Where is the CTIS function troubleshooting section in the TM's?

[ckouba]

Had my manual CTIS system working perfectly until a roadtrip last week. After some work using the air compressor to blow air into the PCU, it appears the wiring and switch work I did are all working fine and it's sending and receiving the correct electrical signals to open and close the solenoids. This leads me to think the QRV's are not playing fair, so I'd like to troubleshoot them.

Unfortunately, I can't find the proper section for that. Can anyone point me to the correct chapter and verse? All the info I've found so far ends with sending the unit to motorpool for repair.

If anyone has a recommended procedure for troubleshooting the QRV's which isn't documented in the TM's, I'm all ears.

As always, thanks in advance.

 

[GeneralDisorder]

So what symptoms are you having when you try to run an inflate or deflate?

 

[Keith Knight]

Following this one

 

[ckouba]

So what symptoms are you having when you try to run an inflate or deflate?

The short version is the solenoids click but air fails to flow. Upon shutting it down and unpowering the control solenoid, there is no release of air. It has air to the input side but I am feeling like something in the quick release valve may now not be correctly functioning.

When I disconnect the supply line to the PCU, plenty of air is available. When I work the switches, I hear the solenoids clicking and air gets distributed differently when I apply compressor air with a blow gun, so I think the PCU is functioning correctly. All of this leads me to think it's something with the QRV side of the system.

 

[Ronmar]

The short version is the solenoids click but air fails to flow. Upon shutting it down and unpowering the control solenoid, there is no release of air. It has air to the input side but I am feeling like something in the quick release valve may now not be correctly functioning.

When I disconnect the supply line to the PCU, plenty of air is available. When I work the switches, I hear the solenoids clicking and air gets distributed differently when I apply compressor air with a blow gun, so I think the PCU is functioning correctly. All of this leads me to think it's something with the QRV side of the system.

With supply air connected to PCU, disconnect the line coming out of the PCU what runs down to the dump valves. What comes out of that outlet port on the PCU when you close control and open the supply solenoid(wet tank must be above 85PSI).

That output port feeds the dump valves for each axle in parallel, so they would all need to be bad for nothing to happen. This leads me to believe the PCU is the issue. It uses pilot actuated valves, so the small solenoid valves move a little air to move/slide an internal valve core which controls a larger air port.

While you have the output line disconnected from the PCU, you can send air down that line thru the dump valves to inflate/deflate the tires to whatever pressure you apply to that line above ~5-6PSI. This will test the dumps.

 

[ckouba]

That output port feeds the dump valves for each axle in parallel, so they would all need to be bad for nothing to happen. This leads me to believe the PCU is the issue. It uses pilot actuated valves, so the small solenoid valves move a little air to move/slide an internal valve core which controls a larger air port.

Well that makes sense. I was occupied with other items today but that is where I will start tomorrow. Stay tuned... and thanks Ron!

 

[ckouba]

I think I found the issue....

Photo taken after while trying to reassemble. The hose was out of the compression fitting. I think it's too short so it's getting replaced with a slightly longer one with fresh fittings. When I bought the truck, this line was off the fitting but I didn't realize how short it was. Replacement will be slightly over-sized to make sure this doesn't happen again.

 

[ckouba]

All good in the 'hood now. Line has been replaced with one a little longer so I shouldn't have this issue again.

Thanks to Ron for his patience and assistance.