What would cause/allow all 6 tires to deflate when CTis is supposed to be inflating?

Hello,

I'm experiencing some difficulty with my CT!S system (M923A2)... What would cause/allow all 6 tires to deflate when CT!S is supposed to be inflating? Such as today, The tires where all above 50, still had 5 flashing lights from last time I drove it (That and today are only times I've had the 5 flashing code). I drove it 1 hr one way, then when I fired it up to come back, it reverted to HWY, single flashing light to inflate.... well... the tire pressured kept dropping all the way home. visible low in all tires when I parked it, and I went out after dinner and it's basically sitting on 6 flat tires . This is the second time that this has happened. The system used to work fine. I haven't had time to go through the "check every single part 5 times" WP0148 for the 5 flashing lights yet, but that code has gone away on it's own both times it came on anyway.



Can anyone suggest where I should start? -I mean besides breaking out the gladhand again.....

Thanks!

Disconnect it and forget that it ever existed. No really, disconnect it. The older CTIS is crap and will cause nothing but problems

What he said. The system lets more air out than it puts in.

Cap it off and be finished with it. I'd love to have ctis if I had a team of mechanics to keep it up.

I have two of my wheels disabled and my lights blink constantly.
CTIS was a good idea in theory but it was designed by an idiot and built by morons.
Unless you do a lot of off roading I would listen to the advice above.
I was in a trans unit years ago that had the 5 ton trucks with CTIS. There was one guy who was detailed to go to the Motor Pool every Monday morning and crank all the trucks that were sitting on flats because it pissed off the Commander if he saw them.
Several of the parts are made of a weak pot metal and will break if you get them in a bind when changing tires.
Parts used to be hard to get but other folks have posted that they are now available.

CTIS has two modes:

1. Malfunctioning
2. Disabled/removed.

You have a leaking hub seal. The system is sending fill air to the tires but with the large hub seal leak the fill air is mimicking the 20psi dump "signal" and your tire pressure is going down. Feel the rubber boot on each of the 3 quick release valves one might have some grease coming out that will help you narrow it down to an axle. The seals are cheap and available but you have to pull the axle to replace them its a lot of work. It happened to me on one of my trucks I just put schrader valves in the stems and removed the control and valve body. It gives the second passenger more foot room anyways.
Will

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wb1895 said:

Disconnect it and forget that it ever existed. No really, disconnect it. The older CTIS is crap and will cause nothing but problems

Click to expand...

The "older" CTIS?? Which ones are you referring to?? My '91 932A2 works great! (knock on wood)

Never heard anyone say they are always trouble free- everyone usually has lots of issues with them. You need the budget and the mentality of the military to keep them operational. Doomsday is using up his lifetime supply of good luck on his 932A2- when it runs out someday, and if he still has his 932 he will likely report grief with his CTIS system too! Unless you are going to be in constant combat situations where you need the air system to air up those bullet riddled tires until you can evacuate the combat zone- then they are just a constant irritation and source of problems.

I don't believe the ctis would help you with a bullet hole in a tire. Air would escape from a bullet hole much faster than the ctis feed could fill or keep up with the leak. The trucks are old and the military did not seem to put a priority on maintaining the ctis systems. If you replaced the entire ctis system seals and all then it would probably be reliable for some time but this is just not the case for most trucks. It falls under YMMV.

So I to am going through this ordeal too, I get unplug the controller simple enough, but how are you guys plugging the axles, tapping and inserting a plug "bolt" or a rubber plug (or even a cork!?!). I am interested apparently this is a common thing but never recorded, or that at least a dedicated SS and google search could find(maybe poorly worded). Just need to know how to plug and I'll post up what I did for a quick search for future CTIS "fixes".

Unplug the controller right by the transmission shifter. Go to your wheels, you will see where the air enters the wheel from the CTIS system. There are two inlets that enter your wheel: One on the interior and one the exterior of the rim face. The interior one is just a long secondary schrader valve stem. Remove the fitting on the exterior portion of that stem, once the fitting if off, you have a bare valve stem with no schrader valve....all you need to do is put an extra schrader valve into that stem...and DONE. In a pinch, you could simply remove the schrader valve from the CTIS valve if you did not have one handy.

I don't have CTIS on my M923 but some of the CTIS is still on my M932A2 parts truck. The more I see these threads concerning the problems with the CTIS, the more I like my glandhand air hose. I don't think I would want the system and if I had it I would keep it until it failed then remove/bypass system. JMHO

actionpaintball said:

Unplug the controller right by the transmission shifter. Go to your wheels, you will see where the air enters the wheel from the CTIS system. There are two inlets that enter your wheel: One on the interior and one the exterior of the rim face. The interior one is just a long secondary schrader valve stem. Remove the fitting on the exterior portion of that stem, once the fitting if off, you have a bare valve stem with no schrader valve....all you need to do is put an extra schrader valve into that stem...and DONE. In a pinch, you could simply remove the schrader valve from the CTIS valve if you did not have one handy.

Click to expand...

Thanks for the detailed instructions in case I have to go that route.

The CTIS was working fine prior to this, which makes me think it is likely only one component that needs to be identified and repaired / replaced. SUPRMAN, thanks for the suggestion, I will check that first.

If your times have gone flat several times, I would be cautious about running those tires at speed. I am not an authority on tires by any means but I think there are several threads about that you might want to check. Just be careful, it isn't fun when a steer time comes apart on you in traffic at 50 mph.

actionpaintball said:

Unplug the controller right by the transmission shifter. Go to your wheels, you will see where the air enters the wheel from the CTIS system. There are two inlets that enter your wheel: One on the interior and one the exterior of the rim face. The interior one is just a long secondary schrader valve stem. Remove the fitting on the exterior portion of that stem, once the fitting if off, you have a bare valve stem with no schrader valve....all you need to do is put an extra schrader valve into that stem...and DONE. In a pinch, you could simply remove the schrader valve from the CTIS valve if you did not have one handy.

Click to expand...

So the valves that are on the rim you left those alone and just disconnect them at the tire stem and put in a schrader valve? Is this what Im understanding?

You can do that. The ones I have seen that the military schrader valved have the valves inserted in the wheel stems. Like an A1 truck would have. Then they screw the hose back on and put it all back together and have to use the inside stem to fill or let down. It wouldn't be hard to make a plate to cover the front hub holes it could be held on by 2 hub bolts and the rear hub holes are threaded you could just buy a plug of sort and screw it in provided it didn't go too far and fall in.

Okay, thats what was hanging me up was I dodnt know the rears where threaded and then how to plug the fronts. To\o the shop now!

I don't have the CTIS system on my M925 but the advice that Triple C gave you about checking your tires is very good advice. Just 2 weeks ago i had a blow out on a steering tire and i have to tell you i still haven't been able to locate my seat cushion.

The thing we all need to remember is most of the tires on our trucks can be upwards of 10years old or older and having them deflate like what has happened to your truck is not good at all for the sidewalls of your tires and just an FYI the sidewall is what failed on my truck 2 weeks ago and it was 10 years old.