07 Allison Problem

[rsaint]

Got a 07 GMC Classic diesel started it up to move to plow snow and went backwards and stopped shift inhibit came on had to let it warm right up then it moved fine, is it time to get the wallet out or dump it.

 

[tater]

I got 09 does same thing sometimes. Was told its tranny fluid getting to cold/heavy that it trips a sensor. Only gives me 4th gear. No reverse. Warm up for while and goes away... Or buy programmer.. Clear the code and giver.

 

[bigz64]

cold allison trannys are supposed to stay in a low gear to warm then truck up faster, says so in the owners manual. not to sure about the no reverse thing

 

[rsaint]

I got 09 does same thing sometimes. Was told its tranny fluid getting to cold/heavy that it trips a sensor. Only gives me 4th gear. No reverse. Warm up for while and goes away... Or buy programmer.. Clear the code and giver.

Have the EFI live may have to contact Mitch on that. Backed up and no go forward and only 2c outside not cold but sat all night.

 

[markaug]

How's the fluid level? Any DTC's set?

 

[teeroy]

mine gives me the shift inhibit message if I shift into gear at too high of an rpm, usually when rocking back and forth trying to get unstuck. it has done the no reverse/stuck in 4th thing to me before too, both times it was -35 or colder. warmed up and went away.

 

[tater]

Mine has also only done when -25 to -35 and sits for couple days...

 

[1100]

I've never had this problem with my 06. When its cold outside, you are suppose to put the trucks in neutral to warm up. Suppose to circulate oil better.I do it after -20 and have never had a problem. My dads 07 was doing the shift inhibited thing, when cold out. The oil was just on the low side of halfway on dipstick. According to GM if not up to the full line the oil sucks down when cold and trips the sensor. He has sunset kept his right on full dipstick mark and hasn't had problems since.

 

[rsaint]

How's the fluid level? Any DTC's set?

The level is within the marks maybe put some in and see???

 

[KawisakiRider]

Same story with me when it was -30, but I was stuck in 5th with no reverse, fluid was in between the lines but on the low side, topped it up an good to go.

 

[Marley]

I have had a problem with the park-neutral position switch on the transmission. Have changed it twice.

It is a little box-of-tricks attached to the drivers side of the transmission that sends the signal to lock the doors etc when you shift in gear.

If you drive in a lot of dirty slush then water gets forced inside the unit and you get all sorts of weird stuff happen including the shift range inhibit problem.

Easy to replace but costs almost $300 IIRC

 

[Summitric]

The prndl (park-neutral switch) is pretty common. I would recomend getting the newest/latest/updated transmission reflash at your local gm dealer....... Update cures the "no reverse" problem i believe.

 

[bigz64]

I've never had this problem with my 06. When its cold outside, you are suppose to put the trucks in neutral to warm up. Suppose to circulate oil better.I do it after -20 and have never had a problem. My dads 07 was doing the shift inhibited thing, when cold out. The oil was just on the low side of halfway on dipstick. According to GM if not up to the full line the oil sucks down when cold and trips the sensor. He has sunset kept his right on full dipstick mark and hasn't had problems since.

i believe that is olnly for the 5 speed allisons, so early 06 and earlier. something to do with fluid not being circulated when in park.

the 6 speeds dont have that issue

 

[1100]

Mine is a late model 06, with the six speed. To think I've spent this much unneeded time walking in the cold. Lol. Good exercise I guess.

 

[Summitric]

also does the fluid smell burnt?? maybe time for a trans flush and a new "spin on" trans oil filter??

 

[tater]

The no reverse isn't a problem... It's limp mode and designed to let least amount of torque through.. That's why no reverse or 1,2,3 gears. And mine is 09 6 speed. My 05 never had problem.

 

[senorjeem]

I can tell you that you don't want a problem. I smoked the tranny in my dirtymax and a reconditioned replacement was $5200.00

 

[tater]

Ouch. How did you do that?? I drive mine like I stole it and always have... No problems.. Other than cold issue.

 

[rsaint]

also does the fluid smell burnt?? maybe time for a trans flush and a new "spin on" trans oil filter??

Dosent smell burned at all got 200,000 on it never changed filter never new there was 1 till now.

 

[Summitric]

dosent smell burned at all got 200,000 on it never changed filter never new there was 1 till now.

i would get the fluid flushed, then, and replace that spin-on tranny filter........ Problem might be solved