CTIS Troubles

[Crazymacks]

Question , my CTIS turns on and begins activating when air on secondary gauge goes to 120. It starts its checks and begins to fill tires with highway light blinking. At some point during the fill cycle usually well before tire at where they should be, it will stop, and the exhaust valve on the PCU will open, all lights start flashing, and it dumps all the air in all the tires. Even if I unplug the ECU or the PCU it continues to dump everything out and I cannot seem to stop it ??
OR after it starts cycling and airing up tires with highway light blinking, if I turn truck off, once again, the exhaust valve on the PCU opens and will empty out flattening all tires !!
Please need some suggestions LMK Thanks !! Happy New Year !!

 

[Andyrv6av8r]

I'd start with taking the solenoids apart in the PCU, cleaning and verify that all are working and not sticking. . Ohm your coils too. If all is good, start checking wheel valves.

 

[KN6KXR]

Well I have some similar issues I'm working through and am making some progress. Here's the advice I have to start:
-Get a shop air supply rigged up. You'll never be able to hear what's going on with the motor running. My shop I have plumbed at 80psi so I cut in another regulator I run at 125psi and then string lines over and feed through the front left service glad hand. Works great.
-Download the P2P program and study the animation sequence. Sounds to me like your not making the leak check and maybe the exhaust valve is sticky on the pnuematic control? That would leave the QRV's open. Maybe I dunno I'm new at this. Study the animation program it's really cool. In the TM section here someplace. Follow the install instructions exactly.
-Get TM 9-2320-272-24-2 the CTIS maintenance section is really good. Has all the tests. Each wheel, the QRV's, the hub leak checks, rebuild and check the pneumatic controller, etc... As suggested above start with the pnuematic controller. I just did this it's not hard. If you have an old pressure transducer there are some updated ones on eBay get one.
-Get TM 9-2320-272-24P-2 this will have all the parts and exploded diagrams.

Not sure if you have an A0, A1 or A2. I have an M936A2 that never got the wheel valve update. So I got them on eBay and am essentially in the deep end on this. Working my way through this methodically one wheel and thing at a time. So far I've found a couple wheel valve leaks and maybe a hub seal leak on the rear. This would cause the flattening I'm experiencing like you. I'm hoping I can "shock" the rear hub seals back in to place like a read on another thread here without taking the hub aparts we shall see.

CTIS is super cool! Also it's a PITA and very prone to failure. I think you have to be a dedicated MV collector if your going to stick with it. They age and the seals go bad. This isn't bad except it flattent the tires when it fails. I'll be adding field tools and parts so I can bypass the system if I have to. Spare schraeder valves, tank valves, tools. If you unplug the fill line from the QRV you can stick a schraeder in there real quick and isolate the tire/system. Don't forget a good 20-ton jack to hold it up while you do this and care for the tire but you should have one of those anyways.....

Hope that was helpful and good luck (to the both of us)!