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Lexus DTC B2795 - User Manual

Lexus DTC B2795
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Title:
TROUBLESHOOTING IMMOBILIZER
DTC B2795
Models:
’98 & ’99 All Models
Technical Service
Information Bulletin
March 12, 1999
EL002–99
The Diagnostic Section (DI) of the Repair Manual has been expanded and clarified to
assist in troubleshooting the Engine Immobilizer System. Use this information in
accordance with the current Repair Manual for each model to diagnose the system.
S 1998 and 1999 All Models
DTC B2795 Unmatched Key Code
CIRCUIT DESCRIPTION
The system outputs this DTC when an unregistered key is inserted into the ignition. If
this DTC is outputted, clear the code and insert all registered keys into the vehicle’s
ignition. If a key that outputs B2795 is found, register that key. If this DTC is no longer
outputted, then there is a possibility that an unregistered key could have been inserted in
the past, (System is Normal). Request additional information from the customer as to the
use of the system prior to this condition to find a possible cause. (Example: An
unregistered key has been inserted, etc.)
DTC No. Condition Probable Cause
B2795 S Unmatched Key Code S Key
OP CODE DESCRIPTION TIME OPN T1 T2
N/A Not Applicable to Warranty – – – –
ELECTRICAL
Introduction
Affected
Vehicles
Diagnostic
Procedure
Warranty
Information
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Summary

Introduction and Vehicle Information

Introduction

Provides context for the diagnostic section of the repair manual.

Affected Vehicles

Lists the specific vehicle models covered by this bulletin.

Troubleshooting Immobilizer DTC B2795

Circuit Description

Explains the function and behavior of the immobilizer circuit.

Diagnostic Procedure

Outlines the steps for diagnosing the immobilizer system.

Diagnostic Steps

Details the specific step-by-step procedure for diagnosing DTC B2795.

Warranty Information

Summary

Introduction and Vehicle Information

Introduction

Provides context for the diagnostic section of the repair manual.

Affected Vehicles

Lists the specific vehicle models covered by this bulletin.

Troubleshooting Immobilizer DTC B2795

Circuit Description

Explains the function and behavior of the immobilizer circuit.

Diagnostic Procedure

Outlines the steps for diagnosing the immobilizer system.

Diagnostic Steps

Details the specific step-by-step procedure for diagnosing DTC B2795.

Warranty Information

Overview

  1. Function Description
  2. Important Technical Specifications
  3. Usage Features
  4. Maintenance Features

This document is a Technical Service Information Bulletin (SIB) from Lexus, titled "TROUBLESHOOTING IMMOBILIZER DTC B2795," with the bulletin number EL002-99. It was issued on March 12, 1999, and applies to all 1998 and 1999 Lexus models. The primary function of this bulletin is to provide an expanded and clarified diagnostic procedure for the Engine Immobilizer System, specifically addressing Diagnostic Trouble Code (DTC) B2795, which indicates an "Unmatched Key Code."

Function Description:

The Engine Immobilizer System is a security feature designed to prevent unauthorized starting of the vehicle. It operates by verifying the legitimacy of the key inserted into the ignition. If an unregistered or unrecognized key is used, the system prevents the engine from starting. DTC B2795 is generated when the system detects a key that does not match its registered codes. This bulletin outlines a systematic approach to diagnose and resolve issues related to this specific DTC. The core function of the diagnostic procedure is to identify whether the problem lies with an unregistered key, a faulty key, or a transient issue that has since resolved.

Important Technical Specifications:

  • DTC: B2795
  • Description of DTC B2795: Unmatched Key Code. This means the immobilizer system's Electronic Control Unit (ECU) did not recognize the transponder code from the key inserted into the ignition.
  • Affected Models: All Lexus models from model years 1998 and 1999.
  • System Involved: Engine Immobilizer System.
  • Probable Cause for B2795: An unregistered key was inserted, or the key itself is faulty (e.g., transponder issue).

Usage Features:

The bulletin provides a clear, step-by-step diagnostic procedure for technicians:

  1. Initial Action: The first step is to "Delete the DTC and insert all presently available keys to check whether the engine starts or not." This is crucial for determining if the issue is persistent or if it was a one-time event.
  2. Observation (NOTE): It's noted that "DTC B2795 is stored in memory when a key that is inserted does not start the engine." This clarifies the condition under which the code is logged.
  3. Result Analysis:
    • (A) All keys start the engine: If all available keys successfully start the engine after clearing the DTC, the system is considered "No Problem." The bulletin explains that "DTC B2795 is stored in memory when a key that is inserted does not start the engine," implying that the code might have been triggered by an unregistered key in the past, but the current registered keys are functional. In this scenario, the technician should request additional information from the customer regarding past usage to understand how an unregistered key might have been used.
    • (B) A specific key does not start the engine: If one or more specific keys fail to start the engine, this indicates a problem with those particular keys.
  4. Corrective Action: If a specific key does not start the engine (Result B), the next step is to "Register the key that does not start the engine." This process involves programming the immobilizer system to recognize the transponder code of the problematic key, thereby allowing it to start the vehicle.

The bulletin emphasizes the importance of gathering additional information from the customer regarding the system's use prior to the condition, especially if the system appears normal after diagnosis. This helps in understanding the root cause, such as an unregistered key being inserted by mistake.

Maintenance Features:

While not explicitly a "maintenance" feature in the traditional sense, the bulletin outlines a key maintenance-related procedure:

  • Key Registration: The ability to register new or previously unregistered keys is a critical maintenance function of the immobilizer system. This allows for replacement keys to be programmed or for keys that were previously unrecognized to be integrated into the system. This ensures that the vehicle remains operational even if a key is lost or a new key is acquired.
  • Diagnostic Clarity: By providing a clear diagnostic path, the bulletin aids technicians in efficiently troubleshooting immobilizer issues, reducing diagnostic time and ensuring correct repairs. This contributes to the overall maintainability of the vehicle's security system.
  • Warranty Information: The bulletin includes a "Warranty Information" section, stating "N/A" (Not Applicable to Warranty) for the OP CODE, DESCRIPTION, TIME, OPN, T1, and T2 fields. This indicates that the diagnostic and repair procedures described in this bulletin are generally not covered under warranty, or specific warranty codes are not provided within this document.

In summary, this Lexus SIB serves as a vital guide for technicians to effectively diagnose and resolve issues related to the Engine Immobilizer System when DTC B2795 is present, focusing on key registration and proper diagnostic steps to ensure vehicle security and functionality.

Lexus DTC B2795 Specifications

General IconGeneral
BrandLexus
ModelDTC B2795
CategoryCar Alarm
LanguageEnglish

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