P1666

DTC P1666
Anti-Theft Alarm serial link fault Drive cycle A:Signal implausible.

Possible causes by suggested order of priority:
^ Open circuit - C637/33 (LGS) to C661/10 (LGS).
^ Connectors C661, ECM C637 (B).
^ Alarm ECU Faulty.
^ Alarm ECU not fitted.

Open Circuit - C637/33 (LGS) to C661/10 (LGS).
OPEN_CIRCUIT
^ Check resistance > 1M Ohm

Connectors C661, ECM C637 (B).
CONNECTOR
^ Check for connector not correctly latched, backed out pins, damaged pins, corroded pins.

Alarm ECU Faulty.
CHECK THE FOLLOWING:
^ Carry out BCU diagnostics.
POSSIBLE FAULTS
^ Problem with alarm ECU (BCU).

Alarm ECU Not Fitted.
CHECK THE FOLLOWING:
^ Verify that the vehicle is intended to have an alarm. If so check that market programming options are correct and that the correct ECUs are present.
^ If the vehicle is not intended to have robust security re-program the Motronic ECM for non-robust security.
POSSIBLE FAULTS
^ Problem with vehicle configuration.
^ Problem with ECM security set-up.