Ralls

iTrader: (32)

I did a 4L80E swap from a 4L60E into my 94 LT1. Everything is brand new. New Jake's Performance 4L80E, new Circle D converter, and new 4l80e harness from PCM to trans. The TC is not locking up. No DTC's. This is the diagram to my PCM http://shbox.com/1/1995_pcm7.jpg and http://shbox.com/1/1995_pcm_conn_d.jpg Here are some things I found:

-4L80E TCC PWM solenoid wire going to PCM D11 (TCC solenoid control) has 12volts on it with key on

-11ohms across D11 and 4L80E 12v power wire. This should prove there is a 11ohm TCC PWM solenoid there.

-Can hear solenoid activate when grounding D11 with key on engine off

-Does NOT lock converter when manually grounding D11 while driving.

This part really confuses me. For some reason I do not have a wire going to D6 (TCC PWM). I did not remove it. When I had the 4L60E the converter locked. So how does it make sense there isn't a D6 wire?? I know you don't use D6 for the 4l80E but this still makes absolutely no sense to me.

So what do you all think? If manually grounding the TCC doesn't lock it implies a mechanical problem correct?

Jake's Performance

iTrader: (2)

Check your wiring. I can say we watch for lockup on the dyno and the converter internally, lockup is pretty simple.
The 4L80E needs 12V to the E wire on the main connector and ground to the brown wire on a stock harness, I can't remember offhand which letter it is, I know it by pin location.

Ralls

iTrader: (32)

I double checked the wiring. D11 wire is going to Pin S on trans connector. I even checked continuity from D11 to S to verify it's the same wire. I have my 12v power on D11. So now what?

Jake's Performance

iTrader: (2)

D11 (S) must be grounded to activate the lockup.

You will see power on it when the key is on because power is going to the TCC solenoid from the E wire, through the coils in the solenoid, and out the S wire. You must ground the S wire to pull the solenoid in.

Unhook the S wire from your PCM, and manually ground it while moving in 2nd gear or higher to test the lockup. This eliminates the PCM and tuning from being a factor.

Ralls

iTrader: (32)

I understand all of that and I just did it again to be sure. I grounded S manually while in 4th gear on the lift. The RPM's do not change what so ever and it still feels like a loose stall when you blimp the throttle. I can ground S with the key on engine off and hear the solenoid "click" inside the trans.

I also hooked up a test light to 12v and pin S and the light comes on in 4th gear. So the PCM is commanding lockup.

Everything is checking out ok with the wiring. Sounds like a mechanical issue to me. Is it the converter or transmission??

Jake's Performance

iTrader: (2)

Have you tried it while actually driving it yet? I wouldn't go by what you see on the lift, the transmission can be in overrunning at the OD sprag with no load and you won't "see" lockup even though it's actually occuring.

Try that first, then if it's not locking up, pull it out, pull the converter and be sure the o-ring on the input shaft isn't damaged. After that it would be time to start shipping stuff back so we and/or Circle-D can check it out.

Ralls

iTrader: (32)

That was actually my next plan of attack. I kinda figured it being on the lift would be different than on the street with a load. I did drive it on the street, just not when manually grounding the TCC. I was going to do this today, but it's been raining.

I sure would hate to have to pull it back out and waste trans fluid and more down time. Gotta do what you gotta do I guess. Thanks for the help so far. I'll let you know what I find.

Ralls

iTrader: (32)

Ok I manually grounded the TCC while driving to no avail. Time to pull it all back out

joecar

Is your PCM unchanged (i.e. it was the one used for driving the 4L60E)...?

You have to check and/or make these changes (referring to your PCM-trans wiring diagram):
- remove B13 from S (3-2 control),
- remove D6 from U (TCC PWM),
- move D11 from T to S (TCC solenoid),
- insert a relay between B12 and B to invert the sense of the signal (2-3 shift).


4L80E uses one TCC signal: TCC PWM.

4L60E uses two TCC signals: TCC solenoid and TCC PWM;
to lock the TCC, the PCM drives TCC solenoid on and TCC PWM to 100%;
when the TCC is unlocked, TCC solenoid is off, but the PCM may sometimes park TCC PWM at 90%, so you can't use 4L60E TCC PWM to drive 4L80E TCC PWM.

The 4L80E 2-3 shift signal is the inverse of the 4L60E 2-3 shift signal, so you have to insert a relay to invert the signal.

4L80E does not have 3-2 control solenoid.

joecar

More info:

4L60E:
S = 3-2 control
T = TCC solenoid
U = TCC PWM

4L80E:
S = TCC PWM <--- drive this from 4L60E TCC solenoid

joecar

More info:

4L60E:
2-3 shift solenoid sequence 1-4 is: on, on, off, off.

4L80E:
2-3 shift solenoid sequence 1-4 is: off, off, on, on.

Ralls

iTrader: (32)

I've done all of that joecar, thanks. The trans shifts through all gears fine. Just doesn't lock the converter.


However, when does this information get applied?:

joecar

That information is applied as the PCM sequences the trans thru the gears (1st, 2nd, 3rd, 4th).

If your PCM is unmodified from the 4L60E, then the 2-3 shift solenoid signal is inverted and the 4L80E cannot shift correctly, unless the harness already does something about this (a relay) [ if it shifts correctly then this may be the case ].

joecar

Hmmm... can you access a scantool with bidirectional ability...

if so, form the scantool you can command the TCC solenoid on (not the TCC PWM) and check to see if you hear it click.


Is your PCM unmodified and unedited (you did say it ir was or wasn't)...?

Ralls

iTrader: (32)

Hey Jake, I pulled the trans and the input shaft o-ring is still good. I'm sending the converter to Circle-D to see if they find anything.

PCM is still tuned for 4l60e and I did all the wiring changes with relay. Yes the TCC solenoid activates when manually grounding

joecar

No... I mean can a scantool command it (i.e. from within the PCM)...?

Ralls

iTrader: (32)

Being OBDI I don't think my software can do that. Regardless, I verified the PCM is grounding S by hooking up my test light while driving.

joecar

Hmmm... yeah you're right...


since you can manually ground it, then that leaves the PCM not being able to do it.

joecar

On the ALDL port isn't there a pin that indicates when the PCM commanded the TCC...?

( wow, this has been a while, I only seem to vaguely remember )

Circle-D

iTrader: (21)

Sorry, just saw this thread. Thanks for calling last night. Be happy to check it out and will let you know what we find. Sounds like you have covered all your basis electrically, so probably a mechanical issue.

Chris