I want to take off the CTIS on my newly purchased 1990 M923A2

[Bluebeard]

I have spent several hours reading topics regarding the CTIS, but as of yet, have not found a step by step instruction on how to take the system off. I have one tire that continuously goes flat, yet there are no leaks on the tire. I will most likely use the truck only with the tires filled up to the max as I am carrying 1600 gallons of water and will need the full fill for the weight bearing capacity, so having an option to vary the tire pressure is of no interest to me. Can anyone lead me to a link about to a step by step discussion on how to take the CTIS off?

 

[timntrucks]

i pulled all my stuff off.. now i need to close up the holes on the axles. i was told to take off the fitting, jb weld it up and reinstall it. holds up well .. i think ill try it

 

[tractors0130]

The outer holes in the axles for the air fill lines on the CTIS were the same size as hydraulic fittings with straight threads (on my truck), not tapered pipe threads. Go to a place that sells hydraulic hoses and fittings and buy the hydraulic plug fittings with a gasket to cap off the axle holes. I left all the CTIS lines hooked up under the truck and unplugged the controller in the cab in case the next guy wanted to hook it all back up.

 

[wreckerman893]

The holes in the axles for the air fill lines on the CTIS were the same size as hydraulic fittings with straight threads (on my truck), not tapered pipe threads. Go to a place that sells hydraulic hoses and fittings and buy the hydraulic plug fittings with a gasket to cap off the axle holes.

This is how I capped one axle when I had to do a swap. I got the fittings at NAPA and a hydraulic hose place.

 

[Bluebeard]

I may need to take a picture so I can figure out exactly what to do to what. I am going out of town tomorrow for the weekend, but when I get back on Sunday I will post a pic and maybe you can direct me specifically what to cap.

 

[wreckerman893]

Those fittings plug the holes where the hose goes into the back side of the axle and the hole where the CTIS fitting come out on the rim side.
You also have to plug the lines up under the truck that go to the manifold on top of the axle.

 

[70deuce]

Are you sure the leaking tire's rim O-ring is not bad? I had one tire that constantly lost air on my M936A2 and the problem was the O-ring between the rim halves. CTIS worked perfectly perfectly after that was repaired.

 

[Bluebeard]

How do I get to the O ring? (if you would explain it in the simplest terms - as Carnac has found out, I obviously have a learning disability. Where do I find replacements? The truck was rehabbed in 2011, so I would think that whatever the problem is, it is minor.

 

[MtnSnow]

You have to first take the tire and wheel off the truck (this will normally also deflate the tire completely if the CTIS was working) or remove the valve stem core to fully deflate the tire. Then remove the nuts on the outer ring of the wheel. Then remove the outer ring from the wheel/tire (this can sometimes be a biotch to do if stuck/rusted on to other half of rim & or tire) Once separated you will see/find the o-ring in question. Wire brush/sand the groove the o-ring fits into so that it is clean and smooth. Lightly grease the new o-ring and place into the groove. Reinstall the removed outer ring (of course making sure it's sealing area is clean and smooth) and then tighten back down evenly in a star pattern. Reinstall tire/rim combo onto the truck and re-inflate.

 

[Bluebeard]

Are you sure the leaking tire's rim O-ring is not bad? I had one tire that constantly lost air on my M936A2 and the problem was the O-ring between the rim halves. CTIS worked perfectly perfectly after that was repaired.

OK, I check it one more time. I plugged in the CTIS unit and started the truck and the truck's CTIS buttons usually immediately all start flashing, but when I pushed the "run flat" button, it started flashing along with the highway button. I started thinking "all right...". I walked around the truck and didn't hear any obvious air leaks and I was squirting my soapy water in all the usual places and no bubbles. I got back in the cab, and all the lights on the CTIS were flashing and when I tried to push the "run flat" button, nothing happened other than all the lights were flashing.

Now what? Take the wheels off an replace o rings? Any other likely place? Or just replace it and run normal pressures. Apparently all the tires have varying tire pressures, so I am not so sure it is working on any of them. Just my rear left keeps going flat after a few days.

 

[wreckerman893]

Just my rear left keeps going flat after a few days.

I had the same problem on my M927A2.

I took the truck to a big truck tire repair shop that also did tractor and log skidder tires.

They removed the tire, broke it down, replaced the O-ring and reinstalled it for 35 bucks.

It solved the problem and was the best money I ever spent tire repair wise.

Your mileage (and cost) may vary.

 

[Mike929]

I had the same problem on my M927A2.

I took the truck to a big truck tire repair shop that also did tractor and log skidder tires.

They removed the tire, broke it down, replaced the O-ring and reinstalled it for 35 bucks.

It solved the problem and was the best money I ever spent tire repair wise.

Your mileage (and cost) may vary.

Wow, that was definitely money well spent!

Did you let them remove the CTIS?

 

[Csm Davis]

Okay all of this is well and good but let me give y'all an alternative. Unscrew the line going to the actual valvestem and put in a valvecore and put in correct air here and then screw the line back on as your cap, leave everything else hooked up but the cannon plug on the back of the controller. Looks stock and doesn't leak easily undone.
Also check the rim for max air pressure I think this is what's popping O - rings it is less than what some trucks are marked on the fender.

 

[Bluebeard]

I am looking at the troubleshooting manual for the CTIS and it shows more displays than I have in my truck. All I have is 5 buttons that flash- nothing else. It looks like there was once something mounted on the dash. Do I have the whole system, or is it missing parts? The DANA troubleshooting manual shows more displays.

Are the "O" rings that need to be possibly replaced only used for the CTIS? If I plug up all the holes, do I still have to possibly get in there and replace that "O" ring? I've done business with the guys at Boyce Equipment and when I told them I got the M923, he laughed and told me to disconnect the CTIS. Should I even be screwing with trying to get it running, or just trash it, call it good and save my money?

 

[70deuce]

If the rim O-ring is bad the tire will not hold air even with all the CTIS ports/lines plugged.

 

[Bluebeard]

If the rim O-ring is bad the tire will not hold air even with all the CTIS ports/lines plugged.

Thank you for that........ I guess I will be replacing some O rings, either way.

Do you know if the CTIS came only with the buttons and no display? If it is all there, maybe I will take a stab at getting it working. if it isn't all there, then I will just plug the ports, replace the O rings and be done with it.

 

[hklvette]

I am looking at the troubleshooting manual for the CTIS and it shows more displays than I have in my truck. All I have is 5 buttons that flash- nothing else. It looks like there was once something mounted on the dash. Do I have the whole system, or is it missing parts? The DANA troubleshooting manual shows more displays.

Are the "O" rings that need to be possibly replaced only used for the CTIS? If I plug up all the holes, do I still have to possibly get in there and replace that "O" ring? I've done business with the guys at Boyce Equipment and when I told them I got the M923, he laughed and told me to disconnect the CTIS. Should I even be screwing with trying to get it running, or just trash it, call it good and save my money?

The answer on keeping the CTIS is "are you going to use it?" If you bought the truck just for cruising around town, its better to take it off. If you air down/ up frequently, it may be worth repairing the system. To be frank, the system isn't that complex but is a bit fickle about maintenance.

edit: The CTIS controllers that we have are the older units. The one that you're talking about in the Dana TS manual are the newer units as found in the MTVR and maybe FMTV (not sure about that one). The flashing lights described in the manual apply to the unit found in the M939 trucks.

 

[Bluebeard]

The answer on keeping the CTIS is "are you going to use it?" If you bought the truck just for cruising around town, its better to take it off. If you air down/ up frequently, it may be worth repairing the system. To be frank, the system isn't that complex but is a bit fickle about maintenance.

In reality, no we probably won't use it, I guess the aired down setting is for sand? The closest sand around here is 100 miles away and it will NEVER go there. Just another option I probably won't be using. I'll just disconnect.


One more quick question, since I have your attention. For the life of me, I cannot figure out how to "unlock" the lights on the dash. The manual just says "unlock them" ..........well, I have applied probably almost enough force to the lever to almost break it and it won't budge. What's the trick? I have no idea how to turn on the lights, so I guess I can't drive at night.

 

[MtnSnow]

Lift up on the bottom right lever to "unlock" while holding it in the UP position you can move the Upper right lever (headlights/stop & turns) or the lower left lever (dash lights/park lights)

Edit.....Ohh dont try driving it in the day either if you can't turn on the lights cause if you can't turn on the lights you don't have working turnsignals or stoplights etc..

 

[Trailboss]

One more quick question, since I have your attention. For the life of me, I cannot figure out how to "unlock" the lights on the dash. The manual just says "unlock them" ..........well, I have applied probably almost enough force to the lever to almost break it and it won't budge. What's the trick? I have no idea how to turn on the lights, so I guess I can't drive at night.

Lift up on the lower right lever while you move the top or lower left lever to the desired position. The lower right lever is the locking lever.