While driving at a constant speed the car pulses?

2012 BUICK ENCLAVE
152,000 MILES • 2WD • AUTOMATIC
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ANNA CUMMINS
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It feels like the transmission is slipping, but I recently had it rebuilt. the tachometer does move slightly when it does this. It does not do this when accelerating or coasting, just when going as a constant speed.
Car has been serviced regularly.
Dec 13, 2022 at 8:28 PM
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STRAILER
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It sounds like the input shaft speed sensor inside the transmission is not working correctly. We should run the codes though to see what comes up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is the location of the sensor so you can see what I am talking about. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.
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Dec 15, 2022 at 11:25 AM