AW4 Truth Table

[5-90]

For everyone who asked before, I finally found my ATSG AW4 manual...

1st Gear SOL1ON SOL2OFF
2nd Gear SOL1ON SOL2ON
3rd Gear SOL1OFF SOL2ON
4th Gear SOL1OFF SOL2OFF

TCC LOCK 2d gear in 1-2
3d gear in 3
3d & 4th gear in D
TCC LOCK SOL3 ON
TCC UNLOCK SOL4 OFF

Solenoid locations per ATSG
SOL1 in recess on long side of valve body
SOL2 At far end of vavle body, isolated
SOL3 Next to SOL1

NSS Truth Table
(view of connector)
LATCH SIDE
E F G H
D C B A

Shifter Connected
PARK B&C
REVERSE A&E
NEUTRAL B&C
DRIVE ALL OPEN
THIRD A&G
FIRST/SECOND A&H

Hydraulic Pressure Testing
(pressure test port on P/S of case, above NSS. It's some oddball metric thread I've not identified yet...)
Range D at idle 53-61psia
Range D at WOT 161-196psia
Range R at idle 73-87psa
Range R at WOT 223-273psia

Symptomology:
High pressures in D & R, check:
Line Pressure Cable
Throttle Valve, Downshift Plug, or Throttle Cam
Primarly Regulator Valve Sticking

Low pressures in D & R, check above AND:
Front Pump Gears and Housing
Overdrive Clutch

Low pressure in D only, check:
Forward Clutch
Fluid Leakage in "D" Range Circuit

Low pressure in R only, check:
Shift Linkage/Manual Valve Adjustment
Fluid Leakage in "R" range circuit
Direct Clutch
First/Reverse Brake


Stall Speed Test:
With engine running and parking AND service brake engaged:
Shift into D range, rev engine, and note peak RPM on tach - should be 2100-2400.
Shift into R range, rev engine, and note peak RPM on tach - should be 2100-2400.
Stall converter NOT MORE THAN 4-5 seconds, and allow fluid to cool beween tests.

Symptomology:
Low Stall Speeds in D & R:
Low Engine Performance
Stator Clutch Slipping if stall speed less than 1500RPM

High Stall Speed in D:
Low Line Pressure
Forward Clutch Slipping
One-Way clutch #2 slipping

High Stall Speed in R:
Low Line Pressure
Direct Clutch Slipping
First/Reverse Brake Slipping
Overdrive one-way clutch slipping

High Stall Speeds in D & R:
Low Fluid Level
Low Line Pressure
Overdrive One-Way Clutch slipping

Probably more than you asked for, but I thought I'd go ahead while I was at it...

5-90

 

[cykaaro]

Thanks. I don't know most of what this stuff means, but think it'll come in handy trying to learn about my AW4.
Seems my valve body has to be replaced, as my low gear is gone atm. Is it just one part? or are there one for each gearing? I know, newb question, but never been inside a transmission thus far at all. Also, what does a valve body look like?

TIA

 

[5-90]

The valve body is the big milled aluminum whatsit that you see when you pull the pan. It contains all the hydraulic valving that controls the transmission shifting and such, and doesn't usually actually "go bad" unless something else blows up.

However, it is sometimes necessary to pull it down, dismantle it, and clean it. It's not difficult to do, but you'll need new gaskets, a set of new "strainers" (little filters in the valve body,) lots of solvent, and a Polaroid camera to take pictures - to make sure everything goes back in the right place. I'm on my way out the door, but I can give you some pointers if you want later (and I've got a couple spare valve bodies around somewhere...)

5-90

 

[Storydude]

99% of this manual refers to the AW4. Troubleshooting and tear-down are spot on.
http://www.cygnusx1.net/supra/library/TSRM/at/AT_001.html

 

[cykaaro]

The valve body is the big milled aluminum whatsit that you see when you pull the pan. It contains all the hydraulic valving that controls the transmission shifting and such, and doesn't usually actually "go bad" unless something else blows up.

However, it is sometimes necessary to pull it down, dismantle it, and clean it. It's not difficult to do, but you'll need new gaskets, a set of new "strainers" (little filters in the valve body,) lots of solvent, and a Polaroid camera to take pictures - to make sure everything goes back in the right place. I'm on my way out the door, but I can give you some pointers if you want later (and I've got a couple spare valve bodies around somewhere...)

5-90

Thanks for the explaination. It really helps.
Basically I've lost my low gear. WHen I put it in, it automatically shifts back up into 2nd, which works fine, as well as drive works fine. I have lost my power switch as well [it's a '90 pioneer] supposedly because of the same problem.The dealership took a look and told me they believe it's the valve body that's the problem. It's had a new filter put in last September, [Didn't drive it across to here until december] and drained and put in new fluid. Prior to taking it in, the fuild looks like it was just put in.
I unfortunately don't have the tools/equipment or know how to do it myself, but want to learn and understand just what is going on and what they're talking about, and of course I do wonder if that is what the problem actually ise.

 

[cykaaro]

99% of this manual refers to the AW4. Troubleshooting and tear-down are spot on.
http://www.cygnusx1.net/supra/library/TSRM/at/AT_001.html

Thanks! WIll go take a look

 

[5-90]

The main thing that I've seen go wrong with valve bodies on any slushbox is that they get all crapped up with varnish and/or sludge, and need to be torn down and get a detailed cleaning. This requires getting a new gasket(s,) check balls, strainers, and any other internals.

The valve body, in our case, is in two halves with a separator plate in between. You remove the bolts you can see to dismount the valve body, and the two halves are assembled using the bolts you'll find on the other side when you get it down. You can get a tranmsission overhaul kit (basic) for $80-100 with a little looking, and that will include all the basic seals, pan gasket, valve body gaskets, strainers, and check balls - which will allow you to service the VB. Note that the kits are "universal" and there are several AW4 applications, so match up the valve body gaskets once you see what you're working with. There are usually several that you'll end up not using.

When you pull the valve body assembly bolts, you'll lift the upper half off BY THE SEPARATOR PLATE, flip it on its back, then you can lift the separator plate. STOP RIGHT THERE and take nice, clear, detailed Polaroids of both halves so you can make sure everything goes back into place - I think there are about nine check balls and three strainers. I don't care HOW good the pictures in the manual are - take your own. I can't stress this enough!

The new check balls are usually rubber-coated - they will work. In the case that a check ball seat is worn, the rubber balls will seal better than the steel ones (I keep the steel ones around for spares anyhow.)

I usually end up using old toothbrushes and either acetone or MEK to clean the valve body passages - they're small, and that's how they get crapped up. ATF is highly detergent, but neglecting changes is what causes the buildup most times.

Once the valve body is CLEAN, dry it and blow it out to make sure there's no lint leftover from the rags, towels, or whatever you use to dry it. I don't care if the packet sez "lint free," blow it out anyhow. Compressed air or canned air both work equally well.

Refer to your Polaroids for reassembly. Place the strainers and check balls and the lower gasket on the lower half, put the check balls, strainers, upper half gasket and separator plate on the upper half. Flip the upper half back onto the lower and assemble. Reinstall valve body, filter/strainer, pan, and refill.

Allow the engine to idle for at least five full minutes, then shift into all gear ranges manually for a minimum of 30 seconds in EACH and EVERY range to refill the valve body - KEEP THE BRAKE ON.

After that, you should be able to return to service.

If you are a little too worried about this, I've got a couple extra AW4 valve bodies I can be encouraged to rebuild for parts + a nominal fee, since I've done this a few times with various transmissions (THM350, THM400, THM700R4, AW4, C4, C6, A727, A904, and a few Allisons) and I'm not too leery of this - but you should make sure that it really is a valve body problem first.

You'll have to make sure that the springs for the various actuators go back in (I seem to recall that there are two) and that the solenoids get moved over - and then drain and ship your old valve body back to me.

If you're anywhere near San Jose (I didn't check,) you are welcome to come over, and I'll show you how to do the job - it really isn't that difficult.

Meanwhile, take advantage of all the service literature you can find (the ATSG manual can usually be found at the strokers egroup - groups.yahoo.com/group/strokers - in the files section. It's a .pdf file, and worth having.)

5-90

 

[cykaaro]

ROAD TRIP!!! LOL
I live north of the border, so would be a nice long trek.

WOW, this is a great write up for me. THANKS!
Couldn't tell you the whole history of the jeep, but seems some things have been done, others haven't. When I had the transmission filter done, it still had the original factory gasket seal on. They had a hell of a time getting it off LOL. Oil changes were done as far as I know, and had the front brakes redone. Just did the back drum brakes a couple months ago. Funny thing is I found out the hard way, I actually have '91 drum brakes.

I will try to get a hold of that manual and read it over so I know what I'm doing. Thanks for the offer for help with the vavle body. Will talk to my uncle. He has a friend that works on his own XJ, but not sure how much he does himself. He may be able to give me a hand, and would rather do myself, than pay the dealership. Just sucks being limited with tools etc.

Was thinking, is it worth pulling one off of one at the wreckers at all to see how it all goes together, as well as having an extra one at all? No one ever touches the transmissions I find..

 

[5-90]

That's how I learned the AW4 internals - I'd torn two apart before I got a manual.

This wasn't as bad as it sounds - I'd been thru more than a few slushboxes before, so I was familiar with how they went together. I just needed to know more of the particulars on this one.

I went and got all the AW4 pages from that "cygnus1" link, and I'll compile them into a .pdf when I get a chance and probably archie the thing somewhere for our reference. I haven't read it yet, so I can't really compare it to DC/XJ/FSM or ATSG Service Guide (I have several of the former, and downloaded a scan of the latter) but it looks pretty good on the quick read.

Still, make sure to take a Polaroid of the valve body!

I'm always willing to help where I can - so feel free to ask. If I don't know the answer offhand, I can usually look it up.

If it's any consolation, the only AW4 I HAD to tear apart (due to some sort of failure) was in my 1987XJ, where three of the four bellhousing bolts had gone somewhere else (they weren't there anymore...) and the fourth left about a half-inch of daylight between the engine and the bellhousing. The connexion therefore sagged, and the geartrain got cocked inside the case and I ended up cutting the case apart with my Sawzall to get everything out! (This explains the first spare valve body.)

When I inspected the parts, the planetary sets were wrecked, but the clutches were all in excellent shape - after about 240Kmiles and a LOT of abuse and towing (including two stints of pulling a Ditch Witch - about 13,000# - and the trailer - about 4,000# - back and forth to the shop. Didn't break 35mph, but it got it there and back again!)

All in all, I've gotten quite fond of the AW4 - it's a damn good box as far as automatics go. I was nearly shocked to find it was a Toyota design, until I found it was put behind the Turbo I6 in the Supra...

5-90

 

[cykaaro]

I can totally understand that. I've never been that great at the book learning type. Give me hands on and getting my hands dirty, and I can learn so much more and faster. Did a search through google and grabbed the ATSG manual. Will read through it tonight at work me thinks. I"ve actually printed out the '88 FSM, not that I understand much of it, but haven't come across a '90 at all, although they're probably really similar I would suspect.f

I guess I now understand going to the supra page for the trans. Good idea for making into a pdf file. Time is always an issue though with things like that.

I'm the same way, and really appreciate you taking the time for me on this. It will be nice when at some point I can do most of everything myself. That's something I'm working towards. Learning on mine as well will allow me to do more on the '89 Laredo we're getting. That one the GF wants to restore to stock.Should be a good project for me none the less. All the toys get to go into mine is all!

Damn! I wonder how the bolts fell out. With my limited funds, I'd be freaking!! but sounds like a really good learning experience from it though. My biggest concern is always rust causing things to break. Looking into getting a rust proofing undercoating as it's in need of it. Some is ok though, as when I was leaking quite a bit of oil, it's coasted things pretty good for some of it.

It's amazing what these things can haul if you push them. My bro who I got mine form, hauled a huge a$$ uhaul trailer from northern Ontario all the way to Seattle, no problems. Only thing is the springs are sagging 2" below stock now. [Hopefully getting that fixed next week. Don't like hitting my bump stops] What I wonder some time is with it sitting for three years, what did that do to things.

All in all it's run like a champ. Only major things I've had to do since getting it back is a new gas tank, since mine was leaking. rocker cover re-done, new muffler, and my water pump went [and when it went it went FAST!] This is the first thing to give me problem since then, maybe from me screwing around in a construction site? and just the rear leaf springs to get back up until I can afford a lift. Everything else has been things I"ve been adding. Got CAA for the trip across. Had to call for the first time the other day. Stupid me locked my keys in DOH!!! If nothing else, the beast has been dependable.

 

[Storydude]

That link is the Toyota TSRM. Think supra FSM. And they put about 600 RWHP to the AW4 in them before any damage happens. He's had that site up for 4 years now, and according to him, it's not going anywhere.

 

[cykaaro]

What are your thoughts on this?

Driving yesterday, and the gears were kinda of hesitating when it would switch. Wondering if the heat here is having anything to do with it, but then it seemed to go away. Went thorugh the gears to see if the others were doing it, and found my low gear was working again.Starting thing wonder if my power switch was working to. Tested it, and yep!, the power switch is now working again. As well, when I was backing up slowly with my door open, was hearing a weird sound, kinda of like a plate or something was loose? Mayhap it was just my muffler. not sure where the sound is coming from. Keeping an eye on it, but strange for sure. Have no clue what's happening with it.