VTD UART Communications Involvement

VTD UART COMMUNICATIONS
The Passlock System requires the Powertrain Control Module (PCM) and the Electronic Instrument Panel Cluster (IPC) to communicate various functions in order to operate. These functions are transmitted over the UART Serial Data Line, or CKT 800. For an explanation of UART operation, refer to Instrument Panel.

The TECH 1 Scan Tool can be used to monitor the communications between the IPC and the PCM. This is called SDL (Serial Data Link) on the TECH 1. Refer to TABLE #1 for a listing of Vehicle Theft Deterrent Function Descriptions.

VTD MODING
The VTD Moding Function is SET once a theft decision has been made by the IPC.

REVERSE ROTATE
The Reverse Rotate Function tells the Powertrain Control Module when to make it's theft decision. If the function's status is ACTIVE, the IPC has determined that the ignition key is in the START position; otherwise the function should read "INACTIVE." Please note, the PCM has the capability to make it's own theft decision independent of this function under certain circumstances.

VTD PASSWORD
The VTD Password function tells whether or not the IPC has sent the correct coded password to the PCM. If the IPC has read any R-CODE, it will send this password. This function will then read as RECEIVE. This means the IPC has received the Passlock Lock Cylinder's R-CODE. If the IPC could not read an R-CODE, for any reason, this function will read as NOT RECEIVE.

VTD ACKNOWLEDGE
The Powertrain Control Module outputs the VTD Acknowledge function if PASS-THEFT condition is present for this ignition cycle.

VTD TAMPER
The Powertrain Control Module outputs the VTD Tamper function if it has determined a FAILED-THEFT condition for this ignition cycle. Note, this function may also set if the IPC has determined a failed-theft condition.

REFERENCE SYNC
The Reference Sync Function tells the IPC if the engine is physically cranking.

VTD OPTION
The VTD Option Function tells if the IPC has ever detected the presense of a Passlock Lock Cylinder. Once this has occurred, the IPC will set this function to YES.

CRANKLOW
The CRANKLOW Function reads as ACTIVE when the Ignition Switch is in the START position. Otherwise, this function will read as INACTIVE.

FOR COMPONENT LOCATIONS, REFER TO Diagrams.