AW4 torque lockup not disengaging when changing from 3rd to 4th--normal?

[ehall]

All the AW4's have a solenoid for the t/c lockup, so it's a safe bet that the TCU would still be able to lock the t/c.

I'm not having a problem with lockup solenoid, I'm having a problem with hard shifts from 3rd/lockup to OD/lockup. This mode is not a normal part of the shift sequence after '91 so my question is whether the '94 valve body supports it.

I have a 99 AW4 running with an 89 TCU and it locks up just fine. Only issue I had was the difference in the rear output shaft speed sensor.

Do you run it in Comfort or Power mode?

 

[lawsoncl]

Gotcha. It does seem odd that it's not bothering to unlock the t/c when upshifting. I typically run mine in power.

 

[ehall]

Gotcha. It does seem odd that it's not bothering to unlock the t/c when upshifting. I typically run mine in power.

I used two different '91-specific TCUs and both of them command 3rd/lockup to OD/lockup in Comfort mode so it seems that lockup not disengaging is "normal"

Power mode uses 3rd to OD then OD w/ lockup, and that does not have a problem. Try your setup in Comfort and see if you can detect the sequence.

 

[Ecomike]

Gotcha. It does seem odd that it's not bothering to unlock the t/c when upshifting. I typically run mine in power.

As I have already said below, my custom idiot light on my TC lockup power from the TCU to the TC LU solenoid does not disengage between 2-3, 3-4 shifts! It is a clutch pack(s) that does the smooth (or in his case not so smooth) shift. There is no reason for the TC to unlock during upshifts! At least that is my take on having read the AW4 manual multiple times.

 

[ehall]

Since I wasn't getting anywhere, I figured the transmission might have simply been caked with dry and dirty fluid after sitting in the salvage yard's warehouse for a few years, so I added 9 oz of Auto-RX to the fluid and drove it for about 1500 miles (the manufacturer suggests 6 oz for 1000 miles but I figured they weren't allowing for caked fluid). Auto-RX is not a detergent or active cleaner, but is an ester treatment that soaks into the metal and pushes crap off the walls from behind. I figured that this stuff in conjunction with the detergents in the Dexron VI fluid ought to get the thing pretty well clean.

Yesterday I changed the fluid while swapping the tranny cooler, and the results are quite remarkable. The stuttering shift from 3/lockup to 4/lockup is almost completely gone and is still only perceptible because I am hyper sensitive to it. The hard shifts from drive to reverse and vice versa are gone as well. Overall shifts are as smooth as my Cadillac. Very nice results. I will probably do another fluid swap and also change the filter screen in another few thousand miles so that I can get whatever junk is left out of the system.

So I'm guessing that the valves were caked, and the thing just needed a good cleaning.