Bob is right but, it does not only apply to the TCM and ECM, it applies to any module on the BUS which include the ABS and BCM modules. The VP also has its own module.1693... ... ... ... . even after all these years it is still the simplest and yet most misunderstood code. It simply means you are looking in the wrong module!The companion module is where you need to look. If you are looking in the ecm and get it look in the pcm to pull the code that matters and vice versa.
Bob