Instruction manual for using the CTIS


New member
Merritt Island, FL
Does anyone have a manual for how to use the CTIS?
I read English, but I swear the display is greek to me!!

I figured out the On and Off switches (aren't you proud), and I figured the other 4 configured switches for various terrains, but I don't understand why "flat?" keeps showing up or what to do to just increase set points, or decrease them, or anything else??



Well-known member
Perry, Ga.
Here's a start. You should download ALL the M35A3 tech manuals off the website. The way you find specific info on CTIS on any tech manual is to open the manual, type in "CTRL F" and the search or find menu will come up, type "CTIS" in the window for search of all CTIS related items, and you will find a great deal more on operation and maintenance of CTIS components.

From tech manual TM9-2320-386-10
The CTIS allows the operator to manually select a tire pressure suitable to the
terrain being traversed. The system incorporates an Electronic Control Unit (ECU)
and air regulating system which provides and maintains the correct air pressure to
all tires at the same time. The ECU controls the manifold, which automatically
directs compressed air to inflate the tires, or signals the deflation port to deflate the
tires according to the operator-selected terrain setting. The ECU monitors and regulates
air system pressure in 30-minute intervals and compensates for thermal tire
pressure changes as recommended by the tire manufacturer.​
TM 9-2320-386-10
1-14.2 Change 1​
The CTIS is activated and deactivated with an ON/OFF button on the ECU. In
the event the unit is not deactivated prior to engine shutdown, it will automatically
activate when the engine is started again.
Terrain switches on the ECU are pressed by the operator for the terrain conditions,
which are identified as emergency, sand/mud/snow, cross-country, and highway.
Once the terrain switch has been pressed for desired pressure setting, the air
system inflates and maintains all tires to the appropriate tire pressure corresponding
to a recommended vehicle speed. Provided operator does not experience overspeed
conditions, no additional operator inputs are required once presets have been
The air regulating system consists of a controller overspeed signal generator,
power manifold, and wheel valves. If the operator exceeds the recommended vehicle
speed in either emergency, sand/mud/snow, or cross-country modes, an overspeed
warning will activate, (flashing max speed display) alerting the operator of the overspeed
condition and to signal operator to either decrease vehicle speed or select a
higher tire pressure on the ECU. In the event the operator fails to slow down or
select a higher tire pressure in approximately one minute, the system will automatically
increase air pressure to the tires to the next higher tire pressure setting.
In the event of one or more small air leaks anywhere in the system, such as from a
tire puncture or leak at a connecting line, pressure can be maintained by pressing a
terrain switch on the control panel. When doing so the initial test pressure sequence
begins. If the air feeder lines cannot hold at least 6 psi (41 kPa) the controller display
will read FLAT in the upper right corner, indicating to the vehicle operator that a
large air leak, such as a damaged/disconnected air line or a flat tire, exists. When
FLAT is indicated, the vehicle operator may elect to call for assistance, or try to drive
to a repair center using the vehicle’s run flat mode.
Should a particular tire or connecting line experience catastrophic failure or a
leak which exceeds the capacity of the compressor, the CTIS may be turned off,
allowing the wheel valves to keep each tire individually isolated. Additionally, the
damaged portion will remain isolated, as a safety measure, until it is repaired. A
priority pressure switch in the manifold monitors the pressure in the air reservoirs
and isolates the CTIS if this pressure drops below 75 psi (517 kPa). Minimum
requirement for the operation of priority systems (brakes, power steering assist,
horn) is less than 75 psi (517 kPa), so safe operation is assured. If the CTIS suffers complete
failure, the operator accesses a manual wheel valve at each wheel and inflates
each tire from an external air source. If tire pressure falls below 10 psi (69 kPa), CTIS
will not inflate tire. The CTIS should be deactivated during operation in extreme cold,
0° to -65°F (-18° to -54°C). Extremely cold temperatures can cause air seals located at​
each wheel to fail.


New member
Troubleshooting CTIS is in the TM 9-2320-386-24-1-1

TM numbers for your truck should be listed on the dash plates.


New member
Twin Cities, MN
The CTIS is a great system when it's working, but you need to fully understand it. Please check out the manuals, they can be a little confusing, so print the CTIS pages and sit in the truck when you play with it to understand it.

From the PMCS table:

• Check CTIS with engine operating at 1300 RPM.
• If CTIS is inoperative, the unit may be turned off and tires manually inflated or deflated to desired pressure. If pressure other than highway setting is selected, operator must observe speed/pressure limitations displayed in the cab.

a. Turn ECU switch (1) on and check display on ECU (2). Ensure tires deflate and inflate to the correct tire pressure for the terrain condition selected.

Note: If tire pressure falls below 10 psi (69 kPa), CTIS will not inflate tires.

b. If correct tire pressure cannot be attained, deactivate CTIS by switching ECU (2) to OFF position. Manually inflate/deflate tires (para. 3-9).

Note: CTIS ECU unit must be switched OFF to manually inflate tires.

Gauge tires for correct air pressure using ECU and tire inflation gauge and hose assembly. Manually inflate as necessary. For normal operation of vehicle, tire pressure should be as follows:


Highway 43-47 psi (296-324 kPa)
Cross-Country 31-35 psi (214-241 kPa)
Sand/Mud/Snow 18-22 psi (124-152 kPa)
Emergency 11-15 psi (76-103 kPa)


New member
Merritt Island, FL

My Deuce is set up with Super Singles, versus the standard dual rear tires. They are Michelin tires and according to the side wall, they can handle more pressure than 47 psi when running..
does the CTIS account for the super single tires or just for duals?
It had been working very well, but then this weekend when I set it for mud sand snow, it took them down to 12 psi rather than 20... It reinflated them to 32 for xcountry, but I wasn't sure what was up with that?

I have read the section of the TMs about the CTIS and have sat in the truck and reviewed the settings. Any tricks to keeping it dialed in right? Also, someone said I can attach a QD valve on the truck off of the compressor to manually inflate the tires, etc.... Where do I run it from? Has anyone else done it?

Thanks again!!


New member
Merritt Island, FL
Here's another question....

What kind of line do I need to get if I need to re-do one of the air lines and where should I buy it? I haven't worked on air lines before....

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