For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC B3901 00: Wrong Enviornment Identifier Received

### 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 enviornment identifier is received by the control module

### 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 module receives a correct environment identifier.

• | A history DTC will clear after 100 malfunction free ignition cycles.

### Reference Information

#### Schematic Reference

Immobilizer Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Immobilizer Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

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

⇒ | If the DTC resets, replace the appropriate module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming