sventinker

Hello all, I have searched the threads and feel my difficulty is thread worthy, I purchased my 96 limited 4.0L with a new lift and 35" tires It had a problem of dying after 30 minutes of driving, replaced the sensor in the distributor and it never dies now. After two weeks of ownership I was headed home and The trans suddenly felt like it was in neutral I had to come to a stop. When I pressed the gas it continued to drive but was stuck in first or second. I then stopped for fluid assuming it was low but found it was over full. with cycling the key off and then on it then shifted fine all the way home. It sat for the weekend as we were busy.

Now Monday morning it then got stuck in third, no downshifting or overdrive the way home it was fine. I also adjusted the cable on the throttle body before the drive home (was off by one click) So last night I changed the trans filter and fluid and the pan was spotless, the filter was clean, and the fluid looked good. The gasket was old indicating it hadn't had a recent service. Test drove it after and it shifted smoother.

This morning it did the neutral thing again I had to stop turn off engine, restart and it operated normally all the way to work. At lunch in the drive through it was stuck in third and I drove it back to work (very close). The way home it drove like a lifted dream! The tps has been changed as a attempt by the PO to rectify the stalling. I have the gear on order to fix the speedometer as the speed is off with the large tires. I was reading a thread on here that shows the pin out of the tcu plug to ohm the solenoids and other stuff but I can't seem to find it tonight. It has not thrown a code and I priced all the stuff people say to try and I don't want to play the trial and error method as these parts aren't cheap. any help is very appreciated.

arorton

Mine did the same thing, staying in third.. it eventually decided to rectify itself, but if anyone has additional info I'd be very interested to hear it

sventinker

Also to add insult to injury I just read on here that it is supposed to take dex/merc not the atf4 the guy at autozone sold me.

arorton

Yes, definitely use dex/merc

Radi

If it works fine for a while after cycling the ignition key, I'd be suspicious the TCU is on it's way out the door.

SweetLou

Maybe one of the solinoids is going? I had to replace mine because it wasn't shifting properly, took forever for it to throw a code.

sventinker

How do I test the solenoids?

lgrant

I have a very similar problem. Most of the time, my tranny will shift fine but my historical problem is that on the freeway, the tranny will occasionally just shift into a lower gear and the engine revs like crazy - actually kinda hard to explain. And I also lose lockup on the TC. I'm thinking it might be a wiring problem - maybe the ground wire coming off the solenoid(s)? I say ground wire because I have a switched hard wire to solenoid c for the lockup when I get up to speed. It worked great (kinda a pain in the ***) for about 25K miles and recently has become fussy - most of the time it won't work. Either an obscure ground wire problem or I've worn out the TC lockup clutch.

The link below will give instructions for an ohm test. It's a start.

http://www.transonline.com/transdige...ers/index.html

sventinker

Thanks, ever since putting in the atf4 the trans is working fine. Which leads me to think I have a solenoid sticking. I assume the atf loosened up some gunk.

lgrant

After posting on Monday and thinking it had to be a wiring issue, I took apart the two transmission wiring connectors under the hood near the dipstick (one gray and one black) for inspection and cleaning with electrical parts cleaning spray. They looked just fine but I sprayed them anyway. While it hasn't impacted the TC lockup problem (probably a bad solenoid), it seemed to fix the random shifting problem - hasn't missed a beat since Monday when I did it. I probably have 150 miles on it since then. The random/failure to shift problem was at both low and freeway speeds. Sure is nice to drive an auto trans that is auto.

dubbydoo

i had similar issues it would stay in gear and feel like its in neutral till i got to about 3k then it would pull and i would have to rev it out to get it to shift turns out it was the tps sensor i was driving a 94

sventinker

My tps is new, ill check those plugs. Thanks guys

sventinker

well I gathered all the bits to finally make this so here it is. I made it for 96 and earlier aisin warner Transmissions. I took a old TCU and un-soldered the female plug and mated it with the male plug from a junker. I attached pigtails for molex plugs so the unit can be unattached leaving the harness in place. There is a provision where the ignition hot input is switched through my diagnostic tool as I suspect I am losing that signal intermittently while driving.

Each function of TCU is represented by a colored LED and a voltmeter connected via a 11 position rotary switch. There are 10 functions I am reading and I left an extra position for an addition that may come up. The Functions are as follows.

1. torque converter lockup
2. shift solenoid #1
3. shift solenoid #2
4. Brake switch
5. shift lever position 1-2
6. shift lever position 3
7. constant hot
8. ignition on
9. Throttle position sensor (TPS)
10. Trans output speed sensor

There is also a ground and a TPS ground. The TPS ground must be used for the TPS signal LED to work I cannot read the voltage on this one function because the voltmeter uses the common ground. I will have to use a separate voltmeter If I want to read the voltage but the steady glowing increase of the LED is sufficient for now as an analog needle would be preferred for that function anyway.

The constant voltage to the Tool is switched so I can leave it in the jeep without a draw on the battery. The second toggle switch is so I can interrupt the ignition voltage and switch it to the constant voltage. This was done because when I have my intermittent problems the problem can be remedied by cycling the ignition and now I can do this without killing the engine.

To sum it up I can see when the Torque converter is locked, what gear I am in, The output sensor signal, and the other stuff listed above. I also will know if I am not in a gear the TCU is telling it to be. One more plus is where I dont have a stock clock I will permanently install LED's for the gear and torque converter with a manual locking switch that will automatically unlock in first gear so as to avoid stalling the options are great for manual control. Can you say paddle shifting? Manual or auto mode would be killer.
The total cost were around $50. and I could have done it under $20 if I didn't have to source the TCU plug from a junkyard via mail. I need to add labels so I wont forget what is what. Here are the pics.

sventinker

Here is a short video of it working

sventinker

one more video a little longer more detail