CTIS help

[Frederic]

I need some CTIS help! My CTIS controller decided to up and die. Got a new one, black, programmed for higher tire pressures from Walt Grigsby Trucks out of Bend, OR. System keeps high pressure at HWY mode, about 76 lbs and fills up just fine. Here is the issue: When put into XC or Sand mode, it deflates out of the exhaust valve just fine, but doesn't stop deflating, and will release ALL air in tires, which is a problem. PCU under the front passenger dash had a slight crack in it, sealed it with JB Weld and also put gasket sealer all around the rubber seal. The transducer is the stock transducer. Previously, I put in a 150 lb transducer with the old green CTIS controller and had no issues with anything until the controller went to all 5 lights solid. I can't hear any air leaking and I have sprayed everything with soapy water that I can find with no results. Any help or suggestions would be much appreciated. Thanks. Frederic

 

[Ronmar]

In order for the dump valves to stop dumping, either the truck side(between PCU and dump valves) air pressure needs to go up to tire pressure, or to drop below the pressure needed to close the wheel valves.

Now when a deflate cycle is finished, it gives a shot of air to stop deflate and check pressure, but when it is done completely, the control
Solenoid is released and it should vent cleanly and dump and wheel valves should close

It sounds as if you may have a restriction in the PCU vent line or the control solenoid/PCU is having issues. People have had mud dawbers build nests in the vent port behind the grill that have caused this. It restricts flow enough so the system cannot vent the truck side below wheel valve close pressure(6PSI) faster than the wheels can supply the air to keep the pressure above wheel close pressure…

 

[Third From Texas]

Also, is it the right controller for the truck variant? Because A0 controllers don't work in an A1R, etc, etc, etc

 

[Frederic]

In order for the dump valves to stop dumping, either the truck side(between PCU and dump valves) air pressure needs to go up to tire pressure, or to drop below the pressure needed to close the wheel valves.

Now when a deflate cycle is finished, it gives a shot of air to stop deflate and check pressure, but when it is done completely, the control
Solenoid is released and it should vent cleanly and dump and wheel valves should close

It sounds as if you may have a restriction in the PCU vent line or the control solenoid/PCU is having issues. People have had mud dawbers build nests in the vent port behind the grill that have caused this. It restricts flow enough so the system cannot vent the truck side below wheel valve close pressure(6PSI) faster than the wheels can supply the air to keep the pressure above wheel close pressure…

Thanks so much for the ideas. I’ve been out of town, but I’ll check on your suggestions this week and keep you posted. I appreciate your help.

 

[Frederic]

Also, is it the right controller for the truck variant? Because A0 controllers don't work in an A1R, etc, etc, etc

Well heck! How do I figure out which variant? Built in 1997 apparently. Came with a green controller and purchased a brand new black controller. Thanks for your help.

 

[wheelspinner]

Well hell! How do I figure out which variant? Built in 1997 apparently. Came with a green controller and purchased a brand new black controller. Thanks for your help.

A0 can use any of them. A1r can only use the new one

 

[TomTime]

Well hell! How do I figure out which variant? Built in 1997 apparently. Came with a green controller and purchased a brand new black controller. Thanks for your help.

Never mind, wheelspinner got to it before me.

Good luck.

 

[Frederic]

Thanks so much for the ideas. I’ve been out of town, but I’ll check on your suggestions this week and keep you posted. I appreciate your help.

Hello again Ronmar. I checked all dump valves for the mud dawbers. Nothing. I don't even think we have those here in WY. The brass relief valve coming off of the PCU seems to empty and then close just fine. Which air line is the vent line coming off of the PCU? Is there a solenoid inside of the PCU or somewhere outside? The square black and brass actuator, not sure what it is called, that is above and to the right of the PCU, which has two wires going into it was rather hot when I touched it. Is that related? Thanks.

 

[Ronmar]

The thing with the wires is the fan control solenoid. They are on all the time, unless the fan is on, so getting warm is normal.

There are 3 solenoid valves in the PCU(under that bottom cover). The PCU vents into the plastic cover on the bottom. There is a hose attached to that bottom cover that runs down to a port on the floor. That is the one you don’t want to get clogged, if the tires are dumping, clogged dump valves are not your problem.

The ONLY time air should come out of that brass relief valve on the PCU is when the system commands a deflate. It is 6.5 PSI and is used to regulate the manifold pressure down to just above the wheel valve closing pressure. With the truck side lower than the tires, the dump valves shifts and vents tire air to deflate the tires.

Re-reading your symptoms, this may be a PCU problem. The deflate valve in the PCU may not be closing completely When the controller tries to halt the deflate. Here is something you can try to help decide where the problem lies. Start a deflate cycle, then shut off the truck or unplug the CTIS controller.

If the tires continue to deflate after disconnecting the controller or turning off the main switch, the PCU is most likely at fault. If the deflate halts, something in the controller may be keeping the deflate solenoid engaged…

 

[Guyfang]

The NSN will tell you if its A0 or A1.

 

[Frederic]

The thing with the wires is the fan control solenoid. They are on all the time, unless the fan is on, so getting warm is normal.

There are 3 solenoid valves in the PCU(under that bottom cover). The PCU vents into the plastic cover on the bottom. There is a hose attached to that bottom cover that runs down to a port on the floor. That is the one you don’t want to get clogged, if the tires are dumping, clogged dump valves are not your problem.

The ONLY time air should come out of that brass relief valve on the PCU is when the system commands a deflate. It is 6.5 PSI and is used to regulate the manifold pressure down to just above the wheel valve closing pressure. With the truck side lower than the tires, the dump valves shifts and vents tire air to deflate the tires.

Re-reading your symptoms, this may be a PCU problem. The deflate valve in the PCU may not be closing completely When the controller tries to halt the deflate. Here is something you can try to help decide where the problem lies. Start a deflate cycle, then shut off the truck or unplug the CTIS controller.

If the tires continue to deflate after disconnecting the controller or turning off the main switch, the PCU is most likely at fault. If the deflate halts, something in the controller may be keeping the deflate solenoid engaged…

Well, I started the vehicle, made sure that tires were aired up under HWY, 78 lbs. Initiated the deflate cycle in XC, brass relief valve released momentarily, let deflate for approximately 10 seconds or so, turned off vehicle. Deflate ceased. Did the same thing with disconnecting the CTIS controller, deflate ceased. However, I did notice something related to the brass relief valve. After it did it's initial release, air kept coming out of the valve slowly. I could hear it, feel it, and I could push the end of the relief valve inward toward the PCU and make the air stop. After letting off of the valve end, it would "burp" a little and continue hissing. Could this be the issue? I did not hold the valve in during the entire deflate cycle. Am I able to remove that valve and check/clean/replace if necessary without damaging the PCU? I let the deflate cycle continue the approximate 2 minutes time, tires got to about 35 lbs, dump valve closed off for a couple seconds, relief valve released loudly again, and all tires started to deflate again. ???

 

[Frederic]

The NSN will tell you if its A0 or A1.

I checked data plate on the lower right of the dash and the NSN is 2320-01-354-3385. Am I looking in the correct spot?

 

[Ronmar]

Well, I started the vehicle, made sure that tires were aired up under HWY, 78 lbs. Initiated the deflate cycle in XC, brass relief valve released momentarily, let deflate for approximately 10 seconds or so, turned off vehicle. Deflate ceased. Did the same thing with disconnecting the CTIS controller, deflate ceased. However, I did notice something related to the brass relief valve. After it did it's initial release, air kept coming out of the valve slowly. I could hear it, feel it, and I could push the end of the relief valve inward toward the PCU and make the air stop. After letting off of the valve end, it would "burp" a little and continue hissing. Could this be the issue? I did not hold the valve in during the entire deflate cycle. Am I able to remove that valve and check/clean/replace if necessary without damaging the PCU? I let the deflate cycle continue the approximate 2 minutes time, tires got to about 35 lbs, dump valve closed off for a couple seconds, relief valve released loudly again, and all tires started to deflate again. ???

That relief Just screws into the PCU, but It sounds like it is working correctly. That is how it holds the truck side at 6-8PSI to keep the tires deflating. If you hold it in, the dump valves will feed tire pressure back to the truck side, without that relief venting it, the truck side will eventually equal tire pressure and the dump valves will stop dumping(takes about 30 seconds).

The dump valves are remote pressure regulators. The PCU feeds their input, and the tires are on their output port, and they have a dump port. They will try and match the pressure on their output, with that applied to their input. They either pass greater input to output, or if the output is greater than the input, they pass output back to input and if the difference is too great, it dumps air from the output side to the dump port.

The wheel valves are controlled by the air pressure on the axle side of the valve. If that pressure is above 6 PSI the valves are open, and air can flow either way thru the valve as long as the axle side stays above 6psi.

So with the control valve sealing the system and pcu and tire system at tire pressure, you open the deflate solenoid which connects the manifold to that relief. It vents everything above 6.5psi from the manifold. The dump valves seeing this on their input, mimic it on their output by dumping air on the wheel side. The wheel valves seeing 6.5 psi on the axle side and tire pressure on the tire side allows air to flow back to and out the dump ports.
At the end of your comment, you said it stopped deflating around 35 PSI, the PCU vented then shortly after it started to dump the tires again. When it does that it sounds like the controller stopped the deflate, but it kept dumping. That is when you want to shutdown or disconnect the controller connector and see if it stops…

 

[Frederic]

That relief Just screws into the PCU, but It sounds like it is working correctly. That is how it holds the truck side at 6-8PSI to keep the tires deflating. If you hold it in, the dump valves will feed tire pressure back to the truck side, without that relief venting it, the truck side will eventually equal tire pressure and the dump valves will stop dumping(takes about 30 seconds).

The dump valves are remote pressure regulators. The PCU feeds their input, and the tires are on their output port, and they have a dump port. They will try and match the pressure on their output, with that applied to their input. They either pass greater input to output, or if the output is greater than the input, they pass output back to input and if the difference is too great, it dumps air from the output side to the dump port.

The wheel valves are controlled by the air pressure on the axle side of the valve. If that pressure is above 6 PSI the valves are open, and air can flow either way thru the valve as long as the axle side stays above 6psi.

So with the control valve sealing the system and pcu and tire system at tire pressure, you open the deflate solenoid which connects the manifold to that relief. It vents everything above 6.5psi from the manifold. The dump valves seeing this on their input, mimic it on their output by dumping air on the wheel side. The wheel valves seeing 6.5 psi on the axle side and tire pressure on the tire side allows air to flow back to and out the dump ports.
At the end of your comment, you said it stopped deflating around 35 PSI, the PCU vented then shortly after it started to dump the tires again. When it does that it sounds like the controller stopped the deflate, but it kept dumping. That is when you want to shutdown or disconnect the controller connector and see if it stops…

So I shutdown the vehicle after it started dumping again after the first deflate and it stopped. I disconnected the controller after and had the same result. So, seems like the controller is doing what it should, but the PCU is not as it starts deflating again/opening a dump valve again. Fix? New PCU? Where the heck can I source either parts or a PCU other than Fleabay, I am not rich.....

 

[Ronmar]

If it stopped dumping when you disconnected the controller or shutdown, that actually sounds like a controller issue, not a PCU. Shutting down/disconnecting should remove all input from controller to PCU. Without input the PCU should stop whatever it is doing and vent any pressure, which closes the wheel valves…

 

[coachgeo]

If it stopped dumping when you disconnected the controller ...

and others have reported the possibility that disconnecting controller with power on it...... tends to stress these units and maybe even brick them.

 

[Frederic]

If it stopped dumping when you disconnected the controller or shutdown, that actually sounds like a controller issue, not a PCU. Shutting down/disconnecting should remove all input from controller to PCU. Without input the PCU should stop whatever it is doing and vent any pressure, which closes the wheel valves…

I talked with Grigsby Truck Company and was able to get a phone number/contact info for Dana/Spicer. I have contacted and will hopefully talk with them as well. According to Walt at Grigsby, they tested the controller that I bought from them on a working PCU and it worked fine. Perhaps it is a solenoid inside the PCU? Do you have any contacts/sources for a PCU if needed? Thanks for all your help. It has been invaluable.

 

[Ronmar]

and others have reported the possibility that disconnecting controller with power on it...... tends to stress these units and maybe even brick them.

Since it does not have a shutdown sequence and it is secured by simply disconnecting the source power, I would find that highly unlikely. An unplug or shutoff from the main switch, does the exact same thing…

 

[Ronmar]

I talked with Grigsby Truck Company and was able to get a phone number/contact info for Dana/Spicer. I have contacted and will hopefully talk with them as well. According to Walt at Grigsby, they tested the controller that I bought from them on a working PCU and it worked fine. Perhaps it is a solenoid inside the PCU? Do you have any contacts/sources for a PCU if needed? Thanks for all your help. It has been invaluable.

I believe superman has seals and valve cores for the main body, but they are pilot operated valves, so there are seals on the solenoids themselves and I don't know if he has those or not.. he may have a whole PCU, but you will need to contact him…

 

[Frederic]

I believe superman has seals and valve cores for the main body, but they are pilot operated valves, so there are seals on the solenoids themselves and I don't know if he has those or not.. he may have a whole PCU, but you will need to contact him…

Ok. I will see where this goes. Once again, thanks for the assistance.