Speedometer and Shifting Problem?

2008 CHEVROLET TRAILBLAZER

225,000 MILES • 4.2L • 6 CYL • 2WD • AUTOMATIC

ELFORBO1987

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Hello, my dad's 2008 I6 Trailblazer RwD Automatic just had the transmission rebuilt a month or two ago and now it's having issues. The speedometer isn't working, and he said it's shifting rough or not shifting into higher gear.

We replaced the transmission speed sensor because it was the easiest and cheapest to start with. Didn't work. We checked fuses and they're all good.

What other sensors might there be? Is there an internal one for this transmission? Could it be a wheel speed sensor? All other gauges on dash are working fine.

Thanks in advance!

Sep 22, 2023 at 9:09 AM

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JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

If you replaced the speed sensor, then either we have a wiring issue or the cluster itself is faulty.

If you look below, I attached the diagnostics related to a non-functional speedometer. Take a look through them and let me know if you are comfortable performing them.

Take care and let me know.

Joe

See pics below.

Images (Click to enlarge)

Sep 22, 2023 at 1:45 PM