M1078 fmtv ctis

Ohiobenz

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Well, back OT... while my new fan clutch hose is being made.
I removed the PCU from the truck to find it dusty but no sign of oil etc. Removing the cover revealed a pristine unit.

20180806_120130.jpg

Proceeded to test the solenoids but was a little confused at the markings in the plug not matching the schematic.

20180806_121655.jpg

The schematic has no pin C

Screenshot_20180806-130427_Drive.jpg

So using a meter, needle and a jumper wire, I penetrated the insulation on each wire to verify which was which.
This is what I found....

20180806_131939.jpg

The D', F', E' being the unmarked wire from the solenoid.
Now, that doesn't match the schematic either, which shows the ground connecting A and B, while the inside of the connector clearly shows F/A as the common pin.

It appears for sure that the control solenoid is OK, even though per the schematic the D' wire should be on pin A.
There seems to be a short inside the potted plug in order for Supply and Deflate both to be on the same pins.

So none of this makes sense. Do I have the wrong schematic? How do wires in a potted plug even short to each other??
 

Coffey1

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All you need to do is check coils for continuity take coils or body off and check holes the coils open and close for trash and I mean really really small trash
 

Ohiobenz

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Replaced the PCU with one from a working CTIS - from NV555.
Also installed the new Purest air dryer.
CTIS flashes all 5 until wet tank switch closes, then goes to solid HWY. Pressing SAND the mode light comes on but nothing happens, same as before the PCU swap.
 

Ohiobenz

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Well..... wiggle the CTIS harness and the lights start flashing on the controller... time for a new harness methinks...
 

dbeasty

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My LMTV A1 CTIS controller is flashing as well...

After studying the threads and the Spicer CTIS Troubelshooting Guide AXTS-0015 I disconnected the pressure switch round electrical harness and shorted the A-B connectors, result was no change in the behavior after turn on/off.

After that I went to measure T-L contacts on the ECU harness connector and expected them to be well shorted, since that is where I thought the A-B from pressure switch leads, but they were not..no beep.

Is there some other connector between the ECU harness and the pressure switch connector?

Am I doing a correct thing in shorting the A-B to elimnitate bad pressure switch/low pressure in the system?

I will go with the toner and try to trace the wires and try to fugure out if there is direct wire from the pressure sensor switch to the CTIS ECU round harness.
 

Ohiobenz

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Ctis

Screenshot_20180810-155327_Drive.jpgIf you connect the 2 terminals at the tank you are in effect sending a closed switch signal.

Screenshot_20180806-130427_Drive.jpg

This the section of the CTIS harness to the PCU.
The electrical TM would be helpful in running a pin to pin continuity check of the harness.
 

dbeasty

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After watching some videos, my CTIS lights are not blinking, they are flasshing really fast, almost solid.

I did some testing and I was not able to trace/tune the connection from the pressure switch the CTIS harnes, seems like the wire is not going to harness, which does not make sense to me. I will do one more continuty test tomorrow.
 
Last edited:

dbeasty

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Weather got better, so I could return to the CTIS troubleshooting.

The air pressure was good in the system and the CTIS, however , the CTIS system was acting erratic.., mostly solid blinking, but sometimes went to solid HWY mode.

I had a new NOS CTIS controller, so I did put that in and CTIS started to work; "well" almost.

It deflates OK to XC/Sand, inflates, but the when I try to inflate it to HWY mode the rears on one side get only to 55PSI and the other 45 PSI, the fronts are close to each other around 64PSI.

I suspect I have some kind of leak/plug in the rear part of the CTIS system.

Essentially what its doing its solid HWY for a bit and than goes HWY flashing for a bit..and back to solid and back to flashing HWY and so on..

I have manually inflated rear tires to 64 and they are holding fine and the HWY light stayed solid.

Per CTIS manual I am supposed to do following:
Check the following for leaks: Tires and rims
Tire hose
Wheel valves Repair faulty components and recheck the system.

Note that I have also recently installed newer model of air-dryer, so not sure if there is a water in the system...

Any suggestions on troubleshooting?

Does the engine needs to be running for the CTIS, to inflate, since might be easier if its quiet to try to find leaks etc.. and soapy water and try to see bubbles??

I do have on spare CTIS wheel valve on spare, so I could probably swap those on the side where there is an issue..
 

Ronmar

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You need engine running and wet tank full to activate the pressure switch on the wet tank so CTIS can start its thing. A CTIS inflate command will drain the wet tank down to the 85 PSI protection valve close point in 3-4 seconds... those tires take some volume...

For quiet, you can connect shop air set at 120 PSI to the emergency gladhand at the front. Be sure to be on level ground and wheels chocked as connecting air there applies park air/releases the parking brakes...

Different inflation on the rear tires and both lower than the front sounds like you might have a bad CTIS axle seal. Give it an inflate command and look for air exiting out of the axle vent line(connected to a open port up on the frame) air exiting there = bad axle seal...
 

weldergq692000

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Ok, My CTIS is working again. Here is a rundown of what I did. First and foremost I had to identify the pressure
switch that everyone was talking about. Mine is right above the CTIS supply line on the wet tank.
View attachment 585146

I then separated it and marked it with red dots for aligning it so I could connect it and disconnect it really fast several times after applying cleaner and then the Dielectric grease.
View attachment 585149 View attachment 585150 View attachment 585151

I then did the same on the connectors at the CTIS controller and the connectors at the manifold. Here are also photos of the products that I used.
View attachment 585153View attachment 585154View attachment 585155 View attachment 585158
Do you have a part number for the pressure sensor? I'm trying to find it in all the forums.
 

In2Fords

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I just purchased my M-1078 a couple of weeks ago, and the control box on the dash was missing. After reading several posts on how the system wasn't the most reliable, I decided to go the manual route with a regulator and some gate valves. For me it works fine, and I can set my tires at any pressure. If you would like more info let me know.
Yes, the truck I'm waiting on for the euc to clear is missing the ecu, I've decided to go manual anyway for the Same reasons as you, I've screen shot one post on how to do it, just haven't worked it out yet since I don't have the truck yet.
 

Reworked LMTV

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Ok, My CTIS is working again. Here is a rundown of what I did. First and foremost I had to identify the pressure
switch that everyone was talking about. Mine is right above the CTIS supply line on the wet tank.
View attachment 585146

I then separated it and marked it with red dots for aligning it so I could connect it and disconnect it really fast several times after applying cleaner and then the Dielectric grease.
View attachment 585149 View attachment 585150 View attachment 585151

I then did the same on the connectors at the CTIS controller and the connectors at the manifold. Here are also photos of the products that I used.
View attachment 585153View attachment 585154View attachment 585155 View attachment 585158
Having a hard time getting that pressure sensor out of the manifold. Did you do anything special?
 

ogdobber

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Los Angeles
I’m on my phone... there might be a better place to post this but I’m pretty excited because it works!
High and low pressure ctis
Saw a video of a guy that changed out the pressure sensor to a 150lb and was able to get 80psi on highway mode, but everything else was raised ~30psi as well. I didn’t want this because I don’t want to sacrifice my rig in sand. So I put a two way manifold and mounted both sensors toggling the vdd and the signal on a 6 way switch.
Works great, I have 80psi for highway on high mode and everything works normal on low.



Sent from my iPhone using Tapatalk Pro
 

coachgeo

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North of Cincy OH
I’m on my phone... there might be a better place to post this but I’m pretty excited because it works!
High and low pressure ctis
Saw a video of a guy that changed out the pressure sensor to a 150lb and was able to get 80psi on highway mode, but everything else was raised ~30psi as well. I didn’t want this because I don’t want to sacrifice my rig in sand. So I put a two way manifold and mounted both sensors toggling the vdd and the signal on a 6 way switch.
Works great, I have 80psi for highway on high mode and everything works normal on low.



Sent from my iPhone using Tapatalk Pro
When you get chance.. it is to more folks benefit to go back and upload your pics to here. you can use the url that tapatalk use to put them here. aka... tapatalk does NOT upload pics to a site.... they host the pic on their server and do a link in your post. every company that host pics iin last twenty years has failed eventually and good informative threads/post turn into crap because all the pics go away as the host fails.
 
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