GM/Detroit 6.5L ENGINE CONTROLS – DTC U1192 Loss of VTD (Passlock)/EVO Communication

Circuit Description
The PCM monitors the serial data (class II) circuit for communications from the Passlock/EVO controller. If the Passlock/EVO controller is not communicating with the PCM this DTC will set.

Conditions’for Setting the DTC
No serial data (class II) from Passlock/EVO controller to the PCM.

Action Taken When the DTC Sets
This DTC will not illuminate the MIL.

Conditions for Clearing the MIL/DTC
• A History DTC will clear after 40 consecutive warm up cycles with no failures of any non-emissions related diagnostic test.
• PCM battery voltage is interrupted.
• Use of a scan tool.

Diagnostic Aids
This DTC will not set unless the PCM and ATC controllers have already establish communications first. This DTC will only diagnosis an open or intermittent connection from the Passlock/EVO controller to the splice.
The PCM enables fuel (scan tool display PCM in VTD Fail Enable YES) on this and future ignition cycles only if the failure occurred when the engine was running.

Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
1. In this step, the Powertrain OBD System Check is being performed.


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