A2 CTIS TMs

[silverstate55]

A2 CTIS TMs (TM 9-2320-272-34P) Question

While troubleshooting my CTIS system on my M931A2 and trying to find part numbers for possible replacement parts, I noticed that the -34P in the TM section of this forum is dated 1988 and only covers M939/M939A1 trucks...while doing a search of the Interwebs, this is the newest version of the TM 9-2320-272-34P that I can find; other sources that list a newer version to include CTIS parts are all listed as "Backordered."

Does anyone have, or have a source for, a newer -34P that covers CTIS parts? Or am I missing something? I searched so long that I wore my eyes out, it's very possible that I'm overlooking something. The -24Ps only cover a single CTIS electrical harness & nothing else.

Thanks in advance!

 

[Suprman]

What do you need to troubleshoot? What are your symptoms?

 

[silverstate55]

In short I have rebuilt/serviced every CTIS part except for the 3 Safety Relief Valves that mount between each pair of tires side-to-side...I had the CTIS working briefly after cleaning up the pressure transducer, then the left front tire started going flat. I quickly aired it back up manually, shut the truck down, and heard air escaping from the front Safety Relief Valve mounted under the radiator.

At first I was hoping that this valve was able to be disassembled for cleaning, but after removing it I saw that it was sealed. Mine had a ton of rust from moisture sitting in it for quite some time, and the rust was holding the rubber flap valve open inside the sealed housing (it is pressed & crimped together, no way for me to get it apart without destroying it) which allowed the air to escape from the tire. Just in case, I pulled the axle vent, but no pressure escaped there, so the new hub seals I had installed on that axle end seem to be holding so far.

I was trying to look up part numbers & NSNs for these valves to try to find a replacement, but a search on eBay found what I was looking for...I used those numbers to try to search elsewhere for a comparable item, but the only other one I could find was available in Europe for 170 Euros plus shipping (OUCH).

But I was dumbfounded to see that I didn't have the proper -34P nor can I find a copy anywhere. Just curious what I'm missing!

Thanks!

 

[Andyrv6av8r]

In short I have rebuilt/serviced every CTIS part except for the 3 Safety Relief Valves that mount between each pair of tires side-to-side...I had the CTIS working briefly after cleaning up the pressure transducer, then the left front tire started going flat. I quickly aired it back up manually, shut the truck down, and heard air escaping from the front Safety Relief Valve mounted under the radiator.]

The dump valve that you are referring to controls both front tires; it is common to both front tires. If only your left front is going flat, you have an issue with a wheel valve on that tire or a leaking o ring/turret valve. It's not the dump valve. It will dump pressure from the lines as the truck is shut down.

 

[silverstate55]

The dump valve that you are referring to controls both front tires; it is common to both front tires. If only your left front is going flat, you have an issue with a wheel valve on that tire or a leaking o ring/turret valve. It's not the dump valve. It will dump pressure from the lines as the truck is shut down.

That's what I thought too, but I could hear air coming from this dump valve, and when I removed it I saw rust flakes & corrosion inside that were allowing air to escape (preventing proper operation). After removal, the tire stays inflated, and I had just cleaned/serviced the wheel turret as well as replaced all O-rings on that wheel a few days before. The two in the rear work fine, I'll replace the front valve when the replacement comes in & try again.

I knew I was in for a challenge when I rebuilt my air dryer...the truck was rebuilt to as-new in 2005, but when I won it at auction in 2014 it had less than 800 miles on odometer. It sat for a LOOOOONG time with moisture in CTIS lines/components. Everything I've taken apart to rebuild or service has had tons of corrosion inside. This valve seems to be another victim of it.