M6 TR6060 Multiple Incorrect Gear Ratio Codes
 

I originally had a P0735 code come up weeks ago, which is now a permanent code. Since then I changed the transmission fluid to Royal Purple and it is shifting great, but now I have multiple Incorrect gear ratios codes for 1st, 2nd, 3rd, 5th and 6th gears. Has anyone ever experienced this? I think this is super strange considering it's a Manual Transmission.

Did you ever check the reluctor on the output shaft for tightness? That is used by the speed sensor and is a known issue (although rare) with 2016-2017 manual cars.

Never got a chance to, but hopefully this weekend I can get the car in the air and check it out. I just feel it's so weird that it's now throwing codes in almost every gear except 4th.

Is the gear indicator accurately reporting the correct gear, even though it is saying the ratio is incorrect? The ratio error is based on a calculation, but if it thinks it's in a different gear it may be an indicator problem.

I never thought about checking that, I will definitely see if it is correct, what would cause it not to report the correct gear?

I think the sensor can go bad, or maybe the wiring to the sensor. The part looks like an easy external bolt-on. Now whether it is easy to get to...
https://tnpowertrain.com/products/20...ensor-24283437
Edit: Note in that photo in the link the number stamped on the part is different than the part number they give. I would bet this part is standard across all models.

Thank you for the link, I appreciate it. Im going to look into where this sensor is located

According to the repair manual it is rear left at the top. Speed sensor is rear right, below the backup lamp switch.

I can't find a picture which shows the location. But searching for GM part 24283437 shows it is actually an assembly with the sensor mounted to an aluminum plate. May help in locating this:
https://caryparts.hendrickcars.com/o...ensor-24283437

Update: picture makes it look like it is rear right:

Awesome ! Thank you!

So my car is at the chevy dealer now, they ran a bunch of test and found that the shifter fork that sits on top of the transmission is bad, and when shifting is causing the light to come on. Hopefully I should get it back in a few days

Well, for what it's worth, I would love to see a picture of any bits of the shift linkage. I thought all the sensor bits were in the tranny itself, and that's what the repair manual seems to show. My repair manual doesn't give much detail on the actual shifter.
So, I thought the shifter was a "dumb" unit and would be OK as long as it gets you through the gates.
Hope they get it straightened out.
Speaking of straightened out... maybe the fork that links to the tranny got bent and you are only getting halfway into gears???

Thank you, yea Im curious to see how bad the fork is, but when I was shifting, I didn't have any issues getting each gear into the gates.

So it turned out to be a faulty magnetic sensor that is attached to the shifter fork, they tested it and it was bad, got the car back and all is good now

Don't see a magnet here. And no electrical connections to the shifter itself.

There is at least one good photo of the underside in this listing. Ebay is often better than GM parts sites for photos.
https://www.ebay.com/itm/26474747849...3ABFBMoK2e9Mhj