Tranny acting weird

Cajunhunter67 · Jan 19, 2013

I put this in Tech too, but figure I would find more help here.
Today I pulled out in Traffic. Truck shifted properly. Went into third gear and than nothing. I slowed, than tried taking off again, and it just rev'd. Hit the tow button, and it started to grab, but still slipping. I pulled off the road and turned the engine off. Cranked it back up. Checked the Tranny level, its about a half quart low. Back in drive, and everything is fine. I have it set on Xrace with Race lock on the Tranny. It started shifting hard and firm as usual. No DTC codes. Tranny fluid and filter has less than 4k miles on it. Tranny has 91k miles. Any ideas? This is the second time it has done it

3brorce · Jan 19, 2013

Sounds like a sticking solenoid or converter staying locked. This has happened to me before and I believe that is the issue. But mine I noticed it when I came to a stop and took off again in that it felt like converter was still locked

Cajunhunter67 · Jan 20, 2013

If the converter was locked, wouldnt the truck still move, just under a load at low RPM?
It definately could be a solenoid, but which one could cause this?
I have the direct drive GoGo solenoid. I was also wondering if the Tranny fluid pump was getting weak.

3brorce · Jan 20, 2013

If the converter was locked and you came to a stop I would think the truck would stall out. I would think that it would be your direct solenoid since you said it happened in third but not sure since you have the gogo. Hopefully someone else will jump in with some answers for ya

Cajunhunter67 · Jan 20, 2013

Im gonna return it to stock than reload the tune. Maybe a glitch. Will keep this updated.

3brorce · Jan 20, 2013

Ya thats a good idea. My LW sometimes doesnt load the correct trans tune. Have to load it a couple times just so the TCM takes the right tune

Mark Kovalsky · Jan 20, 2013

3brorce said:
Sounds like a sticking solenoid or converter staying locked. This has happened to me before and I believe that is the issue. But mine I noticed it when I came to a stop and took off again in that it felt like converter was still locked

It isn't the torque converter. That doesn't make any sense at all. If the converter is locked or unlocked it doesn't affect shifting into third gear.

Cajunhunter67 said:
If the converter was locked, wouldnt the truck still move, just under a load at low RPM?
It definately could be a solenoid, but which one could cause this?
I have the direct drive GoGo solenoid. I was also wondering if the Tranny fluid pump was getting weak.

Yes, the truck would still move but the RPM would be lower. The converter is NOT the problem here. It could be the intermediate clutch solenoid, that is the solenoid that applies the intermediate clutch for the 2-3 shift.

3brorce said:
If the converter was locked and you came to a stop I would think the truck would stall out. I would think that it would be your direct solenoid since you said it happened in third but not sure since you have the gogo. Hopefully someone else will jump in with some answers for ya

You're right about a locked converter stalling the truck when you come to a stop. You're wrong about the solenoid, the direct is not used in third gear. The intermediate solenoid is used for third gear.

Cajunhunter67 said:
Im gonna return it to stock than reload the tune. Maybe a glitch. Will keep this updated.

Good plan.

3brorce · Jan 20, 2013

The trans tune he is running I am pretty sure locks in third. When is direct applied?

Cajunhunter67 · Jan 20, 2013

I re-installed the tune. Seems to be shifting great. Next step will be as Mark said...Intermediate Solenoid. To bad they dont make a modified GoGo for it.
Seems if the Tranny was slipping (Clutches going bad) it would continue regardless of re-installing the tune.
I believe the Direct is 5-6, and Reverse. I could be wrong.

Mark Kovalsky · Jan 20, 2013

3brorce said:
The trans tune he is running I am pretty sure locks in third. When is direct applied?

The direct solenoid is used in 5th, 6th and reverse. 4th and 5th for those that don't know this is really a six speed that usually skips 4th gear.

Tree Trimmer · Jan 21, 2013

what are teh circumstances that would make it hit 4th gear??

09stroker · Jan 21, 2013

Cold oil temps

3brorce · Jan 21, 2013

^^^ yup when trans oil is cold she will go through all the gears even though I have never felt it

Cajunhunter67 · Jan 21, 2013

Mine would go into 4th and get stuck until I turned the key off and cranked again. Changing the direct solenoid fixed that issue. Under normal circumstances, Im not sure what brings the tranny to shift to 4th. Its always a 3-5th shift.

Mark Kovalsky · Jan 21, 2013

When the trans is colder than 0°F it uses 4th (1.09:1 ratio) instead of 5th (1:1 ratio.) It does this because it is MUCH easier to do a 3-4 shift instead of a 3-5 shift. At cold temps we couldn't get the 3-5 shift to work right every time.

So cold it shifts 1-2-3-4-6. Once it warms above 0°F it shift 1-2-3-5-6.

It will use 4th gear at any temperature in a certain case. If the truck speed is too high to shift to 3rd gear when you floor it, it can select 4th instead of 5th. There is a very narrow window of speed that it will do this, once it gets several MPH above this speed it will go to 5th, not 4th. The reason for this is that it gives 9% more torque to the wheels than if it was in 5th, plus the engine is spinning a bit faster. That also gets some more torque.

If it does select 4th it can only upshift to 6th or downshift. It never, ever will shift 4-5 or 5-4.