LMTV CTIS Question

[Union5]

My department just acquired a 2007 M1079A1. It's in amazing condition with very low miles. The only issue we have with the truck is with the CTIS. Most of the time all five lights are solid and it will not deflate. All the research I've done points me to the the ECU being bad or a bad wiring harness. However, every once in awhile the CTIS will come to life and work fine. The other day I started the truck, let the air tanks fill, then shut it off, plugged and unplugged the ECU a couple times and it started working. I go out today and same issue, on startup 5 solid lights. Anyone with any ideas?

 

[coachgeo]

Lot of threads in here on the topic. Unfortunately. PITA to to search in here... so try using Google Advance to search this website for various iterations of CTIS such as CTIS Flashing LMTV along with CTIS Flashing LMTV etc. etc. One of the threads in here is about how to build a manual version of the controller.

Have you gone thru any TM checks from the A0 manuals?

 

[Suprman]

There is an air pressure switch off the side of the right tank tells the system there is enough pressure to do its
thing. I would check that first and then any electrical connections.

 

[Union5]

I'll check the switch. After we run the truck we always drain the air if it's gonna be parked for a couple days. Should we not be doing that?

 

[Suprman]

No always drain the tanks. Does water come out? Do you have the finned tube air dryer?

 

[Union5]

No water comes out. No idea on the finned tube air dryer.

 

[Suprman]

To the right of the battery box. The older style dryer with fins does a lousy job, if you have the newer dryer you should be fine. Moisture in your air lines will give you alot of problems once it gets below freezing.

 

[Bobcat701]

Your department can disconnect the CTIS and pump the tires up to 50 PSI for now. The truck will then be operational, while you work out the gremlins. Since its a 1079 it will probably be on dirt or paved roads 90% of the time. I have a 1078 and I unplugged my CTIS, the fat tires allow me to traverse all terrain I have been on so far.

Once I fix a few other items on the truck I will revisit the CTIS. Its the most fun vehicle I ever owned.

Regards.

Joe

 

[Union5]

The tires basically stay at hwy mode while the lights on the selector are all solid red. Even when the ctis chooses to work the light blinks on the hwy mode for a couple seconds before staying solid red. Just working toward a fully functioning truck. We are located on the beach in NJ and the sand mode would be nice to help get over the dune getting off the beach.

 

[Suprman]

Sometimes the air pressure governor is set just a bit too low to trigger the switch. You can try turning it up just a tad. Governor is mounted on the air compressor. Could be a clogged air dryer also causing slightly low pressure.

 

[f8617]

...Even when the CTIS chooses to work the light blinks on the hwy mode for a couple seconds before staying solid red...

That's proper operation during startup...one CTIS light is flashing as truck air pressure rises, the brakes take priority, the cab rises up on the air ride bladders, the brake alarm stops wailing at ~90psi, then the CTIS checks air pressure--the CTIS light then goes solid red, and the CTIS vents/chirps a loud burst of air. Every 5-10 minutes the CTIS will recheck tire pressures automatically and vent/chirp a burst of air when its satisfied the tires are properly inflated.

 

[Union5]

Yeah and 1 out of 10 times that is exactly how it operates on startup. Then maybe 3 out of 10 times the ecu will show solid red for awhile then just solid hwy. But most of the time is 5 solid lights with the ctis system not working.

 

[f8617]

The point of failure on my CTIS was a pulled wire inside the wet-tank pressure switch connector.

Test: see pix for proper function of wet-tank pressure switch connector (master power OFF).

 

[Union5]

Was that causing 5 solid lights?

 

[Suprman]

5 solid lights is a hard fault. It can be caused by the switch. Did you turn the air governor up slightly yet?

 

[Union5]

5 solid lights is a hard fault. It can be caused by the switch. Did you turn the air governor up slightly yet?

How do I access the air governor?

 

[Suprman]

On the driver side of the engine is the air compressor. Governor is mounted on top of the compressor. Plastic cap comes off and there is a threaded rod with a flat head slot and locking nut. I forget which way increases or decreases pressure. A very slight adjustment is all you need. 1/4 turn maybe. Did you check the air dryer. If its clogged up it can cause a bit of low pressure?

 

[Union5]

Ok new wrinkle in the problem. After plugging and unplugging the ecu it started to work. Automatically Switching into sand mode. When I pressed hwy it airs the tires back up but both hwy and sand stay lit. Now if you hit the ecu it will go from sand mode or all 5 lights on at once. Since "tapping" the ecu gets it to work is that my issue? I will still try the governor. But the air cleaner is good to go

 

[Suprman]

Could be a bad ecu or wire harness. The ecu is a high failure item.

 

[Union5]

Anyone know if a ctis ecu from an A0 will fit an A1? Im thinking it should the A1 upgrades where engine trans and brakes right?