LMTV CTIS does not deflate

[MtnSnow]

I am surprised no one has mentioned it yet but make sure there is NOT a valve core in any of the wheel's valve stems.

 

[Konichiwa512]

Is that how the Army mechanics disable the CTIS? I deflated one tire by removing the schrader valve from the wheel valve. If the tire had an additional valve core in the tire I think it would not have deflated then. Should I check each tire? Would one tire with an extra valve shut down the whole deflation system? I think I can check just by releasing a little air from the schrader valves on each tire's wheel valve. It's worth a try to make sure.

 

[MtnSnow]

Yep by putting in a schrader/valve core in the wheel stem is how they disable the CTIS and make airing up and deflating a manual process. (besides sometimes uncoupling the wiring harness from the CTIS ECU)

And Yes by having one or more wheels with schrader/valve cores in place can create all kinds of havoc with the CTIS system

 

[Suprman]

I don't believe you can do that with the lmtv wheels at least not the ones with the large elbow off the valve stem.

 

[KRedd]

View attachment DANA CTIS Troubleshooting.pdf

 

[KRedd]

View attachment 545-3 CTIS Wheel valve filter.pdf

 

[Suprman]

I have been taking apart some ctis valve and wheel assemblies it would seem the majority of the wheel valve stems can accept a schrader valve. You have to take the air hose off first then the adapter piece and then unthread the elbow to expose the valve stem. Some of the wheels have a hose with elbow that appears to be crimped on. I havent done anything with these but I believe the stem underneath to be the same.

 

[Konichiwa512]

LMTVs have a Schrader valve as part of the wheel valve assembly. If there were another one in the tire the one on the wheel valve would not release pressure, which mine does. This weekend I replaced the manifold valve assembly with an expensive new one. CTIS still does not deflate and I still have three solid lights on the control box. I have no choice now but to get out the manual and start the troubleshooting process from the beginning. Again.

 

[Suprman]

Sounds like bad wiring or bad ctis controller. When you first power on the truck do the 3 solid lights come on immediately with no flashing lights?

 

[Konichiwa512]

The controller and writing harness are new too. I tried those last Fall.

 

[Suprman]

The manual does not offer a solution for 3 solid lights. Just looked. One thing you can try is metering out the switch on the end tank see if it closes at 120psi. Take a gauge and see if you have 120psi at the cab valve body. Thats a strange issue.

 

[Konichiwa512]

The schrader valve on the wheel valves can release pressure from the tires, but loosening the screws on the wheel valves does not. i disassembled one of the wheel valve and it looked brand new inside so I doubt it is malfunctioning. i don't know enough about CTIS to list all the possible causes for the wheel valve screw not being able to release pressure, but one of those possible causes is the problem. Something is preventing the low press air from being routed to the tires.

 

[Suprman]

With 3 solid lights on the controller it's probably not sending commands to the valve body

 

[coachgeo]

How goes your battle on this? Looking at purchasing an LMTV and the owner says CTIS is not operating (but wheels stay inflated to proper pressure)

Can you kindly PM me about where you've been able to get parts for CTIS

 

[coachgeo]

Found this in another thread on reprograming the M939 CTIS. It is Dana's trouble shoot manual for the system. Maybe it can give you a hint toward your issues. I don't know who makes the CTIS for the 1078

http://www2.dana.com/pdf/AXTS-0015.pdf

 

[Suprman]

I have all the lmtv ctis parts

 

[coachgeo]

This fellow ( http://www.steelsoldiers.com/member.php?70603-tjhuffy ) just axed the CTIS control module and built his own CTIS controls with solenoids. Am trying to twist his arm to posting up what he did. Hopefully, he will cause it sounds like a solution to many of the issues with this system.

 

[Suprman]

It's not hard to fix

 

[Konichiwa512]

Mine still doesn't deflate. New controller. New wire harness. New manifold valve assy. Very expensive parts but they didn't change anything. I met a guy at the Phoenix MV show who was working on a circuit board which would read the CTIS fault codes without the $700 computer gizmo from Spicer. Maybe that would help, but until then I am out of ideas.

 

[coachgeo]

Mine still doesn't deflate. New controller. New wire harness. New manifold valve assy. Very expensive parts but they didn't change anything. I met a guy at the Phoenix MV show who was working on a circuit board which would read the CTIS fault codes without the $700 computer gizmo from Spicer. Maybe that would help, but until then I am out of ideas.

Talked with TJhuffy about his eliminating the CTIS computer setup. He hopes to do a write up soon. Maybe it will help you and others. He does state that his works fine but how it is plumbed into the cab and where things sit is temporary. He plans to redo it in a more final location later. Hopefully he'll post up a thread on it soon.

Here is his description of what he did that he PMed to me.

I removed the air valve from under the passanger side of the dash, connected the air supply line to a gate valve (1) on the inlet side of the air regulator. Coming out of the outlet side of the regulator I installed a tee. On one side of the tee install a gate valve (2) to atmosphere, the other side conect to the supply line to the axles. To air up tires open gv1 set regulator to desired psi making sure gv2 is closed. Once tires have reached desired psi, close gv1 and open gv2 quickly. This will allow the individual tire valve to close holding pressure at the tires, and the air will blead off the axle seals.

To lower the tire pressure, close gv2, open gv1, set requlator at a value higher that the tires have in them. Once air starts going into the tires, open gv2 slowly while closing gv1. This will alow the air to blead back slowly causing the quick release valves to open dumping the tire air. Lower the pressure lower than desired, (not all tires will equalize the same when lowering pressure) close gv2 open gv1 and set regulator to desired pressure. Once pressure is reached, close gv1, open gv2 quickly and tire valves will seat again. Hope this helps and makes sence. If you would like to discuss over the phone send your number and a time that is good to call.

tjhuffy