M1078 fmtv ctis

[Mullaney]

Guess I am going to add to this CTIS thread. Got my rig delivered off a truck today. It seemed like the front red glad-hand was pissing air. Parked it so I could flush and drain fluids and see what's what. Tried to plug the glad-hand but it won't.... should the vents pop off at circa 120 psi?
All 5 CITS lights were blinking.
<30 PSI on front brakes
>120 PSI on Back brakes

Per Ohiobenz
QUOTE="Ohiobenz, post: 2151475, member: 86215"]
http://maintenanceprocedures.tpub.com/TM-9-2320-366-20-3/index.htm

Good info on CTIS in here...
Not giving up just yet.

I went there and I see they have a section of troubleshooting starting at 5 blinking lights. They instruct to check the manifold valve vent as the first item. Now this is a multipart question:
1: Is there a TM I should be looking at as well that will give an overview of the air system?
2: Is there a TM I should be looking at as well that will give an overview of the Electrical System?
3: Looking at the 3 tanks, which ones is the wet, dry etc?
[/QUOTE]
.
The wet tank is the one that has the valve on the back side of it with a bolt sticking out of the side of it.

The CTIS book (that I am aware of) for the S&S trucks doesn't exist in the standard TM format. Best fix for that is to find the DANA book on all things CTIS. There is also a Dana Diagnostic Tool that might be useful.

This should be useful though:

Dana CTIS Troubleshooting Guide (M900 series)

.

 

[GeneralDisorder]

Under normal operation there should be no air present to the front glad hands. They have one-way check valves that should only allow air to flow IN to the front glad hands. Never out:

FMTV: Get the Right Gladhand Couplings

Having problems with your FMTV brakes locking or the parking brake won’t engage or disengage? It’s possible the front service and emergency gladhands have the wrong couplings installed. Get the latest

www.psmagazine.army.mil

 

[GENX]

Under normal operation there should be no air present to the front glad hands. They have one-way check valves that should only allow air to flow IN to the front glad hands. Never out:

FMTV: Get the Right Gladhand Couplings

Having problems with your FMTV brakes locking or the parking brake won’t engage or disengage? It’s possible the front service and emergency gladhands have the wrong couplings installed. Get the latest

www.psmagazine.army.mil

Would this be the check valve tucked down below? The small plastic line at left feeds glad hand.

 

[GENX]

Would this be the check valve tucked down below? The small plastic line at left feeds glad hand.

Also seems odd the front brakes had < 30 PSI. Wonder if that check valve is what’s draining the system. I kept hearing the air canister by battery box discharge air periodically.

 

[Ronmar]

Yep the fronts are innies, but must be vented when not in use as a leak in the checks downstream can cause issues if that air is not allowed to escape thru the vented covers. The most likley place for a leak are the 2way checks under the drivers floor/behind the grill. The top one connects back to the red gladhand. The bottom two connect back to the blue gladhand…. Common problem….

that check in your pic is the one that feeds/charges the wet tank/air system from a towing vehicle. Tgat gladhand also feeds the top 2way behind drivers grill to allow the towing behicle to release the park brakes

the rear tank is the wet tank the middle one is the primary/rear brake tank and the front tank is the secondary or front brake system tank. Thh compressor feeds the dryer, the dryer feeds the wet and the wet feeds the pri-sec tanks.

ctis, fan, cab suspension are all tapoed off of the wet tank via a protection valve. They only get air if the wet is above 85psi.

the dryer(canister behind tanks) purges every time the system reaches set pressure and the governor cuts out/unloads.

since both pri and sec tanks are fed by the same wet tank, 30 psi on the front means a big leak or more likly a bad gauge sensor…

if it were a bad leak the compressor could never reach set pressure and purge the dryer…

 

[GeneralDisorder]

In your picture the check valve is to the driver's side of the T. This is the check valve:

 

[GeneralDisorder]

Yeah that 30 psi front reading sounds erroneous. The tanks are linked and for the front tank to be lower than the center tank by ~100 psi would require both a large leak and a restriction in flow from the center to front if I had to guess. The unloader on the compressor kicks in around 120 so that kind of indicates you are unloading and that would not likely be the case if you had that large of a leak.

OR more likely as Ronmar suggests - something amiss with the sending unit, gauge, or wiring displaying the pressure in the front tank.

On a side note - one of the things you should immediately replace is the glad hand seals. They are cheap and if you need to use the rear glad hand for air you want a good seal there. Most I have seen are shot.

 

[GENX]

I found a spreadsheet with parts list and it gave this check (shuttle type) for reference.

Advance Auto Parts - Down for Maintenance

I suppose it would be handy to have on hand if I don't change out. I wonder how hard it would be to delete the front so they don't introduce interference again down the road... I don't see being towed like the Military would do it.

 

[GeneralDisorder]

The check valve in your picture is a Haldex N13526BE

 

[GENX]

The check valve in your picture is a Haldex N13526BE

Thank you. I will try to swap the gauges and see if it's a gauge and check the voltages of each (If they work on Voltage.. LOL) to determine if it's a bad sending unit. I will keep ya'll posted. Appreciate the help, this doesn't seem so crushing anymore, ya'll are just amazing.

 

[GeneralDisorder]

I wonder how hard it would be to delete the front so they don't introduce interference again down the road... I don't see being towed like the Military would do it.

Don't be so hasty to delete stuff. These trucks breed like rabbits. Once you get one it attracts more quickly. Tow bars happen also. And if you make friends with the local reserve or national guard guys you may have a phone number you can call for a "recovery training mission" involving proper HEMTT wreckers and all kinds of fun and games.

 

[Ronmar]

A lot of times that single check you pictured and the 2way checks behind the drivers grill simply get crap in them, but more than likely they have some internal corrosion.. the air leaking from the red gladhand can come from either that valve or the 2way. Noting when it is leaking can give you a hint as to where. If it leaks all the time, probably that check below the gladhand. Drain the wet tank to confirm this, ifit is that check, it should stop with no air in the wet tank. If the top 2way is leaking out thru that front red emer gladhand, it will only do it when the park brakes are released/park air is applied. That single check below the gladhand is a PITA to access

I did a front gladhand delete video that shows the valves location and access pretty well. Look under youtube user rronmar. There is also a rear brake component video that you should watch if you are new to airbrakes…

so with your gauges reading 120 and 30 PSI respectively, is the buzzer going off? It should alarm when either air pressure sender drops below about 85PSI… The gauge senders/pressure switches are right at eyelevel when you open the drivers door…

 

[GENX]

Don't be so hasty to delete stuff. These trucks breed like rabbits. Once you get one it attracts more quickly. Tow bars happen also. And if you make friends with the local reserve or national guard guys you may have a phone number you can call for a "recovery training mission" involving proper HEMTT wreckers and all kinds of fun and games.

Yes! You know I was just thinking I might keep it, you never know, plus it might come in handy to make an input in case I need to feed the Wet tank and charge the system remotely in case of future failure.

 

[GENX]

so with your gauges reading 120 and 30 PSI respectively, is the buzzer going off? It should alarm when either air pressure sender drops below about 85PSI… The gauge senders/pressure switches are right at eyelevel when you open the drivers door…

Yes. But it eventually quit buzzing when we unloaded it and swapped drivers. When I got in, no buzz and I saw the pressure read around 120. Later I moved it to the sacred place of rehabilitation and that's when it decided to start fussing.

I will check out the youtube channel. Thanks for that.

Anyone know the part number on the 2way check valve perchance?

 

[Ronmar]

Well the pressure gauge sender and warning switch are in the same unit, so swapping gauge heads/sensor wires should help you narrow down which is acting up...

 

[GENX]

This should be useful though:

Dana CTIS Troubleshooting Guide (M900 series)

 

[GENX]

I ordered the Haldex 13526 BE at NAPA.
My wife picked up and I got the attached
Haldex 13526 AG.

Any issues going with this? The clerk didn’t say it was not going to be the same.

 

[Ronmar]

I ordered the Haldex 13526 BE at NAPA.
My wife picked up and I got the attached
Haldex 13526 AG.

Any issues going with this? The clerk didn’t say it was not going to be the same.

That shouldn’t be an issue as I believe it connects to a hose on one end. It is just a PITA to get to and wrench on it

 

[GeneralDisorder]

The letters likely indicate material composition. I wouldn't worry about it.

 

[GENX]

Check valve in and the PSI Guages worked and the low pressure buzzer worked. But still
Have 5 blinking lights on CTIS.
Do y’all think I should drain diesel out and put fresh before cycling the engine on and off?