1989 BMW 750Li Service engine light

The service interval can be reset with a resetting tool from Peake research or a reasonable facsimile. If the radio shows "code" in the display, you are ready to enter the code. The radio code, if incorrectly entered, will require the radio to be left on for 30 minutes to reset. You can then retry your code, there is a "three strikes" so if it doesn't work the first time, check your code, make sure you enter the digits correctly.

I just don't know what buttons to push to enter the code, nothing showed on the screen when I tried it just beeped a few times after I pushed some buttons.

The preset button numbered one through six is where you enter the code. Leave it on for at least 30 mins to clear the lockout, then reenter the code.

Thanks much.