Toyota 4Runner: No Communication in Immobiliser System (B2796,B2798)

Toyota 4Runner Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Engine Immobiliser System(w/o Smart Key System) / No Communication in Immobiliser System (B2796,B2798)

DESCRIPTION

DTC B2796 is stored when a key is inserted into the ignition key cylinder but no communication occurs between the key and transponder key ECU assembly.
DTC B2798 is stored when a key is inserted into the ignition key cylinder but a communication error occurs between the key and transponder key ECU assembly.

DTC Code	DTC Detection Condition	Trouble Area
B2796	The key code cannot be transmitted.	Key Harness or connector Transponder key ECU assembly Transponder key amplifier
B2798	Key code identification cannot be completed within the specified time.	Key

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When the transponder key ECU assembly is replaced, refer to Registration (See page ).

PROCEDURE

CLEAR DTC

(a) Clear the DTCs (See page ).

2.	CHECK FOR DTC

(a) Check for DTCs (See page ).

OK:

DTC B2796 or B2798 is not output.

USE SIMULATION METHOD TO CHECK

3.	READ VALUE USING TECHSTREAM (ENGINE IMMOBILISER SYSTEM)

(a) Use the Data List to check if the engine immobiliser system is functioning properly (See page ).

Immobiliser

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Immobiliser	Immobiliser system status / Set or Unset	Set: No key in ignition key cylinder Unset: Key inserted in ignition key cylinder	-

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Immobiliser

Immobiliser system status / Set or Unset

Set: No key in ignition key cylinder

Unset: Key inserted in ignition key cylinder

OK:

Set (the key is not inserted in the ignition key cylinder) and Unset (the key is inserted in the ignition key cylinder) appear on the screen according to the key insertion condition.

REPLACE TRANSPONDER KEY ECU ASSEMBLY

4.	CHECK WHETHER ENGINE STARTS WITH OTHER KEYS

(a) Check if the engine starts with an already registered vehicle key.

OK:

Engine starts.

REREGISTER KEY CODE OR REPLACE KEY THAT CANNOT START ENGINE

5.	CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - TRANSPONDER KEY AMPLIFIER)

(a) Disconnect the F34 ECU connector.

(b) Disconnect the F17 amplifier connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F34-14 (VC5) - F17-1 (VC5)	Always	Below 1 Ω
F34-15 (CODE) - F17-4 (CODE)
F34-4 (TXCT) - F17-5 (TXCT)
F34-5 (AGND) - F17-7 (AGND)
F34-14 (VC5) or F17-1 (VC5) - Body ground	Always	10 kΩ or higher
F34-15 (CODE) or F17-4 (CODE) - Body ground
F34-4 (TXCT) or F17-5 (TXCT) - Body ground
F34-5 (AGND) or F17-7 (AGND) - Body ground

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	REPLACE TRANSPONDER KEY AMPLIFIER

(a) Temporarily replace the transponder key amplifier with a new or normally functioning one (See page ).

7.	CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts normally.

OK:

Engine starts normally.

END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)

REPLACE TRANSPONDER KEY ECU ASSEMBLY

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