VFD CTIS Problems

[Bowmanvolfire]

Hello Forum:

We have a 1990 BMY that we have built into a brush truck. The truck is great. However, the CTIS is not. At this time the truck is out of service due to this system allowing multiple tires to go completely flat. This is even after we have disconnected the control head in the cab, which we assumed would place the system into run-flat and isolate each tire.

Please, point us to any threads on this forum that would discuss step by step instructions on how to get rid of this system.

If there hasn't been any detailed threads can someone please provide some guidance?

Thanks so much for the help.

John
Chief, BCVFD

 

[Warthog]

Welcome to the site.

Hopefully a member with CTIS experience will be along shortly.

Have you downloaded the free technical manuals for the truck?
http://www.steelsoldiers.com/showthread.php?79228-TM-s-for-the-939-series-trucks

 

[Warthog]

http://www.steelsoldiers.com/showthread.php?117453-Steps-to-remove-CTIS-on-the-M923a2
http://www.steelsoldiers.com/showthread.php?123315-What-size-plug-is-used-on-Rear-wheel-CTIS-removal
http://www.steelsoldiers.com/showthread.php?112032-removing-CTIS-from-927
http://www.steelsoldiers.com/showthread.php?105463-M923-CTIS-problem-help-please
http://www.steelsoldiers.com/showthread.php?121341-Leaking-Wheels-with-CTIS

 

[ke5eua]

John, can you hear the air escaping after the truck has been shut down? Which tires, are they on the same axle or different? When the controller is plugged in does it operate at all or just flash?

You're 2 1/2 hours north of me. If you can't get it straight or there isn't a closer member I'll pack the tool box and come give you a hand with it.

 

[hklvette]

If you're going to use it as a brush truck, it may be worth your while to fix the CTIS for off-road use. Until then, http://www.thosemilitaryguys.com/ctis-delete-kit/

 

[Bowmanvolfire]

Thanks for Warthog for the welcome and the discussion links. We have downloaded the manuals, we are working our way through them! Sgt Hopwood-thanks for your reply. Here are the "symptoms" for everyone to consider. The system does throw air in the tires while in highway mode. The controller did not flash, it stayed with the option pressed lit only. However, we have had an incident where it seems like the system deflated the tires down to around 40 psi still in highway mode. So, we disconnected the control head to put it into run-flat. We have had to constantly, manually put air into the tires. When each individual tire reaches around 60 psi it sounds like there is air leaking off somewhere and it will not allow the tire to go any higher in psi. At this time the real problem tires are the set directly behind the cab. They leak off to about 25 psi while sitting. We really need to get rid of the system altogether as we do not have the time to mess with it. Also, as the truck is going to be used as a brush truck there is concerns that the plastic lines might melt leaving us with a real problem in the field. Henry-thanks for link. Thanks again to everyone for their input. We appreciate it.

 

[8543BOB]

Good morning, i have a similar problem with the left front tire on my bmy m929 a2. The tire goes flat while sitting, i use an external compressor and same as above, the tire goes up to 60psi and like bowmanvolfire stated, i get the sound of air leaking off somewhere. The control panel shows just the hwy light flashing. I too would like to get rid of the entire system. How do i do that? When airing up the tire, is it best to use the valve on the outsied of the rim or inside?? Thanks bob

 

[Fredo Corleone]

The valve stems on each rim have two ports one is for manualing inflating the tire just like a car or bike with a Schrader valve. The other port has a hose that connects to the CTIS system with no Schrader valve. Air down the tire remove the CTIS hose install a Schrader valve then reinstall the CTIS hose, you may need to remove the tires from the truck to do them. No air can enter from the CTIS now but it also can't leave.

 

[Fredo Corleone]

The air lines feeding the axles are braided so they should be fine to leave. The plastic issue with fire I don't think you can get away from that as most of the air brake lines are modern plastic lines.

 

[8543BOB]

Good morning, i blamed the ctis for the left front tire loss of air, it had the same symptons as bowmansvolfire. Yesterdat with the temps at around 40 deg, i got the soapy water spray and found the leak at the rim seal. What a relief. Just thought i would let you all know. Thanks bob

 

[dawico]

The valve stems on each rim have two ports one is for manualing inflating the tire just like a car or bike with a Schrader valve. The other port has a hose that connects to the CTIS system with no Schrader valve. Air down the tire remove the CTIS hose install a Schrader valve then reinstall the CTIS hose, you may need to remove the tires from the truck to do them. No air can enter from the CTIS now but it also can't leave.

You shouldn't have to remove the tires to do this. It is pretty simple but yes, hook the hoses back up after you add the valves.

 

[Bowmanvolfire]

Hello all-we will be removing the CTIS system and using the kit from Those Military Guys. They will even buy the parts we take off the truck during the process!

 

[Fredo Corleone]

Wow! Glad they could help you out.

 

[Bowmanvolfire]

Those Military Guys were great. Very 5 ton smart. Highly recommend them.

 

[Fredo Corleone]

Just a happy customer. Good job TMG's

 

[Speedymoto]

I just fixed my CTIS system, I removed it totally! Beyond that, remember these trucks are old, the valve stems may leak and the O-RING around the outer ring is most likely leaking also, some of mine were! I even went a steep further, I took the old valve stems off , welded the hole on the rim, drilled new holes, and replaced them with common semi valve stems. NO more problems! You can of course buy the original valve stems so you do not have to drill new holes, the reason I did all of this, is to make it much easier to get common parts any where. It is a lot of work, but my problems are over! My truck was totally rebuilt in 2012, but what you find is it is not TOTALLY rebuilt, but I must say, pretty darn nice! thanks Tom. One more thing, Those Military Guys, have a kit too plug up the holes left behind, when taking off the CTIS system.

 

[Speedymoto]

I just fixed my CTIS system, I removed it totally! Beyond that, remember these trucks are old, the valve stems may leak and the O-RING around the outer ring is most likely leaking also, some of mine were! I even went a steep further, I took the old valve stems off , welded the hole on the rim, drilled new holes, and replaced them with common semi valve stems. NO more problems! You can of course buy the original valve stems so you do not have to drill new holes, the reason I did all of this, is to make it much easier to get common parts any where. It is a lot of work, but my problems are over! My truck was totally rebuilt in 2012, but what you find is it is not TOTALLY rebuilt, but I must say, pretty darn nice! thanks Tom

 

[Blackmagic94]

I don't understand why everyone removes the system. The ctis is awesome when it works. And not sure on the 5 ton but the fmtv trucks the highway mode stops filling air at 60 psi.