'06 Tra ilblazer forgets to downshift

RayP(MI) · Apr 15, 2012

Not very often, just once in a while, come to a stop, and try to accelerate, and nothing - stuck in a higher gear. When it first started happening, it threw a 1/2 transmission solonoid code. Monkeyed with it a while, and finally replaced the solonoid, along with 7 quarts of Dextron SIX! (NOT CHEAP!). Solved the problem somewhat.

Now, once in a while, it still fails to downshift, no codes, no nuttin"! Can always override with the gearshift lever, manually downshift. Just talked with my electrical auto technician - he runs an auto-electric shop in another part of the state. He thinks computer needs to be flashed. (Something he recently got the equipment to do. - that"s a whole "nother story.)

Anyone else run into this? What did you do? Did it do any good?

David G · Apr 15, 2012

How many miles, have you ever flushed it?

RayP(MI) · Apr 15, 2012

120 thousand - ended up changing fluid by default when I changed solonoid.

Allan in NE · Apr 15, 2012

I think you're dealing with mechanically failing force motor.........yeah, another 7 quarts too.
:>(

Allan

greygoat · Apr 15, 2012

Dunb Question: You did change the filter when
you changed the fluid...didn"t you?
(New fluid could loosten some debris)

RayP(MI) · Apr 15, 2012

Yeah, takes deep filter, guess how I know.

Anonymous-0 · Apr 15, 2012

I had an 06 trailblazer the electronics on them are junk and GM knows it. Traded for a 2010 toyota 4 runner never going back to GM again.

BrianJasper co. Ia · Apr 15, 2012

What do you mean "it forgets to downshift"? You mean when you come to a stop then go to take off and it isn't in low gear? I'd want to verify the commanded gear, make sure the trans isn't losing 12V to the solenoids, (they default to 2nd gear if they do). Shift solenoids only control balance fluid pressure. There is a spool valve under each one that moves. That moving valve is what actually changes the trans gear. You can go in and see if the valve moves freely. Reman valve body is probably what you need.

Anonymous-0 · Apr 15, 2012

Is it idling slow, the throttle bodies had an issue with this. Watch the volt gauge, if the transmission needs 12 volt on the solenoid it might not be getting it. Rev it up 200 RPM at the next stop and see if it shifts.

Sprint 6 · Apr 15, 2012

Your friend is probably right, the PCM needs to be reflashed. Some trucks, in the right random condition, would try to take off in second gear. This was more common on the Tahoe, but could affect the Tblazer. Have a dealer check it before you go replacing parts.

Allan in NE · Apr 16, 2012

Hmmmm, dunno.

A pcm issue would not be intermittent.

Also, if it was going into default (2nd gear), it would leave a track.

Only two things that can make it fail to down shift; a mechanically failing force motor (an electrical issue which would, again, leave a code) OR a intermittant total loss of power, which would place the transmission in 3rd.

He can manually override and wake the darlin' up, therefore I still say he should look at the motor. They have a history.

Allan

'06 Tra ilblazer forgets to downshift

RayP(MI)

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David G

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RayP(MI)

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Allan in NE

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greygoat

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RayP(MI)

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Anonymous-0

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BrianJasper co. Ia

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Anonymous-0

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Sprint 6

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Allan in NE

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