Denali08

That's because ur truck is EC, same length as 2500 Duramax trucks.

Let me know u if find that billet 4wd shaft and we can work out something.

Denali08

Got the truck out of the trans shop after putting the RPM 4L65E level 4 in, swapped the 2WD output shaft with my stock 4WD shaft. Will have to get a billet output shaft for future swap.

After test driving it around the block with the trans builder, I left and headed to the highway to home after he said it's good to go.

On the road to home, I noticed that it shifts down from 4th to 3rd cruising at 75-80 mph then to 4th and son. This is with shifter in D position.

Also, when in shifter is in 3 driving from a stop, it would stay in 2nd and rev hi until I shift it to D then it would shift normal to 3rd then 4th. In fourth, it would shift back and forth between 3rd & 4th cruising as mentioned 75-80 mph.

Is this an issue with the transmission or something in the tune that I should have it corrected.

Any help is appreciated.

2ktransam

iTrader: (12)

I didn't think about that. I guess it would be hard to stuff my exhaust in a reg cab. The muffler is huge.

I found my billet shaft. I will pm you.

Heads-Up-Outlaw

It could easily be related to the tune. But, the key to understanding the symptoms better is to get a scanner on it and drive it while it's acting up. Look to see if what you are feeling is actually being commanded or not.

I suspect it's a situation where the PRNDL switch is not adjusted properly. Also, are you sure it's not just unlocking/locking the converter at highway speeds?

g

Denali08

I think ur right about it locking & unlocking the converter because my RPM at that speed would never be as high as 3rd gear.

I have HP tuner but I rarely use because I am not that keen on learning tuning although I have the tuning school tune at home course.

I am taking it back tomorrow to the trans shop to check it. meanwhile, what to check for exactly using VCM scanner??

Heads-Up-Outlaw

What you re looking for is the TCC solenoid on/off reporting.

Also, look for the shift solenoids to activate or not while this is happening. I'll bet you'll find it's related to the torque converter clutch.

But, that does not account for the lower speed issues. I would want to see what the converter is doing there too. But most importantly I would want to know if the PCM is reporting the correct shift lever position.

g

Denali08

I went for a ride and done a scan. Log file attached.

I could not find out from the scan log anything about the transmission lock up. But I discovered indeed that it's my lock up convertor locking and unlocking. When it sort of downshifted, I moved the shifter to third and down shifted one more step, so, it was already in 4th not in 3rd but it was locking & unlocking alternatively.

Also, check engine code showed and there was error code P1810. I reseted the error code and it didn't come back again.

I read that this P1810 is related to TFP Valve position switch circuit/trans 4-wheel drive low inicator short circuit to battery.

Is this related to tranmission valve body or to 4WD low indicator? I was in 2WD mode when it showed up.

03sierraslt

iTrader: (22)

Post up a log and your tune, or a screen shot of your trans tables.

Denali08

Oh.. shxx. I forgot to attach the log.

Here it is.

Heads-Up-Outlaw

I looked at that file, but there really isn't any useful info for what we're after here unfortunately. Have your tranny guy look at it and I'm sure he'll know what to do.

As far as that code, honestly I'm not familiar with it as I haven't seen too many 4x4 trucks in a long while now. But, if necessary I'll get my mind around it for ya!

g