4T60E Shifting Issue: 95 Cutlass Supreme

[MemphisMan]

A week after returning from the June W-Body meet, my transmission started shifting erratically between 2nd and 3rd gears.  From a dead stop, it would shift out of 1st normally, stay in 2nd for a split second, then shift to 3rd, causing my engine RPMs to go down until I got up to speed.  When I got my speed up, it would shift fine between 3rd and 4th.  I checked the fluid level and it was just under that "add" line.  I replaced the filter and fluid and it seemed to resolve the issue...until yesterday when it started doing the same thing.  The car has 85,7xx miles and the transmission has never been serviced.  Any ideas?

[vipmiller803]

I assume you checked the fluid again? Do you have tuner pro to check the temps and see the gear commands?

[MemphisMan]

I assume you checked the fluid again? Do you have tuner pro to check the temps and see the gear commands?

Yes, I checked the fluid, and unfortunately, it's full to the top mark.  I don't have tuner pro either :-/

[Leadfoot]

Does anyone local to you have a tech2 or other tool to help see what might be going on?  

 

When is the last time it was serviced?  Is anything else strange going on with the car?

[MemphisMan]

Nothing else going on with the car. I changed the transmission fluid and filter about 400 miles ago. It was doing the same thing before I changed the fluid, but stopped immediately after the change. Now, 400 miles later, it’s doing the same thing.

 

 

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[vipmiller803]

Well tunerpro might help you just in case the pcm is going nutso. If the commanded gear is different from where it's landing though, it might be time to dig into the trans...

[jman093]

From what I can gather, the issue is it's just not staying in 2nd long enough and shifting to 3rd way too soon? That's an interesting one. I agree with the tech 2/scanner route. Gear selection is fully electronic. The PCM commands shift solenoids on the e version. I agree and think you have to start out by watching with a scanner and see what the PCM is commanding to determine if something is causing the PCM to select 3rd when it shouldn't, or if it's not selecting 3rd and something in the trans is effed. Also make sure your early shift is not the TCC. The 4T60e usually locks the TCC before it's in 4th gear. I can't remember if it's during 2nd or 3rd gear. I want to say it's third though.

[MemphisMan]

On 7/21/2018 at 9:59 PM, jman093 said:

From what I can gather, the issue is it's just not staying in 2nd long enough and shifting to 3rd way too soon? That's an interesting one. I agree with the tech 2/scanner route. Gear selection is fully electronic. The PCM commands shift solenoids on the e version. I agree and think you have to start out by watching with a scanner and see what the PCM is commanding to determine if something is causing the PCM to select 3rd when it shouldn't, or if it's not selecting 3rd and something in the trans is effed. Also make sure your early shift is not the TCC. The 4T60e usually locks the TCC before it's in 4th gear. I can't remember if it's during 2nd or 3rd gear. I want to say it's third though.

Yeah, seems like it's not staying in 2nd for very long.  Looks like I gotta get smart on tech 2.  It's weird not driving it.  At least I got the AC working in the coupe and have been enjoying driving it.  More to follow when I start troubleshooting.  Thanks for all of the replies.

[55trucker]

On 7/21/2018 at 10:59 PM, jman093 said:

 Also make sure your early shift is not the TCC. The 4T60e usually locks the TCC before it's in 4th gear. I can't remember if it's during 2nd or 3rd gear. I want to say it's third though.

Can't speak for an OBDII environment but in an OBDI its lock up after 4th.

 

11 hours ago, MemphisMan said:

Yeah, seems like it's not staying in 2nd for very long.  Looks like I gotta get smart on tech 2.  It's weird not driving it.  At least I got the AC working in the coupe and have been enjoying driving it.  More to follow when I start troubleshooting.  Thanks for all of the replies.

How the the trans behave when you shift manually or place the shifter in 3rd locking out 4th or 2nd locking out 3rd?

 

[vipmiller803]

Do you have access to a tech 2? Tunerpro can read trans commands pretty cheaply. 

[GabsOlds]

Did you ever get to the bottom of the 2nd gear problem? 

[mfewtrail]

On 7/26/2018 at 8:47 AM, 55trucker said:

Can't speak for an OBDII environment but in an OBDI its lock up after 4th.

 

The converter will lock in 3rd even on OBD1 cars(4T60-E) around 40mph at light throttle cruising. If you have tunerpro, you can look at the parameters necessary for lockup to occur in either 3rd or 4th.

[GabsOlds]

MemphisMan, did you ever get this issue resolved? 

[MemphisMan]

9 hours ago, GabsOlds said:

MemphisMan, did you ever get this issue resolved? 

It's not resolved, but I haven't tried.  Work and family priorities haven't afforded me the time.  In the meantime, I've been learning all I can about the 4T60E.  

[GabsOlds]

25 minutes ago, MemphisMan said:

It's not resolved, but I haven't tried.  Work and family priorities haven't afforded me the time.  In the meantime, I've been learning all I can about the 4T60E.  

Ok. Plus you must be enjoying/fixing up the 5-speed coupe!  

[MemphisMan]

I had the transmission diagnosed at a transmission shop today.  There were able to connect to my ALDL connector and run diagnostic and troubleshoot.  They said all electrical was good and PCM was functioning as normal.  He said, based on what the car was doing when he drove it, that it was related to the torque converter.  Of course he recommended a full rebuild at a cost of $2100, which included all labor.  When I asked him if it could be the TCC solenoid, he said possibly, but recommended a full rebuild to be sure.  I'm going to check the ohms at the transaxle connector on Wednesday.   According to the service manual I should get between 20-30 ohms at pins A and D.  If not, repair internal wiring or replace TCC solenoid.  Solenoid and side cover gasket are less than $75 combined, so hopefully it's the TCC solenoid.  

[Imp558]

It costs me far less to do an L67/4T65e-HD swap.

The most I've ever paid for an engine /trans combo is $350.

Then cv shafts for parts and some other miscellaneous. Cv shafts have been the biggest expense. 

Not that I want to rekindle the 60* vs 90* thing, just pointing out the cost effective part. It may be cheaper to upgrade to a newer year in the 60* family and get into a 4T65 and have an abundance of replacement transmissions instead of the 4T60 though.

[MemphisMan]

I was able to test the ohms between pins A and D and it read 46.6 ohms.  If no between 20-30 ohms, service manual says to replace, so hopefully my issue is the TCC solenoid.  

[GabsOlds]

Sounding like the transmission didn't just die after all. Update us once you've replaced it. Hopefully before the end of fall. 

[Leadfoot]

I hope it's just the solenoid.  That would be far better.  Keep us posted.

[jman093]

That shop really doesn't have any clue, but honestly trans issues are pretty hard to diagnose since most everything is impossible to get to. They said it was "all electrical was good," but could they actually explain what it was doing? When it was apparently shifts into too high a gear or whatever causes your "rpm to drop" as you describe, could they state what gear was the transmission actually in and what is the PCM commanding at that time? In any case I would bet a lot of money the TCC Solenoid is not the issue. Keep us posted.

Edited September 16, 2018 by jman093

[MemphisMan]

On 9/15/2018 at 8:36 PM, jman093 said:

That shop really doesn't have any clue, but honestly trans issues are pretty hard to diagnose since most everything is impossible to get to. They said it was "all electrical was good," but could they actually explain what it was doing? When it was apparently shifts into too high a gear or whatever causes your "rpm to drop" as you describe, could they state what gear was the transmission actually in and what is the PCM commanding at that time? In any case I would bet a lot of money the TCC Solenoid is not the issue. Keep us posted.

The shop said the reason the car wants to die when I come to a stop is because the TC clutch is staying engaged against the flywheel, like when you come to stop in a manual and don't press the clutch pedal in, the car dies.  You're right jman, it wasn't the TCC solenoid.  Last weekend, I removed the transmission side cover to replace all four solenoids in there (1-2 shift, 3-4 shift, TCC, and PWM).  Same issue.  It was a gamble that didn't pay off.  

 

 

[Schurkey]

On 7/20/2018 at 5:46 PM, MemphisMan said:

it would shift out of 1st normally, stay in 2nd for a split second, then shift to 3rd, causing my engine RPMs to go down

Sounds like 2nd gear has failed.  Might be seals, might be hard-part failure.

[vipmiller803]

Did you ever confirm that the ecm is commanding 2nd gear when it shifts to 3rd? All I've seen is the shop saying the ecm is "acting normally".

Did you compare all the solenoid impedances?

 

[GabsOlds]

Damn! 

Hope you figure it out.