AW4 Solenoid Replacement write-up (no 56k)

[djlarroc]

Thanks for the info. Where do I disco the tcm? Or harness at the tranny? Will try it now.

Fluid smelled fine. I just recently changed it when I did filter change last week, and again last night w/the solenoid swap though.. And I agree about the meter. I'm sure I will need it in the future. I will grab that tomorrow tho...

 

[bigalpha]

In my 95, the TCM is under the kick plate on the passenger side. Not sure if it's on yours too, a quick search will yield answers.

 

[kastein]

On a 98 it's above the gas pedal on the tranny tunnel. Just unplug the wiring harness from it, you'll get two CEL codes relating to the ECU not being able to talk to the TCU via the CCD bus. Should drive fine. You'll get 1st in 1-2, 3rd in 3, OD in D, and no torque converter lockup.

 

[bigalpha]

Does 2nd gear shift at 5k RPMs in the later models too?

 

[kastein]

4500 on my 96 iirc. That's TCU functionality not tranny functionality though, you just plain get no second gear when you are running without a TCU.

 

[bigalpha]

Mine shifts into 2nd with TCU disco'd. Mine's a 95 though.

 

[kastein]

Interesting. When I disconnected the TCU on my 96 it went all the way to rev limiter (5250rpm or so) without shifting to second. I'll have to try that again sometime and see if I'm remembering it wrong.

 

[bigalpha]

Maybe it's different in later models? :dunno:

It's scary to have the engine revv'd up that high.

 

[kastein]

I generally hit the rev limiter at least a couple times a week when I'm driving the 96 to work for the hell of it... never hit the it in 3rd or above though, in 3rd that would be a wheel speed of 138mph.

 

[bigalpha]

It just sounds crazy. It freaks me out. a lot.

 

[djlarroc]

On a 98 it's above the gas pedal on the tranny tunnel. Just unplug the wiring harness from it, you'll get two CEL codes relating to the ECU not being able to talk to the TCU via the CCD bus. Should drive fine. You'll get 1st in 1-2, 3rd in 3, OD in D, and no torque converter lockup.

Thanks Kastein. So it will prob go to rev limiter, then go into 3? I'm just trying to see what to expect haha.

What do you guys think about the tranny code going away w/the solenoid swap? I checked the kickdown cable, and it's better than before, so don't think that's the culprit. Hearing the grinding has me worried though..

 

[kastein]

It won't do anything unless you tell it to - it might go to the rev limiter (or almost to it) and then shift into 2, but it won't shift to 3 till you put it in 3 and won't go to OD till you put it in D. If you try to start out in D you'll feel like the tranny is slipping a lot because it's actually in overdrive and with the torque converter unlocked it's pretty hard to get anywhere in overdrive from a standstill. You pretty much have to pretend it's a standard transmission, just with no clutch.

 

[djlarroc]

I see. That is exactly how it's driving now. If I put in 3, or D (OD) and accelerate, it feels like it's trying to move the truck, but won't move it. You can hear that grinding noise down there.

I put it in reverse, it goes in no problem. Put it in 1-2, goes in no problem. Once I manage to get it up to speed, it will drive normal and even downshift on the highway.. :wierd:

 

[bigalpha]

I see. That is exactly how it's driving now. If I put in 3, or D (OD) and accelerate, it feels like it's trying to move the truck, but won't move it. You can hear that grinding noise down there.

I put it in reverse, it goes in no problem. Put it in 1-2, goes in no problem. Once I manage to get it up to speed, it will drive normal and even downshift on the highway.. :wierd:

If it drives 'normally' with the TCM unplugged and you are manually shifting the gear lever, it points to an electrical problem, eg wiring, solenoid, etc.

When I got mine, I would put it in D but it would default to 4th gear as a safety device and it wouldn't go anywhere. I didn't get any grinding though.

Can you describe the grinding sound in more detail? An audio recording would be good.

 

[djlarroc]

If it drives 'normally' with the TCM unplugged and you are manually shifting the gear lever, it points to an electrical problem, eg wiring, solenoid, etc.

When I got mine, I would put it in D but it would default to 4th gear as a safety device and it wouldn't go anywhere. I didn't get any grinding though.

Can you describe the grinding sound in more detail? An audio recording would be good.

That's what I think is happening too. Likes it's defaulting into 4th. I can feel the truck trying to move when I accelerate, but since it's probably in 4th, it can't.

From what you are telling me, if I disco the TCM, it will keep driving the same? I've been driving it like this: 1-2, rev to about 4500, shift to 3, barely pulls, and finally once I'm at about 30 mph, it drives normal. I didn't get a chance to check, but sounds like a disco'd tcm. How great would that be! Then again, why would I get a solenoid code.

I'll try to get a clip of the grinding. You can only hear when it's in D, and you are accelerating from a stop. It's very minimal, but you can hear it. Can't hear it in any other gear.

 

[kastein]

Sounds like both your shift solenoids are bad to me, or a wiring fault, or a bad TCU. The grinding worries me, maybe it's the solenoids trying to pull in but not having enough push to actually do so?

 

[bigalpha]

Sounds like both your shift solenoids are bad to me, or a wiring fault, or a bad TCU. The grinding worries me, maybe it's the solenoids trying to pull in but not having enough push to actually do so?

All 3 solenoids were bad in my 95 when I got it. Replaced them in the dark in about 45 minutes.

Hard to tell without some DMM readings. Double-check your fluid level, too.

 

[kastein]

Yeah, that cursed dipstick tube is the worst part of the job. I'd probably disconnect it from the bellhousing (1 10 or 12mm hex bolt, I forget) and just drop the whole stupid thing far enough to swivel it out of the way.

Might as well replace the filter/pickup screen assembly and replace the RTV with a pan gasket while you're in there, it's ATP kit B112 at NAPA.

 

[bigalpha]

I spent about 15 minutes trying to get my dipstick off and couldn't, so I just let the pan half-hang there. No leaks as of yet.

 

[djlarroc]

Sounds like both your shift solenoids are bad to me, or a wiring fault, or a bad TCU. The grinding worries me, maybe it's the solenoids trying to pull in but not having enough push to actually do so?

Wouldn't I still be getting codes for the other solenoids though?

All 3 solenoids were bad in my 95 when I got it. Replaced them in the dark in about 45 minutes.

Hard to tell without some DMM readings. Double-check your fluid level, too.

I'm going to check the ohm reading on the solenoid I pulled out, today.

I guess I got real lucky. The other day when I did the filter change, the dipstick was not too hard to pull off. When I did the solenoid, it was pretty easy as well. It has a new pan gasket.

Fluid level was good.

Oh how I wish it was only the solenoids.