Lmtv CTIS

[IDVET]

Hey guys, I have searched through threads to find any pictures or diagrams to help but I’m drawing nothing. I found threads about converting from the CTIS to a manual valve and regulator set up but I’ve got some questions. In the -20 it has a diagram of ports on the CTIS manifold, 3 is pressure from the trucks wet tank into the manifold, 4 is output from manifold to the tire system, but then there’s 25... it says manifold vent, is this where the manifold Vents off excess air when airing down? Thanks in advance for any help.

 

[MrMikey4026]

Yes, attached to the plastic valve cover.
In your picture #2

 

[IDVET]

Yes, attached to the plastic valve cover.
In your picture #2

unless I’m reading the TM illustration wrong the pics labeled 3 and 4 are input and output, it’s the one labeled 25 that I’m questioning.

 

[Ronmar]

25 is the vent line. The S port is supply, the other port is the one that runs down to the dump valves and wheels.

The PCU has 3 solenoids. One is the control solenoid and is normally open and must close to seal the system before anything else can happen. When the controller is done it releases/opens the control solenoid and it vents system air quickly into that plastic case and thru that line outside the cab.

The supply solenoid is normally closed and when opened admits truck air to the PCU manifold/system. If the control valve has closed, this air pressurizes the system all the way to the wheels. More than 6PSI in the system opens the wheel valves, connecting them to the manifold where pressure is measured. Keeping the supply solenoid open fills the tires with truck air.

The last solenoid is the deflate solenoid and is normally closed, and when opened connects the PCU manifold to that little brass 6.5PSI check valve on the front of the PCU near the supply and system hoses. When this valve opens the system vents air down to that 6.5 PSI. 6.5PSI on the truck side is enough air to keep the wheel valves open, but way less than is in the tires so air flows out of the tires.

The dump valves for each axle are remote pressure regulators. Whatever pressure is felt on the input, they match on the output either by passing input air to the output, or venting the output side down to match the input.

so when you close control, and give a shot of supply, the wheel valves open at 6.5PSI and the tires are connected to the system which stabelizes at a tire pressure. When you add more supply the dump vlaves see the increase on the truck side and pass it to the tire side and the tires inflate. When you activate the deflate solenoid, the manifold and truck side of the system drops to 6.5PSI, the dump valves see this and vent the output side(tire side) down to 6.5 PSI. Since this is enough to keep the wheel valves open, airflows out thru the wheel valves and is exhausted by the dump alves.

when the control valve is opened the truck side drops to 0 PSI, the dump valves match this on their output and since it is not enough to keep the wheel valves open, they close… so it is normal when opening control to get a brief woosh out of the dump valves untill the wheel valves close…

 

[IDVET]

25 is the vent line. The S port is supply, the other port is the one that runs down to the dump valves and wheels.

The PCU has 3 solenoids. One is the control solenoid and is normally open and must close to seal the system before anything else can happen. When the controller is done it releases/opens the control solenoid and it vents system air quickly into that plastic case and thru that line outside the cab.

The supply solenoid is normally closed and when opened admits truck air to the PCU manifold/system. If the control valve has closed, this air pressurizes the system all the way to the wheels. More than 6PSI in the system opens the wheel valves, connecting them to the manifold where pressure is measured. Keeping the supply solenoid open fills the tires with truck air.

The last solenoid is the deflate solenoid and is normally closed, and when opened connects the PCU manifold to that little brass 6.5PSI check valve on the front of the PCU near the supply and system hoses. When this valve opens the system vents air down to that 6.5 PSI. 6.5PSI on the truck side is enough air to keep the wheel valves open, but way less than is in the tires so air flows out of the tires.

The dump valves for each axle are remote pressure regulators. Whatever pressure is felt on the input, they match on the output either by passing input air to the output, or venting the output side down to match the input.

so when you close control, and give a shot of supply, the wheel valves open at 6.5PSI and the tires are connected to the system which stabelizes at a tire pressure. When you add more supply the dump vlaves see the increase on the truck side and pass it to the tire side and the tires inflate. When you activate the deflate solenoid, the manifold and truck side of the system drops to 6.5PSI, the dump valves see this and vent the output side(tire side) down to 6.5 PSI. Since this is enough to keep the wheel valves open, airflows out thru the wheel valves and is exhausted by the dump alves.

when the control valve is opened the truck side drops to 0 PSI, the dump valves match this on their output and since it is not enough to keep the wheel valves open, they close… so it is normal when opening control to get a brief woosh out of the dump valves untill the wheel valves close…

Thanks for the in depth explanation, I appreciate it!