GL/Loyale 4EAT Problems... Where Is The TCU???

[NorthWet]

90 Turbo Loyale wagon with a 4EAT. Wife was driving to work and out of the blue the tranny quit transmitting any (noticeable) power. Engine revved freely, did not matter what gear the shifter was placed in. Wife came out a few hours later to try to better park the car, and it moved, though not as it should.

 

I came out several hours later, checked the ATF (a little dark but not smelly, and actually somewhat overfilled), put the car in reverse and although it sluggishly shifted into reverse it did so, allowing me to back out of the space. I put the shifter into 2nd (don't know if I pressed "1st hold"), the engine revved before the tranny completed the shift, and I got a sharp "chirp" from the tires. Drove a couple hundred feet and reparked the car. Tried to limp the car home, got a mile or so and it quit tranmitting (felt like it was maybe tranmitting 2-3% of the power). Stopped, rechecked connectors and fluid level, got sworn at by irate rush-hour drivers. After about 5 minutes, started the car to try and limp it to parking lot, and it worked fine again. Using a run awhile, turn off and wait awhile method, got it limped home, including up a couple pretty steep grades. When the tranny was working it seemed pretty solid.

 

It does not seem to be an overheating issue, as turning the engine off for 3-5 seconds is enough to get me 30-60 seconds of decent running. It also seems to be somewhat related to shifting gears (though not strongly, as if I use "1st Hold" and selector in "2" problem still occurs). It is as if either the electricals need to get reset or a clog/restriction in the fluid circuit gets temporarily resolved/relieved.

 

I have changed the ATF (including adding ATF, restarting, and redraining to help change fluid left in TC), but this has not as yet made a difference.

 

I was planning on swapping out the TCU, but have not figured out where they put the TCU.

 

Any ideas or suggestions to fix/diagnose this problem?

[idosubaru]

i'd imagine this is in the same place as the XT6 TCU. it's behind the drivers side rear seat side panel. remove the panel and the TCU is semi-tucked away behind the metal shell. that's where the XT6 is and i have a suspicion this one would be as well.

 

first check the transmission pan. the sump is REALLY tight to the bottom of the pan, if the pan is dented you could have restricted oil flow. doubtful, but easy to check.

 

if the TCU was to blame i'd suspect a blinking POWER light when you start the car, but wouldn't be too surprised if it didn't either. if it is blinking, find the procedure for pulling the TCU codes. it's a rediculous procedure but would be very good to know if the POWER light is blinking that indicates it has a stored code.

 

i'd pull the transmission hose and bypass the radiator, it could be clogged. install an aftermarket transmission cooler or just run one hose from and to each inlet/outlet of the ATF pipes to temporarily check it.

 

i'd start looking for/keeping your eye out for another trans in case....

[NorthWet]

Gary!!! Thanks for the quick response.

 

The pan did look a little depressed when I was under there changing the ATF. I haven't yet pulled the pan to look inside, as the local auto parts places do not carry gaskets for the 4EAT, and a gasket and "filter" kit is over $35... all special order from BFEgypt. Think it is worth pulling and take a look (and then replace/fix gasket with RTF)?

 

POWER light has blinked since I bought the beast. One of the NewGen folks (Josh?) had given me the extraction procedure some time ago... I saved it on my computer somewheres... It is a silly procedure.

 

I also had thought of bypassing the cooler; just need to find the time and convince my wife to let me spend the money.

 

Have you heard of any problems with the TC stator failing? One of the more esoteric thoughts that I had was that if the stator didn't work properly that the TC would not transfer properly; I have heard of this issue in domestic trannies.

 

Thanks again!

Pat

 

Oh, and I do have a spare. Just looks like all of my options for making my wife happy start with "remove transmission".

[idosubaru]

i think i'd try to extract those codes before doing anything else to the car. if it's flashing, the TCU knows something and that will only help you.

 

just get a long piece of transmission hose and run it from one side to the other. did it to my grandmothers car a few weeks ago when her radiator ATF cooler sprung a leak. ran fine. for the cost of hose you rule out the radiator.

 

one minor bump in the pan shouldn't cause alarm, but a big dent might be worth looking into. got any large magnets to pull it out? drill a hole and pull the dent out, then weld it back shut. that would be quick. pulling the pan is very annoying as the old gasket will be caked on, hard to get off and the new gasket likely won't seat right on the pan because the screw holes are all non-flat. they get concave so to speak and end up making the new gasket leak in short order. really annoyihng...just like oil pans if you've done those.

 

should be able to order just the gasket for a couple bucks, i've bought them before without issue. but that being said...you might be better off replacing if not the filter, the o-ring at the top of the filter. the filters really aren't worth replacing because they aren't much of a filter. they are only a screen, a fine mesh screeen and i've never seen one have so much as a fleck of dirt in them. i've replaced them but have to be honest and say i've never seen one that needed it. so if you're not wanting to spend the $, then don't you won't suffer for it. but....with your issues i might want to look at the o-ring that goes on the filter where it slides up into the trans pump. there's an oring around the filter outlet. maybe that's causing loss of pressure to the system?

[NorthWet]

Well, I found the code extraction procedure... given to me over a year ago by grossgary.

 

First use of the procedure netted me Codes 7, 8 and 11; Duty solenoid B, C, and A, respectively. After restaring car and then rechecking codes, all I seem to have now is a Code 11, duty solenoid A. Now, if I can only find the manual that I saw the tranny internals in...

[85Sub4WD]

I have an XT service manual that covers the 4EAT - duty solonoid A is in the val ve body (surprise) - it controls the hydraulic pressure in the tranny - if it is stuck open, you wont go anywhere - I'd check the connectors first, before trying to pull the tranny apart

according to the troubleshooting table - it says the error code generally indicates "severed solenoid or short circuit, severed wire harness or short circuit"

[NorthWet]

Much thanks, 85Sub4WD. Sounds like it could cause my base problem. I checked the gang connectors up near the tranny/engine juncture, but haven't crawled back under to look for individual connections for the various bits and pieces.

[idosubaru]

friend of mines explorer wouldn't get out of 4WD and i crawled under the truck, found a mysteriously cut wire. spliced it back together and all was well.

 

i'd keep checking the codes...wondering if those others were residual or legitimate. if they are actual codes, all three, then i'd definitely expect a wiring harness plug or wiring somewhere. many squirrels/mice around your place? they like to chew on wires.

 

also wondering if the TCU has issues if it's multiple circuits showing up. didn't you have at least one (if not two) vehicles with a cracked/broken rear window? the TCU is located directly underneath the rear window on the drivers side in an XT6. i'd wonder if any glass or water could have gotten on it/in it and caused issues if this is one of your cars with broken glass.

[NorthWet]

Two of the 3 codes I got cleared after the first iteration of pulling codes. Only the DS-"A" issue remained after several rechecks.

 

The description of the DS-"A" code that 85Sub4WD gave seems to match my issues pretty well. I finally got to pull the TCU and it looks dry and in good physical shape except for some fine dust all around it and some in it. BTW, in a 90 Loyale wagon it is just above and behind the left-rear wheel well under the interior trim panel.

 

I took the car out for a test drive yesterday, and my feeling is that it is improving, that I can get the tranny to engage and stay engaged for longer and in several of the gears. IF I try to pass to much effective torque through it (like stepping on it in high gear), the clutch packs will start to slip. I am hoping that I just have a sticky DS-"A", and that the clean ATF, some SeaFoam, and alot of patience will clear the problem.

[idosubaru]

sounds like it's in the same position as the XT6 TCU, probably alot of the EA82, if not all are located there.

 

glad it's going away...hopefully the new fluids does the trick.

[guido32]

Had same issue with my wife's XT4 Subie specialist advised tranny was gone so I replaced with 3at just my 2cents. best of luck with your fixes

[NorthWet]

sounds like it's in the same position as the XT6 TCU, probably alot of the EA82, if not all are located there.

 

glad it's going away...hopefully the new fluids does the trick.

Through a can of Seafoam in it yesterday and then drove it the 50 miles roundtrip to my night job. I really had to play with the gear selector on the way out, mostly keeping it in 3rd. Did better on the drive home, tolerating "D" a little better, but still getting confused if I gave it a little more power. Right now, it is acting like a 3AT with governor issues. so I suspect that some of the internal valving is still a little gummy. But it is definitely trending towards getting better. Just got to make sure I don't toast the clutch packs through impatience.

 

Thanks y'all!!!

[idosubaru]

awesome, glad it's getting better. if you remember to post a follow up in a couple weeks/months i'd like to hear what comes of it.

[NorthWet]

Status: Still broken.

 

This is driving me nuts. I can get it to run reliably in 1st, fairly reliably in 2nd, so-so in 3rd, and 4th is a crap-shoot. It acts better on my drive home at 3-4am than at 7am, 3pm, or 6pm. Why it acts better in the middle of the night escapes me.

 

So far I have changed the ATF once (including Seafoam), checked the cable connectors (but not continuity on them yet, swapped-out the TCU, bypassed the tranny cooler using an Aerostar tranny cooler.

 

I am still getting a error code 11 (reportedly Duty "A" solenoid). My next step seems to be to pull the pan and check that all is well around the valve-body and pickup. I would also like to check the Duty "A" solenoid, just need to find where the DAS is located.