Certain modules use a security code as a means of theft deterrence. Each vehicle is assigned a specific four-digit security code at the time of manufacturer. This security code is used by multiple modules which require a correct security code to operate properly. If a security code is not programming or an incorrect security code is programmed which does not match that of the vehicle, vehicle starting is disabled.

The following modules utilize security code:

Ignition ON

An incorrect security code has been programmed to the ECM

Schematic Reference

Immobilizer Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Immobilizer Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Important: When reprogramming a control module which has already been programmed, additional security measures must be met before reprogramming is allowed. Prior to programming, security access must be granted by connecting a Tech 2 in a pass-thru arraignment and requesting security access in TIS. Once security access is granted, the security code must be entered. The security code can be found in DealerWorld. Both of these security measures must be met before the Reset ECU selection is allowed.

1. Ignition ON, select Reset ECU on the scan tool for the ECM.
2. Perform the Programming and Setup procedure for the ECM. Refer to Control Module References for programming and setup procedures. Verify the DTC does not reset after programming.

⇒	If the DTC resets, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, programming, and setup