Toyota 4Runner manuals

Toyota 4Runner: 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

1.

CLEAR DTC

(a) Clear the DTCs (See page ).


NEXT

2.

CHECK FOR DTC

(a) Check for DTCs (See page ).


OK:

DTC B2796 or B2798 is not output.


OK

USE SIMULATION METHOD TO CHECK

NG

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

-

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.


OK

REPLACE TRANSPONDER KEY ECU ASSEMBLY

NG

4.

CHECK WHETHER ENGINE STARTS WITH OTHER KEYS

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

OK:

Engine starts.


OK

REREGISTER KEY CODE OR REPLACE KEY THAT CANNOT START ENGINE

NG

5.

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

(a) Disconnect the F34 ECU connector.

(b) Disconnect the F17 amplifier connector.

(c) Measure the resistance according to the value(s) in the table below.

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


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.

REPLACE TRANSPONDER KEY AMPLIFIER

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


NEXT

7.

CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts normally.

OK:

Engine starts normally.


OK

END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)


NG

REPLACE TRANSPONDER KEY ECU ASSEMBLY

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