923a2 won't shift out of neutral

[TexAndy]

Just got a 923a2 out of hood. Stashed at a friend's place down the road from me.

Got batteries installed, but not the three smaller wires coming up from the floor. One of the ring terminals for those wires won't stay on and needs to be replaced.

Checked all the fluids, transmission fluid is just a teensy hair low.

Primed the fuel pump, then the lines and got it running. CTIS "works?" the rear flat tire airs up.


PROBLEM: Truck won't shift out of neutral. I mean, I can move the selector to R or 1-5, but I can't feel the truck doing anything. Had the transfer case in high. In my 923, I can feel it shift when I put it in reverse or 1-5. With this 923a2, nothing happens. No go when I press on the accelerator pedal in 1-5 or R, either.

About the only thing I can think of to try next is topping off the transmission oil (yes, I know, first thing I should have done). If that doesn't work, dropping the transmission oil pan and seeing what it looks like. And the oil on the end of the dipstick seemed ok to my untrained eye.

From reading a few of the problems other people have had tho, it sounds like if the oil is just too low or the filter clogged, I should at least be able to feel it shift out of neutral at a standstill, right?

 

[Suprman]

Trans fluid is checked with the engine running and in neutral. Pull the shifter up make sure the cable did not get disconnected. I believe you can see is selector input moving on the side of the trans when you are moving the shifter have someone under the truck and check. Make sure the transfer case is not out of gear and between high and low. It is hard to get in and out sometimes. I believe the smaller wires are for the ABS but dont quote me on it.

 

[TexAndy]

Transfer case selector lever feels mushy.

So I set it as high as I could get it, went under the truck and looked, then set it as low as I could get it and looked under the truck again. It seems like the lever might not be getting the transfer case out of neutral.

hard to tell without a second man to operate the lever while I look underneath the truck.


eta: Thanks suprman, I will check that as well. Xfer case issue addressed above. I think that might be my issue. On my 923a0, it has definite stops. You can feel when it's in low, neutral, or high. On this one, it just doesn't feel like it's going into or out of any particular position.

 

[Suprman]

If the xfer case lever moves up and down then there is a very good chance you are in neutral. Drain the air tanks and then try to put it in high
Will

 

[mkcoen]

Straight from the -24 Troubleshooting section:

29. NO RESPONSE TO SHIFT LEVER MOVEMENT
Step 1. Check transmission fluid level (TM 9-2320-272-10).
Drain or fill fluid as necessary (LO 9-2320-272-12).
Step 2. Check for broken or disconnected shift cable.
If broken or disconnected, notify DS maintenance.

Is Keith your DS maintenance?

 

[TexAndy]

Keith is DS maintenance for swmbo, now. Didn't look like the cable was broken or disconnected, but it sure didn't seem like the lever had the same range. I tried "pumping" the lever up and down a few times to see if I could get it to pop in or out, but I don't think it has enough positive control versus how much its stuck. Assuming thats the problem, anyways.

Thanks, Will. Do you mean with engine off, drain tanks and then try to put xfer case in high? I'll try it Monday.

 

[TexAndy]

Hm... can I safely pry on or otherwise try to directly manipulate the plunger that goes into the xfer case? Rather than manipulate it via the lever in the cab, I mean? Or do I risk damaging something?

 

[M35A2-AZ]

Is the drive shaft turning coming out of the transmission when you have it in gear?
If so I would think the transfer case is in Neutral, with the truck off and the power on, can you hear a click coming from the under side of the truck. If not your transfer case lockout in not working.
Try to drain the air from the truck, then try to push the transfer case shifter all the way down for high or up for Low.
But remember not to put it in reverse in low.
I would not pry on it.

 

[mkcoen]

Keith is DS maintenance for swmbo, now.

Had to google that one. I just call mine ma'am.

 

[TexAndy]

Is the drive shaft turning coming out of the transmission when you have it in gear?
If so I would think the transfer case is in Neutral, with the truck off and the power on, can you hear a click coming from the under side of the truck. If not your transfer case lockout in not working.
Try to drain the air from the truck, then try to push the transfer case shifter all the way down for high or up for Low.
But remember not to put it in reverse in low.
I would not pry on it.

I didn't think to check that at the time. Will look at the transmission to xfer case shaft while engine is running when I go back Monday.

 

[TexAndy]

Well, the xfer case is unstuck. Ya'lls suggestion to try it with engine off and air tanks drained seemed to do the trick for that.

However, it still won't shift into gear. Transmission shifter does nothing.

With 1-5 selected, with engine running, the short drive shaft from transmission to xfer case does not spin.


With engine off, I had someone manipulate the transmission selector. That does actuate the lever on the driver's side of the transmission.


I'm at a loss.

 

[Suprman]

Drop the pan pull the filter take a look at the fluid condition and if there is any metal shavings.

 

[Carlo]

It dose not look good. If it was mine I would drop the pan. Does the trans oil smell burnt?

 

[TexAndy]

If there are metal shavings, what do you think it could be?

Doesn't smell burnt. I haven't dropped the pan yet, tho. The oil on the end of the dipstick looked good.

 

[TexAndy]

Question:

What is the lever on the side of the transmission that is connected to the shifter cable connected to inside the transmission housing? What does it do? Is it possible for whatever it's connected to inside the housing to get stuck and yet the lever on the outside still move freely?

 

[TexAndy]

34. NO RESPONSE TO SHIFT LEVER MOVEMENT
Check if shift linkage is disconnected or broken.
a. Connect or replace linkage if necessary (para. 4-75).
b. If linkage is sound, replace transmission (para. 4-71).
END OF TESTING!

That's what the DS section of the TM says about No Response to Shift Lever Movement.

Guess I'm probably screwed.

 

[Jim Timber]

The depot level of maintenance is always to replace the parts that don't work right. It's never to fix the problem with the components. Find the TM for the transmission and you should have the proper troubleshooting steps.

I got conned into thinking I'd be fixing jet engines with my MOS 67U - nope, the crowning achievement of AIT was remove and replace the engine. Whooopdie friggen do!

 

[Jim Timber]

http://igor.chudov.com/manuals/M939...on-AT-MT-HT-Transmission-Operators-Manual.pdf


http://allisonparts.net/Allison-Transmission-Parts-Tips.html

 

[Suprman]

The cable that goes down from the throttle area controls fluid pressure. The easiest way to describe it is a kick-down cable. You can tighten or loosen it to increase or decrease trans fluid pressure for softer or harder shifts.

 

[TexAndy]

Per the troubleshooting tips Jim posted:

[SIZE=-2]2. Shift selector linkage unhooked.[/SIZE]	[SIZE=-2]2. Connect linkage - shift selector gates must agree with model. Detent positions at transmission must conform with gates on shift selector. (Refer to vehicle service manual.)[/SIZE]
[SIZE=-2]3. Shift selector linkage defective.[/SIZE]	[SIZE=-2]3. Repair or replace linkage. Shift selector linkage must be free and secure.[/SIZE]
[SIZE=-2]4. Main pressure low.[/SIZE]	[SIZE=-2]4. Refer to Chart E, Low Pressures.[/SIZE]
[SIZE=-2]5. Shift selector not engaged at selector valve.[/SIZE]	[SIZE=-2]5. Replace defective part. (Refer to applicable service manual.)[/SIZE]
[SIZE=-2]6. Transmission fluid level low.[/SIZE]	[SIZE=-2]6. Fill to proper level. (Be sure dipstick calibration is correct for specific model.)[/SIZE]

I'm thinking it might be 4 or 5. But I can't find a manual that describes how to check the main pressure. And I'm not sure where the selector valve is located.

Is the selector valve the same thing as the modulator valve?

From looking at the Allison user's manual, it sounds like the modulator valve is what you're talking about suprman, re: harder/softer shifts.

What confuses me is that it appears to be in the place where Item number 17 on page 3-399 of the -24 TM. But it doesn't look the same. What I was looking at was a lever attached to a cable that moved when the shift selector was used.