Low air pressure light/buzzer inop on M923

[Rifleman]

Andy, there is a special tool that allows you to slip it in between each lead and the cannon plug. This Enables you to depress the prongs on each lead that locks it into the cannon plug to remove the leads from the plug without doing any damage. If you Goggle cannon plugs you should be able to find a vendor that lists the plugs and leads but also the tool to remove them too, or if you have a Fry's Electronics Store close by where you live you might be able to find the tool there.

 

[TexAndy]

something like this?

http://www.youtube.com/watch?v=8x726blInR8

Now I just need to figure out what size pins these are.

 

[Rifleman]

Andy, yes that's the tool. Remember when you resolder the leads that you use the right type of flux, you want to use rosin core flux for electrical repairs, DO NOT USE ACID core flux, it's used for plumbing repairs only. Please keep us posted on the outcome of your repairs and i hope my ideas have helped you.

 

[Artisan]

The engine temp deal....To the best of my knowledge it gave erroneous readings and it was deleted by cutting the wire and I think grounding it to the firewall. Look up there and look for the temp switch then look for the 35 wire and where does it go? I HAVE A THREAD SOMEPLACE ON THIS. Yes the cap on the dash is solid painted and usually no bulb inside. I await a new FWCM. If THAT fails I will do what I need to do w/ the cannon plug. NOT fun. I will leave the driver seat OUT till I am assured. it is a tough job to work on that cannon plug and I can not se how it comes apart either.

 

[Artisan]

CLICK HERE for a 35D wire thread from the past. CLICK HERE for a cannon plug thread from the past. I hope I am not muddlin' up your thread but just maybe between the two someone will find a resolve. I have been thru all this and go so frustrated I just moved on to other deeds.

 

[TexAndy]

The plug (the part with the wires from the harness going into it) is serviceable, but you need the Jonard insertion and extraction tools. Which I found for about $45 and $49 apiece on allied elec. They come in three different sizes from largest to smallest: R12, R16, and R20.

Going to go to the truck in a minute with some digital calipers and see if I can determine on google what size tool is needed.

I don't think you can service the half of the plug that is built into the FWCM.

 

[Artisan]

FWIW I just found the part number for the connector that attaches to the FWCM.
On PDF page #815 of tm...24P-1 , part #38. Scroll up to see the harness.
Here is the poop;
5935-00-622-2830 96906 MS3456W18-1S CONNECTOR,PLUG,ELEC

Now to try to find a HOW TO DISASSEMBLE / ASSEMBLE the deal as I have it, all made up.

 

[Artisan]

Again, FWIW, I think I found that connector and it looks like it comes w/ a TOOL! I can not link to it here because it is on EBAY. I will PM it to you Andy. I went ahead and bought one, I think I read he has more. Go look at this.

 

[TexAndy]

Using my multimeter to measure resistance:

One lead on the copper grounding connector coming out of the FWCM and the other lead on socket J (wire going to air light), resistance reads consistently over 125k ohms.

Same ground point, other probe on socket G, inconsistent results. resistance anywhere from 35k ohms to 400k ohms. This is the parking brake light socket.

This seems consistent with the trouble I'm having. My parking brake light only works some times. Air light has never once worked.


On that kit, are you sure that's the correct size? On my stock plug, it has "cannon-18 or cannon-16" stamped/cast on it. I can't tell if the number is 16 or 18, it's too small and my eyes are too bad. The style appears to be correct. eta: Ah, nm. I see, it's listed in the -24P parts lits. Cool.

 

[Artisan]

Its the same exact number...if wrong I blew 22 bux!

 

[TexAndy]

Actually, ours is MS3456W18-1S and those kits are MS3456L18-1s

I think that's a "class" difference. What that means as far as compatibility of the plugs/receptacles... I don't know. The body looks very similar to the one on the truck, aside from paintjob. The pins and sockets it comes with should be compatible at any rate. And the tool/s

 

[Rifleman]

TexAndy, i think, but i am not sure, but the class difference may be the way the male and female ends fit together. Some cannon plugs i have worked with had 3 index pins on the side of the outer housing for the female plug and only require a quarter turn to lock the male and female parts together. The other type of cannon plug the female plug has an index rib on the inter shell of the plug and the two parts then screw together. The latter type is what is used on our trucks, the former type is used on some commercial electronics equipment now.

 

[Artisan]

I just received my NIB, $149.00, including ride, FWCM from Alex at IdahoMotorPool. It is of a newer design I have never seen. The box is all plastic. The shape is a little different then normal (my normal anywho) . I sprung for it because it is about $65.00 cheaper then the "going rate". I plugged it in and the brake and low air lights lit up like Xmas morning. The brake light goes on and off when applied and the low air light shuts off about 60psi and will come on again if you bleed down to about 60. I think I am done w/ this exercise. If I were a rich man I would have bought this device sooner. I think I am done now. The cable end I got from ebay created more questions then awnsers, for me anyways. Oh, the box is plastic so I used a star washer and mounted the ground wire behind the plastic mounting tab.

 

[TexAndy]

The cable end kit came with an extraction and insertion tool for the pins. I haven't been able to figure out how the extraction too works, yet...

Sounds like your FWCM was faulty. If it was plug wires with bad connections, I don't think a new FWCM would have helped you.

I'm betting, based on how many people have this problem, that I have a similar issue. Before I replace it tho, I'm going to try re-doing the two relevant plug connections and see if that will fix it. If not, I've got the circuit all worked out for a home-brew failsafe warning control module. Shouldn't cost more than about 20 bucks in parts. 3 relays, a piezo buzzer and a project box will do it. If I end up doing that, I'll post a few pictures of course...