Transmission Problems

[TheLawnRanger]

My 2012 Colorado is having automatic transmission problems. I'm planning on taking it to my local shop tomorrow. It will only go into third gear and drive if I start in first gear and go progressively through the gears until I get to third and then drive. The truck functions fine until I slow down to a near stop or stop. I don't know a lot about transmissions and would like to have an idea of what's wrong so I don't get taken to the cleaners for nothing.

 

[Furious]

If you have to worry about being taken to the cleaners for nothing with this shop you intend to go to then you need to find a different reputable shop that specializes in transmissions.

 

[el Nuke]

My 2012 Colorado is having automatic transmission problems. I'm planning on taking it to my local shop tomorrow. It will only go into third gear and drive if I start in first gear and go progressively through the gears until I get to third and then drive. The truck functions fine until I slow down to a near stop or stop. I don't know a lot about transmissions and would like to have an idea of what's wrong so I don't get taken to the cleaners for nothing.

Miles?

 

[TheLawnRanger]

170,000 miles

 

[el Nuke]

170,000 miles

Has the transmission fluid and filter been serviced at any point in those miles?

If not, the trans is likely toast and will need a rebuild or to be replaced.

If the service history is unknown, a safe assumption is the trans is toast and will need a rebuild or to be replaced.

 

[Lubener]

Any codes?

 

[TheLawnRanger]

No codes.

 

[Lubener]

No codes.

Looks like an overhaul is in your future.

 

[clinebarger]

My 2012 Colorado is having automatic transmission problems. I'm planning on taking it to my local shop tomorrow. It will only go into third gear and drive if I start in first gear and go progressively through the gears until I get to third and then drive. The truck functions fine until I slow down to a near stop or stop. I don't know a lot about transmissions and would like to have an idea of what's wrong so I don't get taken to the cleaners for nothing.

It won't move unless you place the shifter in 1st?.....If that's the case....The Forward Sprag is likely broken or the Forward Clutches are completely smoked.
If this happened all the sudden.....My money is on the Forward Sprag. Usually takes quite a shock load to break a factory SKF sprag.

When you place the shifter in L1 or D2.....The Overrun Clutch comes on which will effectively bypass the Forward Sprag & Forward Clutch, Then when you build enough speed, The shifter in D3 & the Commanded ratio is 3rd.....The Overrun Clutch stays on.
In 4th.....The Sprag is Overran & not needed to power the unit.

There are only 2 Overrun Frictions & they won't last long manually shifting the unit.

 

[TheLawnRanger]

It won't move unless you place the shifter in 1st?.....If that's the case....The Forward Sprag is likely broken or the Forward Clutches are completely smoked.
If this happened all the sudden.....My money is on the Forward Sprag. Usually takes quite a shock load to break a factory SKF sprag.

When you place the shifter in L1 or D2.....The Overrun Clutch comes on which will effectively bypass the Forward Sprag & Forward Clutch, Then when you build enough speed, The shifter in D3 & the Commanded ratio is 3rd.....The Overrun Clutch stays on.
In 4th.....The Sprag is Overran & not needed to power the unit.

There are only 2 Overrun Frictions & they won't last long manually shifting the unit.

That sounds like I'm about to be a few thousand dollars lighter.

 

[clinebarger]

That sounds like I'm about to be a few thousand dollars lighter.

Bring it to Fort Worth & I'll put a good Used sprag carrier assembly with a New Borg Warner Sprag, Converter & Output Seals, Valve Body gaskets. Pan Gasket, Filter & fresh ATF for $1800. This will be a PATCH, Not a rebuild!! A full rebuild with a 3 year warranty runs $3500