Diagnosing CTIS M1078

Lugnuts

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You have followed the plumbing, left is “T” d to right and front is “T”d to rear. There is no way to send air to just one tire. In emergency mode, the timed routine is changed and the controller simply checks the tire pressure much more frequently and adds as necessary, instead of the normal 15 minute checks. It probably also overrides or loosens the parameters on the need for stable pressure at it’s pressure checks. One leaking tire will deflate on it’s own but as soon as the system is pressurized and all the wheel valves are open, 3 good tires will attempt to fill and equalize the leaking tire...

the quick release/dump valves don’t make much noise when air is applied to their supply. The only time they really make noise is when pressure is released from the supply side and they dump their output side to the vent to equal that low supply pressure. So every time the PCU opens the control solenoid and releases system pressure, they honk briefly.

Now if your supply was feeding slow, as in the issue you described with the protection valve on the wet tank, as the system sent enough pressure thru the dump valves to open the wheel valves, the greater wheel pressure would flow back to the dump valves and be vented until the supply side of the dump built enough pressure to equal the tire pressure...

On my truck, right after that protection valve on the wet tank, there is a T fitting. The smaller line(circled in first pic) runs to the hydraulic manifold to supply air to the cab air suspension valve. The larger line runs directly to the passenger cab floor to feed CTIS and the fan control solenoid... The CTIS line is just out of sight behind it... you can just see the big line to ctis all the way to the right in the second picture...


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Thank you. When I get back to it and reseal that hub I will continue on the quest. Until a later date.
Lugnuts
 

Lugnuts

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I got back to the issue of the leak on front left hub. I procedurally disassembled the tire, drum, removed the planetarium, and pulled the hub. No big deal except one. I have not read the manual but I need to and that is in regard to pulling the rear seal. Seems as if the spindle is larger than the seal and won't come off by pulling but like I say haven't read the manual and any other type of removal doesn't seem logical.
The seals are not the quad rings I expected as in the CTIS M35 so I am asking where is a good vendor to get the seals? Fleetpride says the seal number is good and available for $55 thereabouts but no listing in the company which would mean that they probably really don't want to fool with it. Have I got any advice or vendors from the Comrades of Steel Soldiers. The seal number is Meritor A-1205-Q-2435
The seals look good but it seems perhaps trash and oil in the air line found its way to the hub and perhaps caused an irregular sealing surface. Whatever, replace while I'm there.
And if anyone has experience on that rear seal and would like to respond, please, do so and thanks
Lugnuts

After I wrote this I called Memphis Equipment (Melanie Carter) and they had 5000 of these seals at $33 a piece/ They can ship those out for $10 but ask for the lesser price FedEx in the bag shipping to get that.
 

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M1078MAN

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You know whats wierd, when I saw that picture of the P# of the seal, it was like flashback..there was a pierod of time we could not get these seals,, we had 15 or so trucks parked for a few months.

Not sure why it flashed back..anyways
 

MrMikey4026

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I bought a stack of 10 of those seals on ebay, seems they were like 167$ no freight.
That is like 16,70 each.
Front and rear wheels are the same number.
I bought CTIS and front axle shaft seals the same way, same price.
I don't want to be stranded somewhere with parts several days away.
 

Lugnuts

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Well, I changed out my seals on Left Front Hub, reinstalled, tested, found a crack in the metal line from hub to Hollow Lug Stud, brazed repaired, and tested again. System held air.
Reassembled for Test Ride. CTIS acted differently. The barking of the Quick Release Valves definitely diminished.
Now the Highway Light kept blinking as the unit worked. As I understand the blinking light means that is is working. When the air stabilizes ie tires are filled to level desired the light goes steady? That is how I understand from what Ronmar wrote earlier it is suppose to work.
About 2 miles into the ride I had 2 blinking lights on the Controller, (extreme ends from each other) One was the Highway Button and one was the Run Button.
I could not find in the manual a description for 2 flashing lights but mention was made of 2 solid lights, Any Feedback?

This is going to be one of those stupid questions (or observation) but I tend to tread where only fools go just for grins and giggles but... if I have a Wet Tank Side leak (one that kicks the Air Compressor on quite frequently but yet I hear the drier vent so I know it is coming to pressure) will it effect the stabaliztion diagnostics on the output side? I realize that if the pressure drops below the Air Pressure Sensor for the Controller that it will cause the unit to turn on and off... will this cause a code to set?
Thank you guys,
Lugnuts
 

MrMikey4026

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When I was repairing my CTIS, I had several controllers. Some of them had some very strange errors. I found a good one and it has worked flawlessly.
It might be a good idea to borrow a known working controller, so you don't end up chasing crazy controller issues.
I unplug my controller when ever I disconnect the batteries or jumpstart.
It's always a good idea to disconnect the batteries when welding on the truck.
 

Ronmar

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The manual does talk about 2 solid lights not flashing. Maybe yours is not flashing. As MR mikey mentioned the controllers can fail in weird ways. But it would be good to make sure you are delivering all the pre-requisite conditions.

You say the air dryer purges, that means the governor has met its set pressure. But at what pressure is it set? You need to connect a pressure gauge to the wet tank to confirm that It reliably goes above the 117 psi CTIS switch point. (Governor should be set to 125 PSI).

If you look at the possible causes for the 2 light fault, governor adjustment and air supply from wet tank to ctis are right up there at the top of the list. That air supply includes the protection valve. It looks like a regulator on the back side of the wet tank, but it acts like a CTIS wheel valve and only allows air greater than 85 PSI to exit the wet tank, thus retaining at least 85 PSI to feed the brake system. If it is not flowing properly that could be interfering with the process...

from your description it sounds as if it is starting out normal, single light flashing as it is working. But eventually it fails to meet some goal, like not filing fast enough, and the display changes to 2 lights... if you are not reliably exceeding/closing that117 PSI Pressure switch or have too much air leaking away instead of feeding the tires that could also be your issue.
 

tennmogger

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I have an LMTV 1078 that times out with two lights as yours does. It is a timeout at about 15 minutes if the system is not able to achieve the pressure goal. In my case the failure is because of a leaky seal in the left front axle/hub. I can hear a whistle from it sometimes. I have found that moving the wheel about half a revolution will allow the completion of the cycle. Of course I need to fix that seal. Summary, a leak anywhere that is slow enough to not immediately fault the system but bad enough that high pressure leaks out, will cause that fault. My system achieves XC exery time. Pushing the HWY switch again makes the system start over.
 
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