Allison Tc Not Locking Up

DENTGUYS · January 4, 2010

2001 8.1 allison 4x4 . will lock up in t-h mode. 85000 miles . oil smells.

vettelovralexand · January 5, 2010

2001 8.1 allison 4x4 . will lock up in t-h mode. 85000 miles . oil smells.

Just out of curiosity how do you know it isn't locking up? Tech 2 or just don't feel it? Also, only in Tow/Haul? The reason I say this is that you may just not notice it because it locks down in 2nd gear instead of 3rd or 4th like usual and probably feels a lot more like an actual "shift" than what it usually does.

Shaners · January 5, 2010

Is it cold outside?

DENTGUYS · January 5, 2010

it is about 50 out side. we went for a drive in the hills and the trans temp got to about 220.the eng temp was 185. then put in to t-h and the trans temp dropped 185. shut of t-h and it wnet back up. not hauling anything. mpg has dropped from 11 to 8 in town. freeway i was getting about 15 now 12 . t-h i get 15 on freeway. thanks for reading.

DENTGUYS · January 18, 2010

HELP

RJG183SA · January 18, 2010

2001 8.1 allison 4x4 . will lock up in t-h mode. 85000 miles . oil smells.

I suggest you bring it to a GM dealer or reputable trans. shop to properly diagnose the problem. Then go from there.

Rat4go · January 20, 2010

The computer controls the torque converter. If it's locking up in TH but not in regular mode, it's likely not the trans unless the converter is mostly toasted and using TH adds extra pressure that makes the toasted converter actually apply. Dealer can put scan tool on to see slip at the converter AND to see if it's being commanded by the computer. If the command is there, but it's slipping....well, that's not so good. Stinky fluid doesn't sound good either. Is it still reddish, or dark like used motor oil?

DENTGUYS · January 21, 2010

Had trans flushed about 12,000 miles ago. no metal of clutch flackes. dealer siad that the fluid looked great . this looks and smells the same as it did 12,000 miles ago. The dealer could not find anything wrong then but. I feel there is some thing wrong. This is not my first rodeo. But they must know right.

donniecfd32 · March 7, 2010

I had this problem last summer. I finally took it to my Buds trans shop. He hooked it upm to his mac daddy anilizer and it showed that the crank sensor was bad. I replaced the crank sensor and the problem was corrected.