It could be a case of a failed speed sensor causing both issues. The speedometer has a speed sensor on the transmission and there is also a pulse generator, both of those are used to determine shift points and to drive the speedometer itself. There are a couple things to try to see what the issue is, one would be to shift the transmission manually. So, you would start out in 1 then get up to say 1,500 RPMs, now shift to 2, RPM should drop, and you should feel it shift, now speed up some and shift into D you should feel it shift again. Now get up to speed and see if you feel it gently drop some rpm as the transmission locks the torque converter up. Or the better way would be to use a scan tool that can show live data and show you which gear the transmission is in, and it would show you if the speed sensor was bad because it would also show you speed. If the transmission seems to shift okay manually but doesn't when you put it straight into drive (should feel the same shifts) then it's likely the speed sensor. If it seems to shift okay but no speed and the speed does show on a scan tool, then it's probably the speedometer drive motor itself.
Not hard to change the cluster but you want to test the other items first. No reason to replace the cluster if the sensor is at fault.
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Tuesday, July 25th, 2023 AT 7:45 PM
