So I removed the battery power and then powered backup. Problem remains. Works fine in drive but when I shift to manual the shifter indication does not change, still shows its in drive. It does go down a gear and stays there but cannot manually shift.

Have an appointment with a GM dealer. Called GM tech line again to ask for a answer on the extra shift detent, no answer yet. Also asked for warranty as I have just 600 miles on it but just over the 2 years. It is always tough building a vehicle under 2 years as you generally buy your drivetrain to fit first and then build the rest. My buddies that bought the same engine and trans packages about the same time I did do not have their projects completed yet. But they both have the extra shifter position that I have.

Had my appointment with a Pacific GM dealer today. They treated me very well. Spent a couple hours testing to checkout the P18C2 code which is "internal mode switch". Next step is taking the pan off so we have ordered a mode switch in case that ends up being the problem. Still have not heard back from GM on warranty or extra shift detent.

I finally got a email from GM telling me there are 5 detents used and 6th is not. Not really any help as I and 2 others I know of have 6 detents. When shifted from M to the 6th detent I get "error" displayed.

Any improvements in drivability with the things you tried?

Is the extra detent the only issue you still have?


Jeff-

Don't know if the extra detent is an issue or not. The issue I do have is no manual operation but hopefully get that fixed tomorrow with "internal mode switch". Other than that transmission is fine.

Took to the GM dealer and they changed the internal mode switch. During final testing the same code came back. It appears that when we plug the Dakota Digital BIM module into the OBD2 port it causes the code. Dakota's engineers on it now and I have no doubt they will come up with a fix. The high tech modern age we live in. Another thing to complicate things is the code P18C2 is now a "permanent" code. Yes its a thing. Google it.

I have had similar issues related to the BIM. You can go into the BIM settings and change the bus address of the BIM. I’ve solved a couple of strange issues changing the address. There is four address options if I remember right.

Having the BIM and a scanner connected at the same time can also cause some strange things to happen depending on the style of Y connector you use on the port.

Don

Thx for that. I went to GM dealer today and had them reset the code several times. Funny thing is the GM scanner says the code is gone but my HP tuners says its still there?? Questioning if its the BIM as I had GM reset and then drove around without the BIM plugged in and Code came back. Being a "permanent" code not sure which scanner to believe. All the GM tech had heard of are soft and hard codes. Just looked at my BIM-01-02 manual says normally it does not use Bus Id's as other BIMs do.
So this code P18C2 is the code that had us change the Internal mode switch. GM tech noticed manual didn't work when all back together after he reset, and I guess assumed the BIM cause it was the last thing plugged in. My HP tuners scanner always says the code is there even right after GM tech reset. Now I was assuming the GM scan tool was super duper and could reset permanent codes. Never assume. If you look up Permanent OBD2 codes they tell you they are relatively new and after the repair the vehicle ecu will keep the code active but not light the check engine lamp until it decides the repair is good after a certain number of cycles.

I am not talking about codes. I am talking about the BIM bus address. The instructions to change it are in the BIM instructions. There are four options. Try all four and see if the issue goes away. The permanent code will probably not clear, that is something different.

Don