Serial Link Ext Failure Code When Sending Secret Key to PCM

NAME OF CODE
Serial Link External Failure

WHEN MONITORED
At ignition On, after ignition ON during any rolling code handshake that occurs with the PCM due to a SKIM reset or a PCM reset, or during "Secret Key" transfers to the PCM.

SET CONDITION
This condition is set when the SKIM does not receive an expected bus message transmission acknowledgment from the PCM after 3 transmit attempts.

THEORY OF OPERATION
The SKIM monitors the data bus for PCM bus message acknowledgments.

POSSIBLE CAUSES
- PCI bus wire in the wiring harness is open
- PCI bus wire in the wiring harness is shorted to ground
- PCI bus wire in the wiring harness is shorted to battery voltage
- Defective Sentry Key Immobilizer Module
- Defective Powertrain Control Module