 of the wires are used, the NO contacts, if your existing switches have enough length, you can cut off the wires and put on a couple of lugs for the new switches. You can see which wires are used, the harness on the coach that they plug into should only have 2 wires on it. Dennis

I just went thru the same issue a couple of months ago. Those switches are difficult to source, I ended up replacing mine with readily available brake switches as used in commercial applications, I got mine at Napa (P/N MBI BE13250) for about $37 each. Here is a picture of my switches installed. The original switches take a 1” wrench to remove and a lot of torque to break loose, I had to remove my treadle valve from the firewall to change the switches, I had enough length on my air lines so I didn’t have to disconnect them. Dennis

For those that are worrying about a valve that could get damaged, I use one of these, no external valve handle to flip open and very low profile protruding out of the pan. https://www.femco.com/products/

I guess 1 strike against the WFCO T57 is that it has a plastic case like the IOTA, the innards may be robust, but a heated condition or fire will go right thru the plastic. The ESCO/LYGHT unit is steel, worth the extra cost IMHO.

I just replaced my switch yesterday, kind of a PITA, the location of the wire harnesses is totally different between the IOTA and the LYGHT. I had to pull the GEN and Panel harnesses back thru the rear compartment wall and enlarge the existing holes an switch locations of the harnesses. Took about an hour and a half, but it’s done.