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Vehicle: 1990 Liberty GX AWD Automatic Sedan

Any idea what would cause a 4EAT transmission to momentarily enter neutral while rounding right hand corners only?

In attempt to fix the problem I have removed the pan to clean the internal pickup filter and completely removed the external transmission filter. Also replaced the lock-up solenoid just because I had a spare. Of course completely refilled with new Nulon Dexron III.

TCU is not producing any fault codes. ATF level on dipstick is fine, maybe a little over full.

As a last resort I took it to a Transmission mechanic but he is baffled and suggesting I will need to find an exchange auto.

Thanks for any suggestions, Scott

center diff is had the bomb. Fit a fuse to the holder in the engine bay & go front wheel drive only and report back

seagull wrote:center diff is had the bomb. Fit a fuse to the holder in the engine bay & go front wheel drive only and report back

Thanks mate but auto trannys don't have a center diff they use a MPT clutch.

I also have a switches in the car to control FWD and MPT clutch lock up. I'm fairly convinced that neither of these functions are making the Auto transmission slip in right hand turns. Best way to describe the feeling is that the auto finds neutral for a moment before engaging drive again.


Cheers, Scott

I was thinking an intermittent short somewhere that only happens when the car is in a turn - wires swinging to one side and touching something, or wires being stretched. And that short causing the box to select nutral for a sec. It that even possible, I don't know much about autos.

Does it happen at all speeds? Walking pace?

Yeah definitely an odd one. I was thinking of maybe oil sloshing to one side and sucking air as this wouldnt produce a code. But you say its full, are you reading full when the oil is hot or cold?

I suppose the problem could be wiring but the symptoms don't 'feel' electrical if that makes sense. I have checked the loom from TCU to Transmission and found nothing obvious.

There are two sets of marks on the dipstick. I am reading full when hot.

Problem doesn't occur at walking pace.

Any more ideas? I'm stumped on this one.

I like the specialist aproach get another box. A mate was told to do same by similar and his problem was still there, oops, must be the TCU, so, another, still there, oops again. After a week and 2500 bucks someone found a corroded fusible link - was a Falcon though. Shame he didn't consult an auto elec first !!

I could drop in another transmission but this current one has only been in for a few weeks.

I'm thinking if I have to find another auto tranny then I might just as well do a engine/transmission transplant.

What's the go to breath some fire into the liberty? Remembering I need an auto for the missus. Should I find a donor wrecked WRX or XT forester maybe?

I had a very similar problem with a quad cam 2L 90 Legacy Wagon I had, on full lock right turn it would actually throw the lever into neutral, I never bothered to do anything about it as I didn't drive it much so I'm of no help, have you tried to see if it does it with the lever locked in 1st or 2nd, it felt mechanical to me too, almost like something hitting the shifter and the car would shudder when it happened too.

Happens in every gear regardless of selector position and most obvious on roundabouts.

Transmission slips out of gear and doesn't grab drive again until near the exit of roundabouts at the point where the turning forces start to reduce.

would a better term be 'neutralise' ? Wonder if it is something funny in the torque converter not the tranny itself ?? So, what if ....na, right turns only ??? So, what if you manually pull it down a gear before the turn to keep the revs/load up higher does it still neutralise then ?

'Neutralise' is term the transmission mechanic also used.

If I load up manually at the start of the corner and hold power all the way through the turn the gears remain engaged.

If at any point I back off or coast the transmission 'neutralises' until the car begins to straighten out of the corner.

Worst case is braking hard, turning in, then accelerating out. In that case RPM can easily reach 5000 before the transmission finds drive. But only in right hand corners!