What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Odd problem in OD** TC Unlocking/Locking, Update Post 14

jonathon

jonathon

1/2 ton status
Joined
Jul 22, 2007
Posts
1,877
Reaction score
1
Location
Washougal, WA
I'm noticing in my 'burb when I'm in OD doing anything less than 70 it seems to be either shifting or the TC is unlocking/locking. I can hear the engine RPM's change, and it's something that happens over and over again even on a flat stretch.

I'll have the cruise set and be doing 60 and I'll hear the exhaust smooth out. Then I'll hear it pick back up again, and then repeat. Don't "feel" it at all other than the sound. It stays steady in 3rd and when in OD at 70.

Since I don't have a tach I haven't totally decided what it's doing, though I'm leaning towards something potentially to do with the TC lock up since it doesn't feel like it's shifting.

Now, I think I could've bumped something when I had to replace the distributer shaft, but I'm not sure. Is there any sort of adjustment on the 4L80E at the throttle body for proper shifting?

This worries me.
 
Last edited:
Check your ATF level, it might just be getting weak too. Dont let it do that to long though. That engage and disengage creates heat and thats what kills 700s
 
The 4l80 is fully electronic and doesn't have a TV cable like a 700r4, so you couldn't have bumped anything.

The only way to know what's going on for sure is to connect a scan tool and see what's changing.

It's a longshot since it doesn't get very hot in your neck of the woods but could it be the clutch fan engaging and making the noise you're hearing?
 
I'm not sure that it's the fan, the Flowmaster makes it hard to miss :crazy:

Trans fluid looks good, but I'll double check it to be safe. The other thing I forgot to add the trans only has 55K on it since new, dealer replaced it in 1998 and it has been well taken care of(Two flushes in it's life and I'm going to flush it at the end of August). When I have in 3rd, I have no issues at all.

I do still need to replace my wires and my coil, so perhaps that is it(still stumbles under load, but that's because of how badly corroded the coil is I think).
 
ah hell i didnt even look to see the specs...shoot
 
Drey said:
ah hell i didnt even look to see the specs...shoot
Click to expand...

I imagine heat kills either just the same :crazy: Been running it in 3rd since I noticed this(I don't think it did that before).

I do sorta wonder if it's a change in the TCC.. the change in noise in the engine is not quite as dramatic as a down shift into 3rd. One thing I haven't tried yet and just thought of was when doing 60 in OD shift it down to D and see how it feels.
 
jonathon said:
I do still need to replace my wires and my coil, so perhaps that is it(still stumbles under load, but that's because of how badly corroded the coil is I think).
Click to expand...

Do a complete tune up and replace the bad coil and wires. A poorly running engine can make the TC lock in and out at cruise.
 
jonathon said:
Trans fluid looks good, but I'll double check it to be safe. The other thing I forgot to add the trans only has 55K on it since new, dealer replaced it in 1998 and it has been well taken care of(Two flushes in it's life and I'm going to flush it at the end of August). When I have in 3rd, I have no issues at all.
Click to expand...


flushing the trans is good but you also need to drop the pan and change the filter every once in awhile
 
Thunder said:
Do a complete tune up and replace the bad coil and wires. A poorly running engine can make the TC lock in and out at cruise.
Click to expand...

I'm almost 90% sure it's the coil after playing with it today... scrounged up the money to buy an MSD stock replacement and new wires tomorrow. It's doing it in 3rd also and I'm sure it's TCC lock up. It has a new cap, rotor, ICM, and shaft in it now.

My budget was murdered by the need of a shaft :crazy: The magnet on the shaft fragmented and took out a lot of stuff under the cap including the pick up.

I was stopping to get the mail and I kept hearing a snapping noise(like a short). I could see sparks coming from the coil :eek1:
 
Duntz00 said:
flushing the trans is good but you also need to drop the pan and change the filter every once in awhile
Click to expand...

Doing the filter too..

I'm going to service the cooling system and trans all in one shot since it'll be easy with a new rad and trans cooler to flush it. Just have to wait till the next pay check..

Any idea on how much fluid the 4L80E takes?
 
I would also recommend a fuel filter with the tune up parts listed by Thunder. I've heard many stories of electronic trans "problems" that turned out to be fuel or ign problems, usu regular maint items. I hope it's that simple.
 
Okay maybe not.. it seems to be okay once the truck warms up(still a little touchy), but the torque convertor locks/unlocks randomly still in both 3rd and OD :crazy: Once the truck has been driven a few miles it seems better, though it'll occasionally kick out of lock up.

What's going on to cause the TC to do this? I'm positive that is what it is doing.
 
Everything that is there is plugged in.. not sure what is what though. It is a 4L80E.

Anyone have any ideas? What controls lockup on a 4L80E? Where should I start? I need to get this figured out, I don't want to cook my transmission :(
 
I have this same problem with my 700r4, it seems if I ease it into OD it is fine, but when I hit the brakes it wont lock up again. I have thought about replacing the whole harness, but I'm not sure where to start. It worked fine before I did the trans service and everything is hooked up.

I have been looking for a diagram but can't find anything.
 
I had no problems on the way to work, but it's 8 miles to the highway of driving in 3rd(not OD), so everything is good and warmed up. I'll see how it is tonight since I get on the highway almost right away from work...
 
What controlls the tranny? Factory PCM or a stand-alone transmission controller?

Anyway, lockup should be decided by manifold vacuum, vehicle speed, rpm, gear and coolant and/or tranny temp. If you get errors in any of these signals you will get errors in the lockup behavior.
 
You must log in or register to reply here.

Latest Posts

Top Bottom