M923A2 CTIS Problem

[doghead]

Have you serviced your air dryer ever?

 

[SLOrazorsedge]

Thanks Suprman, it sure seemed to coincide with the cold snap. I'll be getting back out to again this weekend running these issues down.

 

[RicheyOne]

Just wondering......I have attempted to pressure up my tires on a 91 m923a2 and I have tried the highway mode and hear the valves in the cab click on; however did not pressure up the 2 slack tires. Now, there is a sticker on my shifter column stating "CTIS is neutralized" Do all GL vehicles have this and does this mean it is disconnected?

 

[Suprman]

The unit that owned it probably put schrader valves in the wheel stems. Chances are it had some failure they close not to fix and just disabled it.

 

[Tommy Frantz]

I have an M925A2 with five lights flashing on the ctis. I air up the truck, shut everything off including the battery master, and then start everything back up. Before the lights start flashing again, I hit one of the other ctis buttons and one of the valves on the back goes, 'paaahrrump!' and then all the lights go back to flashing. Anybody else have a similar problem? I've been looking in the Dana/Spicer instructions, but they don't describe that sequence of events….

 

[Suprman]

Sounds like you have an air leak somewhere. When the system does its initial pressure check it detects a leak and faults.

 

[RustyM923]

I have an M925A2 with five lights flashing on the ctis. I air up the truck, shut everything off including the battery master, and then start everything back up. Before the lights start flashing again, I hit one of the other ctis buttons and one of the valves on the back goes, 'paaahrrump!' and then all the lights go back to flashing. Anybody else have a similar problem? I've been looking in the Dana/Spicer instructions, but they don't describe that sequence of events….

It's been my experience (<---this means I'm not an expert by any means) that 5 lights flashing means the system either cannot check pressure, or cannot achieve pressure.
A: Can't check pressure often means there's a schrader valve where it shouldn't be.
B: Can't get to pressure often means there's a leak somewhere.

Since yours is going to 5 flashing very quickly, I'd vote that it can't check pressure. Check to see if there's valve core in the t-piece that bolts to the wheel (short side).

When mine gives 5 flashers, it's usually after a compression valve slips off on the wheel. It'll try for a while, then give up with the 5 flashing lights. I snug it back on and all is right in the system.

 

[Tommy Frantz]

How can I keep the thing pressurized long enough to find leaks? I have a feeling its a leak problem, because the system worked when I first got the truck. I have to admit that I have run over a few trees with the truck, but afterwards I checked carefully underneath and can't find anything pulled loose.

 

[RustyM923]

How can I keep the thing pressurized long enough to find leaks? I have a feeling its a leak problem, because the system worked when I first got the truck. I have to admit that I have run over a few trees with the truck, but afterwards I checked carefully underneath and can't find anything pulled loose.

I would suspect that you don't have a leak. If you have a leak, the system tries to fill until it figures out it can't reach pressure. What you have is more likely "not being able to check pressure". The most common cause of this is that a valve core has been added between the CTIS valve's hose and the rim valve assembly. That's what I'd check first.

Honk Honk...I love that sound every 15 minutes as I drive. It's like having a clock...sort of.

 

[SLOrazorsedge]

Welcome to the 5 flashing CTIS light syndrome brother...symptoms to my truck are exactly like yours. The truck CTIS worked perfectly for 4 months following purchase until the cold weather hit us, 11F central coast Pozo area. I've found a few minor leaks, replaced all the air tank drain valves (leaking). I recently bought a new pressure switch and wheel valve filters that I haven't installed yet. I'm not going to give up on the CTIS, I loved it when it worked.

 

[Tommy Frantz]

I like the ctis, too and don't want to disable it. I looked at the wheels and there are schrader valves in the line between the ctis valve and the tire. There is another on the other side of the tire port. Looks like they're placed just for convenience sake,, you can manually add air from either side of the tire. Some folks have said the schrader valves affect the ctis, but I don't see how. All of my trucks are like this,, I have three of them so I have a good statistical sample.

Question---where are the wheel valve filters?

Another question---tire balance question---why do just the front wheels have the big weight opposite the ctis valve? This weight looks like it weighs a lot more than the ctis valve. Also, is it possible to balance these tires? I just got a 923a2 from gl that was overhauled at RRAD, and the tires in the back are so far out of balance that they shoe your teeth out when they sync up right. I was thinking of rigging up an old hub with ball bearings to do some static balancing...

 

[RustyM923]

This is where they add a core to disable the CTIS. The whip of the CTIS valve threads over it and it appears to be connected properly.
However, when your brain says "check pressure", you'll get an instant 5 flashing lights.

 

[Tommy Frantz]

Thanks, Rusty!! I'll look there for a schrader valve!

 

[SLOrazorsedge]

Check out the diagram/pic on page #60 of the Dana trouble shooting guide for location and installation of the wheel valve filters:

http://dana.com/wps/wcm/connect/25f...=url&CACHEID=25f359804b1f69fba8acfff859534476

My wheel valve stems look exactly like that. I'll have to get back out to the truck for inspection. My question will be if there are schrader valves on the inside stem, why did the CTIS work okay for 4 months and then suddenly malfunction?

 

[Tommy Frantz]

My wheel valve stems look exactly like that. I'll have to get back out to the truck for inspection. My question will be if there are schrader valves on the inside stem, why did the CTIS work okay for 4 months and then suddenly malfunction?[/QUOTE]

My question exactly. My ctis worked until about a month ago. I thought it had to do with me running over trees and having something pulled loose.

 

[cumminsbandit]

My CTIS worked good when i got my truck and a week latter it stopped working. I must have inflated and deflated the system 5-10 times in the first cople of days and it worked great, now?.... it always had 1 tire that lost air over night even when it worked. how can the system detect such a small leak?

 

[phxmark]

@Cumminsbandit, what are the symptoms? Four or five flashing lights? Four lights indicate that the system cannot maintain pressure and five flashing lights indicate a problem with a CTIS electrical component. If you have four flashing lights, check all the air connections at the tire valves, seals, dump valves and sensors. If you have five flashing lights, check all electrical connections at the senors and valves. I get five every once in a while when driving and I have it traced to the connector at the control unit. I get four lights when it is real cold out. I just run the system in run flat mode until everything gets warmed up and moving again when I get four flashing lights.

 

[MtnSnow]

Cumminsbandit & Tommy,

See the PDF I posted at http://www.steelsoldiers.com/showthread.php?119010-CTIS-problems&p=1491174&viewfull=1#post1491174 as it will help you narrow down your problem(s)

 

[RustyM923]

My CTIS worked good when i got my truck and a week latter it stopped working. I must have inflated and deflated the system 5-10 times in the first cople of days and it worked great, now?.... it always had 1 tire that lost air over night even when it worked. how can the system detect such a small leak?

The system is not that smart. It just checks when you first start the truck and then again every 15 minutes.

The leak is probably just a leak. Either a wheel o-ring, a nail in the tire (could happen), or a leak in the CTIS valve assembly somewhere. break out the soapy water and find it.

It's easier to fix these systems when you're only chasing one problem...

 

[mkcoen]

Top light flashes on mine while it's building pressure then once the tanks are almost full all lights start flashing. I tried the "disconnect/reconnect" fix and that didn't work so I guess it's now down to checking each component. The truck has less than 500 miles on it since original issue so my guess is something is clogged for sitting 23 year or an o-ring has rotted someplace. At least the tires stay inflated all the time.