Was just wondering if anyone else besides me, has had to have their tranny reprogramed for the second time due to tranny leaks in cold weather? I had mine done again the other day and now not only does it feel like I have a significant loss of power, the tranny shifts very erratically, also now it seems to be getting around 12 mpg where it use to get about 15 to 16. Would be curious to know what they are doing by reprograming to stop the leak. I Tow a 16k trailer in the hills of Alaska and don't want to loose a tranny. has 16,000 miles and has already been in the shop 7 times.

Where was it leaking? If it's out the breather near the back of the tranny then there is a modification to the dipstick tube to make it breath better. Mine did it last winter and then again this winter. So far since the dipstick mod the leak stopped.

Was just wondering if anyone else besides me, has had to have their tranny reprogramed for the second time due to tranny leaks in cold weather? I had mine done again the other day and now not only does it feel like I have a significant loss of power, the tranny shifts very erratically, also now it seems to be getting around 12 mpg where it use to get about 15 to 16. Would be curious to know what they are doing by reprograming to stop the leak. I Tow a 16k trailer in the hills of Alaska and don't want to loose a tranny. has 16,000 miles and has already been in the shop 7 times.

i'm with you on that one, i can't see where reprogramming has anything to do with a leak:eek:. i'd take it to another shop if i were you:D

I have not heard of a reprogram to fix a leak, sounds more like a vent problem if it only happens on cold start? Your trans is shifting poorly because after a reprogram it has to re-learn all of the shift adaptives The shifting should get better within a few hundred miles

The leak has been coming out of the coolant lines and also out of the vent. It looked like it was coming out of the transfercase. The first time I took it in for this they reprogrammed tcm as per gm instructions. This time they found bulletin pertaining to fluid coming out of vent and reprogramed again. This dealer is the only dealer with in 300 miles of me and I have a 1000 miles sense reprogram and the power and shifting hasn't improved. On the bright side the leaks are gone.

Moved to Allison OEM...

The only reprogram that I recall for the tranny was last winter when they were burning out torque converters under high idle and the temp was lower then -30C. the cooler lines are common to leak in the cold, there's the mod to the dip stick which will stop the fluid coming out of the breather, and I think some guys said the input or output of the transfer case has leaked. None of these should have needed a reprogram other then the issue last winter. I'd take it back in.

Thanks for the input, I'll be taking it back as soon as I get the chance. The dealer is 80 miles from here. I tried to talk to the dealer later after I picked it up but the shop was so busy he said he just wanted to quit, so he wasn't interested in listening to me. Temps that day were running about -20 to -30. The receipt they gave me states that they found a new TSB and reprogrammed per bulletin. All the leaks are fine for now being as our cold snap headed South towards some of you.

Two separate issues, one single cause. Dexron6 gels in the trans aux cooler and doesn't flow in extreme cold temps. That's why Allison recommends TranSynd.

As far as cooler line leaks, they're redoing the crimps on the lines to keep them from leaking. There is a TSB out dated Dec. 12, 2008. Another set part numbers is due out any time.

The TCM reprogram is to keep the trans warmup mode from overheating the torque converter due to the lack of flow. The second cal pushes the temp where it assumes the cooler is blocked by a few degrees and shortens the on time for the cycle. It shouldn't give you any other performance issues.

Thanks Crafty1. That completely answered my question. ;) I'll look into fuel for performance and mpg. shifting still not right, but could be because loss of power.