GM/Detroit 6.5L ENGINE CONTROLS – DTC P1630 Theft Deterrent PCM in Learn Mode

C ircuit Description
This diagnostic test checks for the Enable Password Learning Flag indicating the PCM is in learn password mode. This mode allows the PCM to learn the password from the Passlock module at assembly or when being serviced. The password needs to be learned whenever the PCM or the Passlock module is replaced,

Conditions for Running the DTC
The igni tion switch in the ON position.

Conditions for Setting the DTC
When the Enable Learning Flag is set.

Action Taken When the DTC Sets
The malfunction indicator lamp (MIL) will not illuminate.

Conditions for Clearing the DTC
• A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any fai lures
• The use of a scan tool.

Diagnostic Aids
The PCM in learn mode is a DTC for the vehicle at the assembly plant, dealership and outside garage personnel as an indication that the learn mode is enabled. This means the PCM is now ready to learn a new password. Refer to Vehicle Theft Deterrent system for further diagnosis.


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