Problem with cab air ride ?

[1951M1078]

Air bags will not inflate. Just started ? Where in the TM's is the best place to start ? Have CTIS unplugged. All red lights and flickering ? Going to go manual for the CTIS. But have not started that yet.

 

[1951M1078]

Also,does anyone have a quick explanation on how it is controlled ?
Have 100+ psi in the system.

 

[Dock Rocker]

Have you pushed the knob in and turned it right that controls the air ride?


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[1951M1078]

Yes,Sir.
When I got the truck did a full system check,even unloaded the spair and reloaded it,LOL. Man the tire is heavy.

 

[olly hondro]

Don't know if my truck is typical: the cab air bags do not inflate until AFTER the air tanks are charged.

I have some work to do on mine as the cab bounces like the truck has a flat tire. Pinned it for now (and control knob turned CCW).

 

[Suprman]

Right side of the air tanks is a pressure protection valve that feeds the cab air level system. The air hyd functions are fed from a different air source. Check make sure the ppv is opening.

 

[coachgeo]

Once I get to that portion of the project...... am thinking just canning the air ride and using cab shocks as the Steyr 12M18 does. Same cab, less hassle, less to go wrong

https://www.qtponline.com/products/shock-absorber-cab-suspension-43201.html


oem steyr 12m18


EXCAP's mod they sell for expedition trucks.

dual shock as you can tell and an extra brace is on the OEM setup too. It holds a mud flap/rear section of front fender. This dual setup becomes more important if your adding a cage, or roof rack w/ tire etc. etc.

BUTTTTTTTTTTT should note here.... many with Steyr 12m18 campers upgrade to air ride suspension seats cause from what I've read the ride is sorta harsh... sooooo..... though it sounds like a less complex set up if one were to swap to their spring assisted cab shocks in our FMTV's ... that does not mean it is an upgrade. Might be a downgrade actually ending up with a pretty ruff ride... that means you now need an expensive air ride seat. What to do what to do...... lol



side note..... Steyr made a bunch of very similar cabs including doka's for the commercial and fire service trucks. Some withOUT the portion behind the seats at all. Wall is behind seats. Would be a great way to make an expedition habitat longer.

 

[Ronmar]

Yep, The protection valve only lets air pass when the wet tank is above around 85PSI. There are two lines coming off of the protection valve, a large one and a small one. The large one feeds CTIS and the small one feeds the cab air suspension. You could start by loosening the small line fitting and see if any air leaks out. The line goes from that fitting at the outlet of the protection valve to the control valve on hydraulic control panel. From there it is up to the ride height control valve, then it splits to the two lift cylinders.

if you dont have air at the protection valve, are you sure the wet tank is getting up to pressure? If the compressor isnt getting the pressure high enough you get no air past the protection valve. What do the front and rear air pressure gauges read? You should be getting 120 PSI, and that air comes from the wet tank. If you have 120 but nothing out of the protection valve that is probably your issue. Air pressure or protection valve issues could be why your CTIS has issues...

 

[1951M1078]

Thanks,Ronmar !

I let all the air out of the air tanks and then let them refill. But It seamed the rear most tank (wet tank ? ) didn't have the pressure the others had ?
Will need to look at that ?

I will reset the air pressure. Looked lower than 120 ?

 

[Ronmar]

Well all the air from the primary and secondary tanks comes thru the wet tank so it is at least reaching the pressure registering on the pri/sec air gauges. The wet tank is smaller than the other two so will bleed off faster than the others...

If you are doing any adjustments you really need to unscrew the wet tank drain port and screw in a pressure gauge. You can then confirm accurately at what point the compressor governor is cutting off the air supply. You can then loosen a port on the other side of the protection valve and let air escape untill it stops and confirm what pressure the protection valve is leaving in the wet tank.

 

[olly hondro]

Just so y'all know: I am enjoying immensely learning what all these hoses and wires do. Following the circuits, putting on little labels, getting smarter. So, yeah, I appreciate the knowledge sharing.

 

[Dock Rocker]

Just so y'all know: I am enjoying immensely learning what all these hoses and wires do. Following the circuits, putting on little labels, getting smarter. So, yeah, I appreciate the knowledge sharing.

I am glad I am not the only nerd in the bunch.


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[Ohiobenz]

Make sure that the valve linkage is set like this. Mine wasn't and all it took was setting it correctly to get the Cab Leveling to work.
The best TM for this is TM-9-2320-366-20-3.
Also consider joining the LMTV Facebook page... pics and videos on there are very helpful!

 

[1951M1078]

Reset the air to 123 psi.

Found this leaking. Rubber looks ok but ? Old ?

Sealed it back up with gray RTV and will test Sunday.

 

[1951M1078]

Looks like the air leak was nothing. Will now start doing the other testing.

Also found on brake canisters on the rear parking brake is leaking when not set to park with the motor off. Driver side. Think I will change both champers L & R.
But need to get the air ride cab fixed first.

 

[Ohiobenz]

Search for TM 9-2320-366-20-3 on Google.
Great step by step troubleshooting.

Also my post on the LMTV Facebook page:

https://www.facebook.com/groups/1607576859556624/permalink/2115823215398650/

 

[ckouba]

View attachment 752717

Make sure that the valve linkage is set like this. Mine wasn't and all it took was setting it correctly to get the Cab Leveling to work.
The best TM for this is TM-9-2320-366-20-3.
Also consider joining the LMTV Facebook page... pics and videos on there are very helpful!

That is what the valve arm looks like before the cab airs up or after? My valve arm is level when aired up.