B3929

DTC B3925, B3929, or B3977

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC B3925 00
- Wrong Environment Identifier Received IPC (Instrument)

DTC B3929 00
- Wrong Environment Identifier Received REC (Rear Electrical Centre)

DTC B3977 00
- Wrong Environment Identifier Received UEC (Underhood Electrical Centre)




Circuit/System Description

When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used as a means to discourage vehicle theft by means of swapping modules between vehicles.


The steering column module (CIM) is the keeper of the environment identifier. The instrument panel cluster (IPC), underhood electrical center (UEC), and rear electrical center (REC) each learn the environment identifier during their configuration process. During vehicle operation, each of these modules report their environment identifier to the CIM. The CIM compares the received environment identifiers to its own stored identifier. If the identifiers match, vehicle starting is allowed. If two or more non-matching environment identifiers are received by the CIM, vehicle starting is disabled.


Conditions for Running the DTC

Ignition ON


Conditions for Setting the DTC

An incorrect environment identifier is received by the CIM


Action Taken When the DTC Sets

* Vehicle starting is disabled
* The Service Vehicle Soon indicator will flash



Conditions for Clearing the DTC

* A current DTC will be cleared when the CIM receives a correct environment identifier.
* A history DTC will clear after 100 malfunction free ignition cycles.



Reference Information
Schematic Reference

Immobilizer Schematics (Immobilizer Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Immobilizer Description and Operation (Immobilizer Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information


Circuit/System Verification


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 appropriate control module.
2. Perform the Programming and Setup procedure for the appropriate control module. Refer to Control Module References (Programming and Relearning) for programming and setup procedures. Verify the DTC does not reset after programming.

• If the DTC resets, replace the appropriate control module.




Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Control Module References (Programming and Relearning)for IPC, REC, or UEC replacement, programming, and setup