M925A2 CTIS and Tire Change

[sassriverrat]

Hey everyone. Thanks for reading.

I just went from 14R20s with perfect CTIS to 16R20 Michelin XZLs and the CTIS is not working.

I know the front right tire is leaking on the hose between the valve stem and controller (flexible piece- to be replaced tomorrow).


However- if I start up- the computer shows highway light and then after it takes a "slug of air," goes to all 5 blinking. I can restart and hit emergency or any other button and it'll still take a slug and go to five blinking. The slug of air sounds weak on discharge and if I hold a button when I first start, I can get a blink on that light and then a 5 light blink, alternating only if I hold buttons. Any ideas?

When I was changing boots and tires, I had paper towels in each hose mount on the frame and I feel as though she may have sucked in the paper towel on the CTIS plug because it wasn't there when I returned, but I don't think this system ever draws air in, right?

Thanks,
Austen

 

[fuzzytoaster]

5 lights means there's a serious fault that can't be overridden. Double check to make sure there are no valve cores in the valve stems first off. I assume you reused the "combat rims" off your 14's but didn't mention if you did the work or a shop did. If a shop did chances are they may have put in a core. It's one of the most common "CTIS IN-OP" issues even coming from the military.

 

[sassriverrat]

I did it myself. I do all my own work. But she sat for two weeks.

Do these trucks ever suck (vacuum) or just post pressure to the tires?

 

[Andyrv6av8r]

I did it myself. I do all my own work. But she sat for two weeks.

Do these trucks ever suck (vacuum) or just post pressure to the tires?

Pressure only.

 

[Andyrv6av8r]

Check all of your wheel valve connections real close. It may have a leak and is faulting out when it first does a pressure check.

 

[sassriverrat]

Ok so I have a very small leak on one fitting on the hose connecting the valve stem to the "valve" on the rim. I will replace tomorrow but would that be enough to fault it? Today when I drained air it made a weird sound either from the dryer or that after tank, I'll have to crawl under tomorrow. Almost like a gurgling.

On a side note- I guess brake shoes can only go on one way? My drum is wicked hot on the left front- I may have done those backwards.....

 

[Jbulach]

Ok so I have a very small leak on one fitting on the hose connecting the valve stem to the "valve" on the rim. I will replace tomorrow but would that be enough to fault it?...

Possibly,

Ironically these CTIS Systems don't like leaks. However, I'm betting you created a leak somewhere else, before the wheel valves.

If you push the run-flat button you should be able to get your system to work, that way you can start tracking air leaks while it's cycling. It's best if you can hook the truck up to shop air so you don't have to have it running and can hear the leaks easier...

 

[sassriverrat]

Roger. I will try again today on shop air. I couldn't find any yesterday. When taking a slug of air, it almost sounded like there might be a blockage on that end of it. Not sure. Never had this issue before changing the tires and boots on the front end.

 

[sassriverrat]

I can't get it to do a full cycle though, even on run-flat. She takes a single slug of air and goes into the 5 light blinking. After 15 minutes she'll go again and repeat. If I start and immediately hit the run flat button it still takes one slug of air and goes into 5 light blinking.

 

[Andyrv6av8r]

Are you sure that all 4 wheel valves on the rear are tight on the nipples coming out of the hubs, no leaks? Front wheel valves tight on the hubs with the o-ring in place? All hose fittings tight? It sounds like you have a big enough leak to fault out the system during it's initial pressure check.

 

[Jbulach]

Yep, sounds like you have a big leak or a bunch of small ones. Have soldier B push the run flat button while you go from wheel to wheel listening and feeling for air.

 

[sassriverrat]

Yep. I fixed the hose on the front right that I knew was leaking (between valve and stem). I haven't found another leak. Will attack again tomorrow with a spray bottle of dawn/water for bubbles. I guess it could be read hubs. I haven't really heard hissing anywhere. What I have learned:

1. It won't do a pressure check until secondary air makes it to 90
2. If I overfill a tire (I've tried on the fronts), I get 4 blinking, not 5. I hit run flat and I think it drains to match, then gives me 5 blinking. The pressure check exhaust dumps sound weak...not the usual nice big dump of air somewhere. They hardly make any noise almost. I guess to check tests tomorrow.

 

[sassriverrat]

I found one small leak around the threads of the left front tire fill hose going into the axle. Will remove and rap with either thread sealer or teflon tape. I don't hear any super loud whistling/siren sounds so I assume (pray and hope) none of the axle seals have gone. Two of the rear hubs (caps) dripped oil when I removed the rear tires (so two bolts were out, each) and although I'm not sure if they are pressurized, I will remove them and reseal. Keeping fingers crossed I can get this system back- I really like it. Does anyone have a place on the truck they recommend disconnecting so I can hookup shop and keep system constantly pressurized so I can search for leaks without "soldier b" and without getting only 2 second leak bursts?

Thanks!

 

[Andyrv6av8r]

I found one small leak around the threads of the left front tire fill hose going into the axle. Will remove and rap with either thread sealer or teflon tape. I don't hear any super loud whistling/siren sounds so I assume (pray and hope) none of the axle seals have gone. Two of the rear hubs (caps) dripped oil when I removed the rear tires (so two bolts were out, each) and although I'm not sure if they are pressurized, I will remove them and reseal. Keeping fingers crossed I can get this system back- I really like it. Does anyone have a place on the truck they recommend disconnecting so I can hookup shop and keep system constantly pressurized so I can search for leaks without "soldier b" and without getting only 2 second leak bursts?

Thanks!

Only way to keep constant pressure on the system is to remove the outlet hose from your PCU in the cab and apply regulated air pressure to it. I can't remember if it's the black or yellow one.

 

[Jbulach]

Should be the black one, or the one without the water trap in it...


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[Jbulach]

Also, for your wheel valve hose leak, you should replace the o-ring inside the swivel end instead of thread tape.


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[sassriverrat]

Ok Guys some more thoughts out loud-

I applied air and only got a small leak around the front right tire tire stem (o-ring inside leaking- will replace tomorrow). I can't find any other leaks. I also filled all tires in the neighborhood of 65PSI and the fronts a little harder. I restarted the truck with the system back together and it drained the fronts waayyyyy down after I hit "highway" because I had a 4 blinking light combo instead of five. Not sure why. Any new ideas? Still surprised since everything we perfect right before I put new tires on. Still wondering if the paper towel plug on the front ride frame-hose mount could have been sucked into the system.

ALP

 

[Andyrv6av8r]

You do understand that all of the tires are connected to one air line coming from your PCU and that it can't drain just the front tires? All six tires inflate and deflate together.

 

[Jbulach]

Ok Guys some more thoughts out loud-

I applied air and only got a small leak around the front right tire tire stem (o-ring inside leaking- will replace tomorrow). I can't find any other leaks. I also filled all tires in the neighborhood of 65PSI and the fronts a little harder. I restarted the truck with the system back together and it drained the fronts waayyyyy down after I hit "highway" because I had a 4 blinking light combo instead of five. Not sure why. Any new ideas? Still surprised since everything we perfect right before I put new tires on. Still wondering if the paper towel plug on the front ride frame-hose mount could have been sucked into the system.

ALP

Umm... is there any chance that you put valve cores in the valve stems on the rear wheels during the mounting process?

 

[Jbulach]

You do understand that all of the tires are connected to one air line coming from your PCU and that it can't drain just the front tires? All six tires inflate and deflate together.

Yes and no... only one air line, but six different wheel valves, that can act independently, depending on tire pressure.