DTC P1630: Powertrain Control Module In Password Relearn: Description
WARNING: This page is about a different car, the 2001 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
Vehicle Theft Deterrent (VTD) system is incorporated within Instrument Panel Cluster (IPC). If IPC has been replaced, password must be relearned. If Powertrain Control Module (PCM) is replaced, new PCM should learn password within a few seconds after ignition switch is turned to RUN position. This is an information code indicating PCM is ready to learn VTD password. DTC will be stored when PCM remains in theft deterrent password learn mode for 2 seconds or more. PCM will not illuminate Malfunction Indicator Light (MIL). PCM will store conditions which exist when DTC is stored as failure records data only. This information will not be stored in freeze frame data.