M923A2 CTIS Problem

MarcM35A2

Member
98
0
6
Location
Wiehl/ Germany
Hey Guys, yesterday I bought my new M923A2. On my trip home I realized that the LED lights on the CTIS control unti are flashing all the time! And the CTIS system didn´t take commands for changing tire pressure. When I start the engine, the CTIS is checking the pressure. After that the leds are flashing. Have you any Idea what could be the problem???
Oh, the tires are still on Highway pressure........
Thanks for your help!!!
 

greenmonster

Member
119
2
18
Location
cody, wyoming
Ok so I am no expert I had a heck of a time diagnosing mine but this what has worked for me.

Get the system all up to pressure, Shut engine down and restart truck. Press the highway mode if it clicks then you hear some air moving in the valve body on the floor then the valves outside makes a noise and then all the lights flash.... it didnt see the feed back it was looking for when it check tire pressures mine does this when one tire is lower than the others. I have had good luck with just pressing the emerg and run flat buttons and letting it air down all tires then airing back up. When it drops down from the pressure it is at to the run flat it will equalize the tire pressures.

If when you push the button it just flashes and flashes then all five start flashing it is not seeing the correct pressure in the secondary wet tank. I had this problem and just jumper-ed the switch. the down side to this is there is a possibility, be it a slight one that the tires can be filling up and you can loose brakes. I have had this bypassed for a while now and it airs the tires up so slow that I have never seen my secondary pressure drop bellow 100psi when airing up the tires. Jump switch at cannon plug and see if system operates.

Mine if it sits for a while likes to be vented then operated so push run flat for five seconds or so let it blow some are out of the tires and valves then go back to sand or xc. I also like to drive it a little bit before screwing with tire pressures to much I have heard it helps keep axle seals from blowing out. It seems to help in speeding up pressure changes. I use mine alot it seems like the more I use it the better it works. When I go a week or so without using it, it gets kind of temperamental.

Good luck
 

NightOwl

New member
66
1
0
Location
Crownsville, Maryland
I had to drive my truck for 30 minutes or so before turning it off and running the procedures described by greenmonster. I also think raising the RPMs to 1,500 while in neutral helps keep the air pressure up in the tanks and helps somehow. I had one tire that was a little low and finally got it to inflate with greenmonter's steps and all the blinking lights went away. We'll see what happens tomorrow..
 

Gunzy

Well-known member
1,768
45
48
Location
Roy, Utah
I don't have CTIS, but the more I read or hear about it, the less I would want the system in anything. I see where a majority of guys simply disable the system altogether. I have an air hose that hooks to a glad hand, works fine and is reliable.
 

parcola1

New member
8
0
0
Location
wildomar, ca.
I just took delivery of a 1990 M923 A2. After a drive around the block, the front tires deflated well below normal highway operating pressure. The CTIS alarm sounded off and an annoying clicking noise next to the shift box starts when I fire up the truck. I can't get the front tires to inflate. Bad solenoid?.....suggestions or solutions?
 

Suprman

Well-known member
Supporting Vendor
6,744
170
63
Location
Stratford/Connecticut
There is no ctis alarm. If you hear an alarm it is low air or your brake is on. The click is the valve assembly sending air to do a pressure check. Are there any lights lit on the ctis controller. You may have to turn on the light switch to see them.
Will
 

ZZ4x4

Member
87
1
8
Location
Sachse, TX
I'm no expert but after working with my CTIS for a while, I've found a few things.
For troubleshooting, I would start by using the interactive repair program in the TM section which shows the various air lines and the function of each valve . After studying the inflate and deflate operations it makes more sense in troubleshooting.
One thing that is very important to note is what happens when the truck is OFF and parked. Do the tires stay inflated or do some leak down. If any of them leak down, you could disconnect the air line between the wheel valve and fill stem on the wheel. Then insert a standard stem valve inside the stem. Then wait. If the tire continues to lose pressure there is leak in the tire that needs to be fixed. If the leak goes away, the wheel valve needs to be rebuilt. Conversely you could follow the TM and disconnect the wheel valve from the hub ( still connected to the stem) and submerge in a bucket of water to look for wheel valve leakage.
When I picked up my truck from GL there was a stem valve hiding in the stem on one wheel with the wheel valve line still connected. This prevented the system from venting or filling the tire. Obviously done due to a leaking wheel valve. It caused the lights on the CTIS control to blink. Also the CTIS air filters at each wheel valve were completely clogged. Still looking for replacements.
 

TehTDK

Member
Steel Soldiers Supporter
577
19
18
Location
Denmark
I know the older CTIS implementations might be tempemental. But I asked one of my motor-mechanics when I was at the local army proving base and he said they hadn't experienced any CTIS issues on the JEERV's that we have here or on the Cougars in afghanistan. Downside however was that apparently most of the US armed forces tosses a tire when it goes bad and tosses on a new one complete with rim, CTIS assembly etc, while we have to take it all apart and put it all back together again and risk leaks.

I can see the usefulness of CTIS, IF and only IF it works reliably.
 

phxmark

New member
35
0
0
Location
Glendale, AZ
Hello Everyone. I am a new owner of a M923A2. I have got my CTIS to work by bypassing the pressure switch under the vehicle and tightening the fittings on the front wheels. The pressure switch seems to be bad.

Question is, where can I get one of these pressure switches. It has a canon plug attached to the wires that come off it.

Thanks in advanced,
Mark
 
Last edited:

Suprman

Well-known member
Supporting Vendor
6,744
170
63
Location
Stratford/Connecticut
I have seen replacement switches with pigtails you would have to crimp or solder on the packard connectors. The switch is not the same as the low air switches although they may look similar.
Will
 

phxmark

New member
35
0
0
Location
Glendale, AZ
Not sure if this is the one I am looking for:
[h=1]Dana Spicer Tire Inflation Pressure Switches 673345 NSN 5930-01-446-9234 CTIS

$(KGrHqNHJCEFH!yP)+CIBR0TvTeTvQ~~60_3.JPG[/h]
 
Last edited:

SLOrazorsedge

Member
415
3
18
Location
San Luis Obispo, Ca
How did you bypass the pressure switch? My truck is a NOS M932A2 complete 2011 rebuild with 6 hours and 13 miles on it. Everything on the truck is new. It worked fine on recovery, pulled a M146 trailer home with it 300 miles. Have used it for several months off roading and hiway use using the CTIS flawlessly. Suddenly had same issue as above, front tires deflated with five flashing lights. Read the 2012 operation TM. Drained system, fired it up and hit "run flat". System could be heard running air checks and then five flashing lights again. I ended airing up all the tires to 80psi using the outside valve stems. Fired it up, same five flashing lights and the tires aired down automatically to 53psi on all tires. Read more on TM, turned truck off including master battery switch and disconnected CTIS cable from plug on transmission tower. Let sit for a few minutes, plugged it back in. Long story short, seemed things were cycling correcting for a couple minutes and then again got five flashing lights. Any suggestions? I also just found and printed 122 pages of CTIS "Troubleshooting Procedures" from the 2012 updated TM's. I'll be going thru those diagnostics. Seems that we all are having a similar issue with the front tires airing down and getting five flashing lights.
 

Suprman

Well-known member
Supporting Vendor
6,744
170
63
Location
Stratford/Connecticut
If the system is attempting to fill but the front tires are deflating then you have a fill air leak. The system is sending fill pressure but due to a air leak the front wheel valves are only seeing around 12psi which holds the wheel valves open and makes you dump air. Probably a bad hub seal somewhere.
 

phxmark

New member
35
0
0
Location
Glendale, AZ
Make sure all the fitting at the tire fill valves are tight. Mine didn't work when I got the truck due to a defective pressure sensor on the wet tank outlet. Replaced it and it started giving me the 4 flashing lights. I reset the unit and then did a walkaround when it was running. Had air leaks at the two front fill valves. I tightened all the fittings on the front wheels and all was good. Every once in a while I get the four flashing lights, but only when it is very cold outside. My guess is that the quick release valves under the truck are sticking when it is cold. Four flashing lights seems to mean that the pressure in one or more of the tires cannot be maintained. Five flashing lights mean that there is an issue with a CTIS component. Either the control unit or a pressure sensor. I would check ALL the connections to all the sensors, control unit and solenoid valves. I had the five flashing lights once and pulling the plug and resetting the unit fixed it.
 

SLOrazorsedge

Member
415
3
18
Location
San Luis Obispo, Ca
Thanks brothers! I didn't have any issues until we had this cold snap in Cali, its been down to 11 degrees in the morning at the ranch. After my front tires completely deflated, I manually aired them up. They havn't gone flat again but the system does not air up to hiway pressures. I've got the 2012 TM dianostics and the Spicer now, so I'll start from scratch tightening up fittings and tracing electrics. I'll be back at it this weekend.... :0(
 

Suprman

Well-known member
Supporting Vendor
6,744
170
63
Location
Stratford/Connecticut
Maybe some moisture somewhere is froze up in the system creating a partial blockage which is causing less pressure to the wheel valves then. The system sends 12psi to the wheel valve to hold them open to dump air. Issues can cause pressure loss to the wheels and mimic the dump pressure.
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks