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2003 chevy trailblazer_lt
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11 Posts
Discussion Starter · #1 ·
I just inherited my moms 2003 TB with the I6 and during times on the freeway when I have had to give it the gas, and it down shifts, it wont shift back to high gear unless I let completely out of it. And sometimes it still takes a few seconds to do it.

Thoughts?
 

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2003 gmc envoy_slt
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7,190 Posts
How many miles since the fluid was changed last? Have you checked the fluid level? Does it smell burnt? Does the fluid look clear on the dip stick? When you let off the gas the trans does not shift very fast. At least mine doesn't.
 

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2005 chevy trailblazer_ls
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343 Posts
Mine does the same thing at 36k. I didn't notice it until I put in my PCMforLESS tuned PCM and it seemed like the transmission would downshift even with the slightest press of the gas pedal, and to get it to upshift I had to get out of the gas completely and then put my foot back down after it shifted. I put my original PCM back in and it did the same thing. I guess I just didn't notice it before.

After I got to my destination I took it straight to a dealership and had them check it out. The CEL was for the torque converter so they checked that first and it was fine. They went through the valve body and didn't find anything there either. They said fluid looked great but replaced it and the filter. When I picked it up the tech said that if it happens again then they TC is probably toast and would need to be replaced.

I'm at 39k now and the light hasn't come on again, but the transmission is still pretty touchy. I'm wondering if it has to do with the speed sensor reading low because of my larger tires and the TCM thinks that the speed is low for the engine RPM reading, so it downshifts to try to get the speed to where it should be for the RPM? Just my theory...
 

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2003 chevy trailblazer_lt
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11 Posts
Discussion Starter · #4 ·
How many miles since the fluid was changed last? Have you checked the fluid level? Does it smell burnt? Does the fluid look clear on the dip stick? When you let off the gas the trans does not shift very fast. At least mine doesn't.
My parents bought it with 71k on it, it now has 81k. My mon had the fluid changed last October at the dealership.
 
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