The things I learned while rebuilding my CTIS

[tommys2patrick]

Would you say that overall the CTIS is worth its weight if you drive in a variety of road conditions? If you do get all the parts working properly how long would you expect it to stay that way before things go South on you?

 

[Plugugly]

See my third post. Inflate all of the tires to the same pressure (30psi is enough) and try to run the CTIS unit without pressing any buttons. If they deflate, most likely a hub seal is to blame. If you get five lights, you have a large leak upstream of the wheel valves that needs to be fixed first.

Also, an update:
Based on what I've seen in my CTIS, I can say that the tires will self-balance their pressures as long as the system is in good working order and the pressure delta is low. If there is ~>15psi in the control manifold, the QRVs will stay closed and allow air to flow in both directions as long as the volume is low due to the design of the Quick Release Valve.

Thanks for the tips, and after a long phone conversation with Andyrv6av8r I've got somewhere to start. I already have all six tires inflated to 70psi, I did that before I ran out of time to work on it. Andyrv6av8r's suggestion was to unplug the controller and then try to see if it works normally again before trouble shooting the system in a more step-by-step way.

My truck has shown signs of a hub seal leak like a long honk after it sits for 30 minutes after running it, but not really any other time. Really rarely I'll get the five flashing lights, but only if it's sat a really long time. Most days, it's flip the switches and go after a "normal" flashing HWY to solid HWY in a few minutes from cold. Intermittent problems are my least favorite kind, but with the tips I'm thankful for maybe I can chase this down more tomorrow.

 

[Plugugly]

Alright, I have a driver's rear hub seal out. to clarify my symptoms in my first post, ALL my QRV's were leaking, I only thought the front one was. So the system would try to make HWY but the air was escaping out the QRVs. I was able to locate the offending hub by airing all 6 tires up to 70psi, then running the truck and going wheel to wheel after it was up to pressure and the system was trying to fill the tires. When the solenoids open in the cab and try to flow air, the leak would stop becasue the qrvs would close. It didn't leak down sitting because the QRVs would also close. But when the system was working (after hitting 120psi, and until it dropped below 85psi) it would open the wheel valves and I could hear/feel air rushing out all the QRVs, and also the brake drum on my drivers rear. The vent on that axle didn't look oily as others have said ight be an indication of a leak, but mine seems to have happened all at once, so that may be more of a long term indicator.

So, I guess I'm looking for right ups on fixing a hub seal. Of course, I'll look at the TM's to start, but I like real world experience and videos if I can find them too.

One quick question to verify, If I need the truck until I can get it fixed, if I unhook the big plug on the CTIS controller and air my tires up individually it should be safe to drive? The only time I have leaks is when the CTIS is trying to work. I have some construction stuff going on and may need to make a 20 mile trip to the lumber yard.

 

[Coffey1]

Yes unplugg the ecu with power off.
And if there's no leaks at wheel valve's your good to go after your air all tires the same.

 

[Plugugly]

Thanks, it's good to confirm. I probably won't run it that way too long, if at all. Just good to know I can move it some if I have to. I wouldn't want to depend too much on all the wheel valves to keep my tires up.

 

[Coffey1]

I have to fix a front right hub leak.
Looking for the Tm for it now.
Might take a while not very good at searching.
I have that line plugged off and system works
But will have to keep an eye out on that tires pressure

 

[hklvette]

Would you say that overall the CTIS is worth its weight if you drive in a variety of road conditions? If you do get all the parts working properly how long would you expect it to stay that way before things go South on you?

I would say if you're off-road >50% of the time it is worth keeping. The biggest problem that I see with it is the long increase from cross-country to highway modes and the stress that places on the truck's air system.

 

[Alexsha]

Upgrading your air dryer to the mrap version and maintaining your compressor helps to build air faster. I would think that shouldn't stress the air system too much as every time you start your truck you're filling the tanks. Stop and go traffic might be more of a stress.

 

[grayparatrooper]

Looking at an a2. He said the system works intermittent. Sometime he unplugs the controller plug it in and it works fine for awhile. Not much info I know but how hard is it to make the system work reliable? Also are there any places that could service the system?

 

[MtnSnow]

Sorry but the CTIS system is not a system I would consider reliable in any long term time frame. We have almost 25+ years with the system and they still fail regularly. I ran it on my M923a2 for over a year (1200 miles) and during that time I replaced 2 wheel valves, 1 QRV, 1 air separator (under the dash) and 1 pressure switch and of those 1200 miles less than 50 of them were dirt roads and all at different times!.... Ended up pulling it as well as the system on my M925a2 (which I had owned less than 3 months) and sold off the majority of the good working parts to others that needed to replace/fix their systems.

 

[grayparatrooper]

Sorry but the CTIS system is not a system I would consider reliable in any long term time frame. We have almost 25+ years with the system and they still fail regularly. I ran it on my M923a2 for over a year (1200 miles) and during that time I replaced 2 wheel valves, 1 QRV, 1 air separator (under the dash) and 1 pressure switch and of those 1200 miles less than 50 of them were dirt roads and all at different times!.... Ended up pulling it as well as the system on my M925a2 (which I had owned less than 3 months) and sold off the majority of the good working parts to others that needed to replace/fix their systems.

What all is involved in taking out the system? Can you leave it in and just cap it off somehow?

 

[MtnSnow]

What all is involved in taking out the system? Can you leave it in and just cap it off somehow?

It can be accomplished pretty easily with a kit purchased from "Those Military Guys" which will allow you to pull all the lines/wheel valves/QRV's/PCU & ECU and the wiring harness and not worry about any contaminates getting into the wrong places or if you have a good hydraulic supply house near by you can purchase the correct sized plugs for doing the work for a small savings.

You can actually leave everything in place and just unplug the electrical connection to the ECU (the controller on the shift tower) and just place a shrader valve (valve core) in the actual tire valve stem which would eliminate any bled down from a faulty wheel valve

 

[Coffey1]

Why delete it they are great to have.
When I have to go through my wet soft yard air down and it leaves little to no tracks.
I don't have to worry if tires have proper air pressure.
If I have tire leak from puncture run flat will keep it up.
Its a great system once you figure out how to work on it.

 

[aw113sgte]

Wondering if anyone can describe what's in Eaton PN 599913 rebuild kit?

 

[Duffysguns]

My right front tire on my LMTV looses air slowly so I gave it the soap water test and fond it leaking on the manifold end that connects to the tire fill side. When comparing to the other wheals I noticed that there are two different styles of this connections The one that's leaking is larger and has a slot for a flat head screw driver and when turned would have two positions. I have not been able to find any information on what that's for? Any help appreciated.

 

[hike]

My right front tire on my LMTV looses air slowly so I gave it the soap water test and fond it leaking on the manifold end that connects to the tire fill side. When comparing to the other wheals I noticed that there are two different styles of this connections The one that's leaking is larger and has a slot for a flat head screw driver and when turned would have two positions. I have not been able to find any information on what that's for? Any help appreciated.

The front tires have a different 90º angle connection with the slot so that the front tires may be lowered independent of the rear tires for air transport. If you do not need to air transport your vehicle it is considered good practice to replace these kneeling valves with non-kneeling valves. I believe @TomTime has some for sale here on the forum–

 

[TomTime]

MD - CTIS Right Angle (90 degree) Connectors, And Straight Thru Adapters

I have 10 8 6 used Dana Spicer CTIS right angle, 90 degree, connectors (part number 673240) left. These replace the kneeling valves on the FMTV's which were problematic. Also may fit other applications. I also have 2 used Dana Spicer coupler assemblies (straight thru adapters, part number...

www.steelsoldiers.com

 

[Lostchain]

My right front tire on my LMTV looses air slowly so I gave it the soap water test and fond it leaking on the manifold end that connects to the tire fill side. When comparing to the other wheals I noticed that there are two different styles of this connections The one that's leaking is larger and has a slot for a flat head screw driver and when turned would have two positions. I have not been able to find any information on what that's for? Any help appreciated.

As others have said, that is the kneeling valve for air transport. Mine is leaking just like yours right now and I am patiently waiting for non kneeling valve 90s to show up from @TomTime so I can fix it. Unless you plan to air transport your truck or maybe get it into a low garage, you can safely delete those.

 

[Duffysguns]

So now I have my leaks fixed and tested my CTIS and it cycled through the setting deflating and inflating the tires. Road test went well parked it and there was air releasing from the vent located above the rear Dif. It basically let the Passenger rear tire go flat. I inflated the tire with an external air supply and the tire holds air fine. On another road test, Light solid on CTIS controller no problems parked the truck and air again releasing from the rear vent above the Dif. Inflated the tire held air, disconnected the CTIS control box Road test parked tire still holding air, only the one tire is affected by this issue. any Ideas as to were the problem is?

 

[aw113sgte]

So now I have my leaks fixed and tested my CTIS and it cycled through the setting deflating and inflating the tires. Road test went well parked it and there was air releasing from the vent located above the rear Dif. It basically let the Passenger rear tire go flat. I inflated the tire with an external air supply and the tire holds air fine. On another road test, Light solid on CTIS controller no problems parked the truck and air again releasing from the rear vent above the Dif. Inflated the tire held air, disconnected the CTIS control box Road test parked tire still holding air, only the one tire is affected by this issue. any Ideas as to were the problem is?

Did you fully rebuild the wheel valves?