Which of the TMs is for the CTIS system??

[Hoxman]

Anyone know which of the TMs goes over the CTIS... I have a leak (shocker) and need to see about the system..

Thanks!!
-Hox

 

[wb9btz]

There is not a separate TM for the CTIS. TM9-2320-386-10 gives a basic description of the system and (very) basic troubleshooting. TM9-2320-386-24-1 provides major component replacement instructions and TM9-2320-386-24P has parts lists. If your tires are going flat on their own its likely a valve stem seal leak and not a CTIS issue. If your CTIS is always showing FLAT and the tires are all properly inflated, you likely have a leak in the air lines going to the axles or seal leak in one of the axle hubs. Try running the CTIS and having someone listen for an air leak at one of the axles. Also, leaking hub seals will usually have a large oily spot at the axle vent. The info is in all of the "386" TMs... its just spread out between all of them.

 

[Hoxman]

Hello,
Thanks for the info.
We have checked the valve stem and valve stem seal. We replaced the valve stem core as well. We took the tire off and submerged it and no leaks. We put 80 psi in it overnight off the truck and no leaks.. When we put it back on the truck and pressurized the system, we could not spot any leaks with leak detector fluid. we traced all around the CTIS valve at the tire, the entire wheel, the air lines up to the splitter coming off the front axle, and we found nothing...
We disassembled the hub (tons of fun) and put in a new o-ring and now we still have a leak.... Any ides out there???

Thanks!

 

[wb9btz]

Maybe I don't understand the basic problem...

Is one or more tires slowly going flat on you -even with the CTIS turned off?

Or...

Are the tires holding air and the CTIS is not inflating/deflating them to the proper pressure for the mode selected?

Or...

Does your CTIS show FLAT all of the time?

It helps if we know exactly what the symptoms are.

 

[Hoxman]

To clarify:

Truck was turned off. CTIS system turned off.
1 week later, the left front tire was flat.

Inflated tire with my compressor.
It deflated again overnight.

As such, we re-inflated tire with my compressor, turned on truck, took rpms up to 2000. Turned on CTIS.. No innapropriate readings...
Once truck was turned off, overnight the tire deflated again.

We checked (and replaced valve stem core)...
We checked for leaks all over outside of hub, including valve stem, bead around rim, CTIS valve, lug nuts, etc. AND checked air lines all the way back to the splitter on front axle.

We re-inflated tire and overnight it went flat again....

We took tire off of truck and dunked it at his tire shop with 80 psi in it... found no leaks...
left it overnight off the truck and it held 80 psi...

Put it back on the truck and hooked up CTIS components without turning truck or CTIS on and overnight it went flat again....

We took tire back off and disassembled hub... replaced o-ring, cleaned and packed everything again... Put the tire back on the truck fully inflated and never turned truck or CTIS back on and it went flat overnight.....

What do you think?

 

[wb9btz]

Sounds like you have a bad check valve. That is the round 3 port device under the "hubcap". In normal operation you can fill the tire from either the CTIS or from the valve stem. HOWEVER, the CTIS can also deflate the tire. It does this (as I understand it) by sending short pulses of high pressure air through the check valve, then pausing for some period of time. The high pressure pulse opens the check valve and the pause allows tire pressure to decrease by venting tire air to the atmosphere. The air vents from the CTIS device located under the center of the truck... not from anywhere near the tire.

If you have a check valve that does not fully close, you have a leak -whether the CTIS is on or not.

If I remember right, there is a non-CTIS fitting on the spare tire. Try disconnecting the hose that goes to your check valve and screwing the fitting from your spare tire onto the tire that is leaking down. If the tire no longer leaks down then you have verified a leaky check valve.

I think there is someone here or on the bay that has new check valves or check valve rebuild kits.

Good Luck!