has anyone complained about the limit of characters allowed in the subject line? we should be allowed to use more than 50 characters.
2006 gmc sierra 2500hd, 8.1L gas engine with allison 1000 6-speed automatic transmission. truck drives fine never a problem until now...
cold morning that is around 5°F (-15°C) this has happened twice now.
I start the truck and usually let it idle for a minute before shifting into drive, by then engine rpm has come down from 1000 to 800 rpm. when truck is hot then idle is 600 rpm.
Putting the shifter into D, the trans engages and i start moving forward then within 5-10 feet i lose power to the wheels like I had shifted into neutral. when this happens if i'm on the gas or give it gas, the engine will rev up to 1500 rpm like it was in neutral. there is no noise and everything sounds/feels fine except i'm not moving.
The first time this happened less than a week ago, for about 10 seconds i kept giving it gas and engine rev'd to 1500 with no power to wheels, I then put in neutral and rolled backward the 10 feet i had gone, back to flat spot on driveway, and put it in park. my driveway is about 40 feet going up hill and steep about 30° however i had not hit the steep part when problem happened, just enough to allow me to roll backwards.
Once in park, I noticed the DIC display (i think it's called) that tells odometer, trip, fuel economy stuff say something about transmission shifting problem, but i forget the words. I shut truck off, waited 5 seconds, restarted, idled for 20 seconds, then left normally getting up driveway no problem. This morning, put in drive and after about 2 seconds going 10 feet i lost power to rear wheels while still on the flat spot of driveway (so pretty sure angle of truck not a factor) this time i noticed the yellow light under the D in PRNDM1 I think blinked then it went out. I shifted to park, and within a couple seconds the yellow light reappeared under P, and this time i did not get any warning in the DIC display. I let it idle for 30 seconds in park, did not shut engine off, held rpm's at 1500 for a little bit, everything sounds/feels fine. shift to drive and leave no problem. This is at 8am truck sitting outside all night, review mirror says outside temp is 5°F which was correct. what would cause this?
i bought truck few years ago having 75k miles, now has 95k miles. within the first year of having it around 80k miles i had dropped pan and replaced the filter in there, along with the external spin on, and refilled with napa brand dex6 atf. old atf looked, smelled, felt fine. transmission has never shown signs of leaks, and last i checked atf level was in acceptable range. and within last year around 90k miles i replaced the spin on filter. When i did that initial trans service dropping pan i put the transgo jr kit in that's recommended for the 2006 allison 6-speed, never found anybody say bad things about that other than it does next to nothing the only thing it really does is raise line pressure some X psi which is insignificant in the grand scheme of things. however what i did notice and i'm not sure if caused by transgo jr kit was after installing it on cold mornings (less than 40°F) first time shift into drive it would be harsh and forceful engagement if shifted into drive not long after start. but say if i drove 10 feet, shifted to park, then back into drive the engagement was normal like it would be any other time above 40°F. Or if i let the truck idle for 10-15 minutes then it would not shift into gear harsh.
hope that's enough info, i'm pretty sure the main cause is the extreme cold weather but would like to know why.
2006 gmc sierra 2500hd, 8.1L gas engine with allison 1000 6-speed automatic transmission. truck drives fine never a problem until now...
cold morning that is around 5°F (-15°C) this has happened twice now.
I start the truck and usually let it idle for a minute before shifting into drive, by then engine rpm has come down from 1000 to 800 rpm. when truck is hot then idle is 600 rpm.
Putting the shifter into D, the trans engages and i start moving forward then within 5-10 feet i lose power to the wheels like I had shifted into neutral. when this happens if i'm on the gas or give it gas, the engine will rev up to 1500 rpm like it was in neutral. there is no noise and everything sounds/feels fine except i'm not moving.
The first time this happened less than a week ago, for about 10 seconds i kept giving it gas and engine rev'd to 1500 with no power to wheels, I then put in neutral and rolled backward the 10 feet i had gone, back to flat spot on driveway, and put it in park. my driveway is about 40 feet going up hill and steep about 30° however i had not hit the steep part when problem happened, just enough to allow me to roll backwards.
Once in park, I noticed the DIC display (i think it's called) that tells odometer, trip, fuel economy stuff say something about transmission shifting problem, but i forget the words. I shut truck off, waited 5 seconds, restarted, idled for 20 seconds, then left normally getting up driveway no problem. This morning, put in drive and after about 2 seconds going 10 feet i lost power to rear wheels while still on the flat spot of driveway (so pretty sure angle of truck not a factor) this time i noticed the yellow light under the D in PRNDM1 I think blinked then it went out. I shifted to park, and within a couple seconds the yellow light reappeared under P, and this time i did not get any warning in the DIC display. I let it idle for 30 seconds in park, did not shut engine off, held rpm's at 1500 for a little bit, everything sounds/feels fine. shift to drive and leave no problem. This is at 8am truck sitting outside all night, review mirror says outside temp is 5°F which was correct. what would cause this?
i bought truck few years ago having 75k miles, now has 95k miles. within the first year of having it around 80k miles i had dropped pan and replaced the filter in there, along with the external spin on, and refilled with napa brand dex6 atf. old atf looked, smelled, felt fine. transmission has never shown signs of leaks, and last i checked atf level was in acceptable range. and within last year around 90k miles i replaced the spin on filter. When i did that initial trans service dropping pan i put the transgo jr kit in that's recommended for the 2006 allison 6-speed, never found anybody say bad things about that other than it does next to nothing the only thing it really does is raise line pressure some X psi which is insignificant in the grand scheme of things. however what i did notice and i'm not sure if caused by transgo jr kit was after installing it on cold mornings (less than 40°F) first time shift into drive it would be harsh and forceful engagement if shifted into drive not long after start. but say if i drove 10 feet, shifted to park, then back into drive the engagement was normal like it would be any other time above 40°F. Or if i let the truck idle for 10-15 minutes then it would not shift into gear harsh.
hope that's enough info, i'm pretty sure the main cause is the extreme cold weather but would like to know why.
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