New M35A3 Questions

[Monkeyboyarmy]

Finally got a chance to get some pictures for you.The round switch on the drivers side with the 2 wires is the neutral safety switch.Just disconnect the wires and jumper the two together with a test lead or piece of wire.MAKE SURE the transmission is in neutral.

 

[Skycop]

Thanks so much! Its only here that people will get down and dirty just to help you out from a thousand plus miles away! I will be up in the yard tomorrow and will take a look and see what good I can do with the info. I will keep you posted.

 

[Skycop]

Well and update. I went out today to go look at the possibilty of the neutral switch and she started on the first try. Today it is about 50 degrees and the other day when it was cold it was about 35 degrees or so. Maybe that solenoid...unless you think of something else.

Regarding the air pressure fluctuation, it occurs when I move the steering wheel back and forth. When the truck is OFF I don't have any air leaking out when I turn the wheel back and forth (other than the exhaust air upon turing the wheel whatever way). As you can see by the attached video, it fluctuates greatly and it doesn't matter if the engine is running at 2K RPM or idle. Every time you see the gauge fluctuate I am beginning to turn the wheel to one side or the other. Sorry, I don't know how to embed the video into the post, when I tried pasting it from Youtube it didn't work.

http://www.youtube.com/watch?v=syLvUbs9Cbo

 

[milbri09]

Well as I am new to SS and this is my first post I will try to make it good. The m35a3 got a 140,000 referb thanks to all of the tax payers. With this said you get a few new toys. the engine is a 3116 CAT mechanical engine, that said parts can be had at your local CAT dealer. They will be pricey but you can still get them.

The transmission is an automatic made by Allison. Great unit. Be sure to go to Allison's website to get general infol. Most importantly is to make sure that the shift lever and the trans. linkage are "timed" correctly. The tranny is great but I have had to pull more than I care to remember due to this situation. I would drain the trans. and change the filter and oil to Allison's specs. Military standard in this unit is 15-40. Not very good for the trans.

As far as the air leak is concerned. I would go straight for the air govenor. It should be bolted to the air comp. A new unit can be had at any truck parts center. Gasket, govenor, pipe dope and bolt it up. Then you can adjust it.

Now for your CTIS issues. They are ok. They just require alot of maitenance. You can always test the axles one at at time. Then if you find that all of the alxes are holding air you can go to the control manifold. Now you have a choice. Repair automatic system, or build your own. You could put a few fittings together and plumb all the axles together giving you only one place to fill or drain your tires. Refill with glad hand adapter. Now for the automatic system. It has several parts that may not be readily available. I have not work on one in several years however with a few pics. I am sure I will be able to jog my memory. But if it only a power issue test this way. Remove four wire plug from ECU. Using a multi-meter test the wires to a good frame ground. Test wire #3 for power with key on. It powers up from the light switch. Voltage is dependent on light switch position. Wire #4 is 24v all the time, key on or off. So with that said you can test for power in these two ways. If you have power ok. If not you can make a harness to power up the display. But its easiest to find out why you don't have power.

I hope that this helps. If you need anything else. Just ask. Always happy to help.

 

[Skycop]

Thanks for the response.

First off, is the tranny an MT643 by Allison? I was aware of the rebuild and what they did, but I didn't even think to change the filter and fluids from the engine oil they use in there (go figure). Thats a good idea, but first I need to identify the tranny. What do you mean when you are talking about the tranny being "timed" correctly. Please elaborate.

Second, do you think it is an air leak since the system recovers so quickly? What exactly does the governor do (obviously governs the flow of air), but how and to what parts etc? The brakes, winch control (yes I know it is a hydraulically driven winch), and all other pneumatically operated parts work just fine (minus the CTIS) without the fluctuation.

I will tackle the CTIS issue once I get everything else knocked out (still wondering about the starter issue, as from what I have heard from other members the solenoid sticks when cold?)

Also, one other tid-bit. When I fired up the truck this morning (again, it is about 40 degrees outside and it started right up), I noticed the air pressure gauge indicated 0 for a bit and then all of a sudden jumped up to 60 psi and then climbed normally to just shy of 120. On a ogod note, it seems the system will hold a charge on the air system after then engine is off for quite some time. After 3 hours yesterday it had only decayed to about 80 psi.

 

[milbri09]

Ok as far as I remember the transmission is a 1545 Allison. What I mean about "timed" is simply the when the shift handle is placed in the drive position that the transmission is truely in drive. I have found before that the linkage will hold the trans between gears which will deff. take the trans. out.

The air govenor actually controls when the air compressor is allowed to build air. It has a few lines on it. It is rather in-expensive to replace and always the best place to start because it controls all of the air on the truck. The govenor will acutally drain the air tank because when it gets to 120 PSI it allows the compressor to just pump air and not fill the tanks. When it get down to about 80 PSI it should shart to refill the tanks. Another thing to do is to make sure that the air tanks are cleaned out as well.

Let me know if you need anything else

 

[Skycop]

Well this starter issue...grrr. We need something that is reliable lol. The deuce is starting just fine now, but since I had the issues with her cranking up I have it in the back of my mind that she won't work when I need her to. Any suggestions? Still leaning toward the solenoid unless someone can think of anything different.

 

[milbri09]

ok for your starting issue. You can take the starter off and take it to a local starter/alternator shop. They should be able to take it apart and test it for you. You could do it yourself with a few tools and a multimeter. If you find anything bad you can get those parts only. The shop if they are reasonable should only charge you a few dollars to take it apart. If everything is ok, I would start looking at the truck wiring for the problem.

 

[Stretch44875]

On the air issue, the M35a3's have an air assist steering added on. Every time you turn the wheel, the steering air cylinder will use and exhaust air to make the power steering work. It can quickly use up the air in the air tanks if you are doing a lot of steering. I believe they have a safety valve so it wont run your air tanks below 60 psi.

Dennis

 

[Skycop]

Ok, so the starter is coming off tomorrow and we are going to get it rebuilt..althought it has been starting just fine. However, as was said before this thing needs to be reliable.

This weekend we are going to tackle swapping the soft top on our A3 for the hard top on our A2 (VFD has to get the hand-me-down) as they will be using it in the summer anyway!

I guess my main beef with the air issue is that it seems to retain a charge just fine except when steering. Again, it rebounds quite nicely, for example when I went to air up the tires and continue my photos for our user's manual (by the way, I have an abbreviated UM that I created for our A2 if anyone wants it shootme a PM). I would turn the wheel back and forth, and after about 2 turns (keep in mind the same result is indicated on the gauge whether I turn the wheel 1/4 of a turn or actually steer it while moving or stationary) my "recovery" indicates about 95-100 psi although the gauge drops down to just about 60 psi during the turn.

 

[Skycop]

Well as I am new to SS and this is my first post I will try to make it good. The m35a3 got a 140,000 referb thanks to all of the tax payers. With this said you get a few new toys. the engine is a 3116 CAT mechanical engine, that said parts can be had at your local CAT dealer. They will be pricey but you can still get them.

The transmission is an automatic made by Allison. Great unit. Be sure to go to Allison's website to get general infol. Most importantly is to make sure that the shift lever and the trans. linkage are "timed" correctly. The tranny is great but I have had to pull more than I care to remember due to this situation. I would drain the trans. and change the filter and oil to Allison's specs. Military standard in this unit is 15-40. Not very good for the trans.

As far as the air leak is concerned. I would go straight for the air govenor. It should be bolted to the air comp. A new unit can be had at any truck parts center. Gasket, govenor, pipe dope and bolt it up. Then you can adjust it.

Now for your CTIS issues. They are ok. They just require alot of maitenance. You can always test the axles one at at time. Then if you find that all of the alxes are holding air you can go to the control manifold. Now you have a choice. Repair automatic system, or build your own. You could put a few fittings together and plumb all the axles together giving you only one place to fill or drain your tires. Refill with glad hand adapter. Now for the automatic system. It has several parts that may not be readily available. I have not work on one in several years however with a few pics. I am sure I will be able to jog my memory. But if it only a power issue test this way. Remove four wire plug from ECU. Using a multi-meter test the wires to a good frame ground. Test wire #3 for power with key on. It powers up from the light switch. Voltage is dependent on light switch position. Wire #4 is 24v all the time, key on or off. So with that said you can test for power in these two ways. If you have power ok. If not you can make a harness to power up the display. But its easiest to find out why you don't have power.

I hope that this helps. If you need anything else. Just ask. Always happy to help.

When you are talking about #3 and #4 wires please give me a reference. I am learning as I go. Our city mechanic is great, but i have to do the research on this stuff before I get it to him as he is swamped and needs the help. Thanks!

 

[milbri09]

CTIS wiring. If you remove the cannon plugs from the back of your CTIS computer this is what you will find.

You will be holding the cannon plug in your hand. It is the metal plug that unscrews from the CTIS box. Now looking at the end of it you will see one of two things. Either a pin or a socket, these will mate with the wiring of the CTIS. Now there should be a black colored rubber piece in the end of the cannon plug that is labeled with either numbers or letters. Uncle Sam used both. I am pretty sure they are numbered in this case because I looked through some of my stuff and that is exactly what it says to check.

You will need to check for 24V+ on the #4 pin or socket with the key on. This is for the display warmup and to power the system. The #3 pin/socket is connected to the light switch so that depending on which lights you are using you are not "too bright" at night and don't get used for target practice. The other wires in the harness are for the signal generator circuit, but they only have anything to do with the system once it is on. I will look for the resistance of the sig. gen. and post it for you. Off hand I think it's around 200 OHM.

Hope that this helps

 

[Skycop]

Rgr. Will advise once I take a look. Thanks for your help, and if I didn't say so already, your first (and subsequent posts) have been very helpful. Thanks sir!

Also, with regards to the pneumatic system and my issues with it, I don't mind fixing the governor, but do you have any other suggestions about the fluctuation issue? Upon doing some research the governor regulates how much air is in the system (max psi I think), and it seems like I lose pressure and it builds back up like it should....just has an initial "jolt" upon activation of the steering etc.

 

[milbri09]

I have some good news. I am getting the TM's for this truck, called in a favor from a friend. But it's ok cause he owes me many more. Should be able to get them and post them in the resources section when I get them. Then you will be able to look up all of the specs. for the truck. I should even be able to get the trouble shooting guides for the entire truck.

Now for that silly air system. The govenor does indeed limit max air. but it also controls when the system starts to build air, as in when the pressure gets low it "turns on" the compressor. Also note that the air dryer is part of the air control system. It's "spurt" of air is from the govenor and pushes water out of the system. You might want to check the dryer out. All of the parts are easy to get. Should be a Bendix unit. The filter portion could be clogged, or the valve could be bad and leaking. It's sorta hard to say. I think you said that it will keep 80 PSI overnight. That is not too bad, but it should actually be better than that. I would hope for 100 PSI. But that is not causing the fluctuation. The best test is to start the truck and have someone turn the wheel after it builds up to max pressure. Start form straight. Shut off the truck. Now turn all the way to one side and hold. You should hear a small amount of air come out of the steering assist cyl. exhaust port. and while still turning the wheel it should eventually stop. This means that the cylinder has reached max travel and is not leaking internally. There is also a valve that regulates the amount of air to the system should only be around 30-40 PSI, so it's possible that it is allowing too much to the steering and that is the cause too. But who lnows the guage could be bad too. Maybe we should tee one into a line just to be safe.

Personally I would start with a new filter and valve for the air dryer.

Now you have some more things to test. I hope it's not too much to swallow up front. Once we get yourair system right, we will get that CTIS working. And you will love it. I promise.

 

[Skycop]

As far as 80 psi overnight...I am dreaming! It will hold 80 psi for about 3-4 hours. When I shut the truck down I don't hear any leaks, however. I will work on the dryer and governor, which are things that I probably should go ahead and do anyway. I assume places like NAPA would have the parts, or would I need to go to a specialty place for big trucks? Thanks again.

 

[milbri09]

Ok I made a little mistake. The drier is not a Bendix, it's a Haldex,

The rebuild kit is a DQ6036 ARTIC, includes filters, seals and instructions on rebuilding

Or the DQ6026 standard kit.

Neither include the heater.
They run about $125.00

 

[Skycop]

Ok, so I don't think it is the Air Dryer system as the valve (both quick release and slow release) work just fine with no leaks with the engine running or shut off. I apologize for my accent, but I attempted to narrate the videos.

[media]http://www.youtube.com/watch?v=9DSQ_umnEOI[/media]

 

[Skycop]

Part II. Sorry for the quality but I am recording on the Blackberry.

[media]http://www.youtube.com/watch?v=_ZtHmPCuh_c[/media]

 

[Skycop]

Final Video

[media]http://www.youtube.com/watch?v=wc-N45d9Ybg[/media]

 

[Skycop]

By the way, with the cold snap here in Texas, I finally experienced the sticky starter solenoid due to the frigid temps. We will be replacing that, but when the solenoid was sticking it would at least make a clicking noise when the starter was activated. When I was having the issues previously it wasn't even doing that. Weird.