Toyota Tundra. Manual — part 370

a. Clear the DTC (see DTC CHECK/CLEAR ).

7. CHECK FOR DTC

a. Check for DTC (see DTC CHECK/CLEAR ).

OK: DTC B2784 is not output.

NG: REPLACE TRANSPONDER KEY ECU (see REMOVAL )

OK: END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)

DTC B2793 TRANSPONDER CHIP MALFUNCTION; DTC B2794 UNMATCHED ENCRYPTION
CODE; DTC B2795 UNMATCHED KEY CODE

DESCRIPTION



B2793 is output when a malfunction is found in the key during key code registration or a key code is not
registered normally. Replace the key if the key code registration cannot be performed normally and this
DTC is detected.



B2794 is output when a key with an incomplete key code is inserted into the ignition key cylinder.



B2795 is output when a key with a key code that has not been registered in the ECU is inserted into the
ignition key cylinder.

DTC B2793, B2794, B2795 DETECTION CONDITION CHART

INSPECTION PROCEDURE

HINT:

When the transponder key ECU is replaced, reregister the ECU - ECM communication ID (see
REGISTRATION).

1. REREGISTER KEY

a. Clear the DTCs (see DTC CHECK/CLEAR ).

b. Reregister the key code with the transponder key ECU (see REGISTRATION ).

c. Check that the engine starts with the key.

OK: Engine starts.

NG: REPLACE KEY

OK: END

DTC Code

DTC Detection Condition

Trouble Area

B2793

Transponder chip malfunction

Key

B2794

Key with incomplete key code is inserted

B2795

Key with unregistered key code is inserted

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra

DTC B2796 NO COMMUNICATION IN IMMOBILIZER SYSTEM; DTC B2798 COMMUNICATION
MALFUNCTION NO. 2

DESCRIPTION



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



DTC B2798 is output when a key is inserted into the ignition key cylinder but a communication error
occurs between the key and transponder key ECU.

DTC B2796 AND B2798 DETECTION CONDITION CHART

WIRING DIAGRAM

DTC

Code

DTC Detection Condition

Trouble Area

B2796

The key code cannot be transmitted



Key



Harness or connector



Transponder key ECU



Transponder key
amplifier

B2798

Key code identification cannot be completed within the
specified time

Key

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra

Fig. 20: No Communication In Immobilizer System - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

INSPECTION PROCEDURE

HINT:

When the transponder key ECU is replaced, reregister the ECU - ECM communication ID (see
REGISTRATION).

1. CLEAR DTC

a. Clear the DTC (see DTC CHECK/CLEAR ).

2. CHECK FOR DTC

a. Check for DTC (see DTC CHECK/CLEAR ).

OK: DTC B2796 or B2798 is not output.

NG: Go to step 3

OK: USE SIMULATION METHOD TO CHECK (See HOW TO PROCEED WITH
TROUBLESHOOTING )

3. READ VALUE OF TECHSTREAM (ENGINE IMMOBILIZER SYSTEM)

a. Use the Data List to check if the engine immobilizer system is functioning properly.

DATA LIST - IMMOBILIZER

OK: UNSET (key is in ignition key cylinder) appears on the screen.

NG: Go to step 4

OK: REPLACE TRANSPONDER KEY ECU (see REMOVAL )

4. CHECK WHETHER ENGINE STARTS WITH OTHER KEYS

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

OK: Engine starts.

NG: Go to step 5

Tester

Display

Measurement Item / Display

Normal Condition

Diagnostic

Note

Immobilizer

Immobilizer system status / Set or

Unset

Set: No key is in ignition key
cylinder
Unset: Key is in ignition key
cylinder

-

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra

OK: REREGISTER KEY CODE OR REPLACE KEY THAT CANNOT START ENGINE

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

AMPLIFIER)

a. Disconnect the J26 ECU connector.

b. Disconnect the J20 amplifier connector.

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

Standard resistance

HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - TRANSPONDER KEY
AMPLIFIER) TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection

Condition Specified Condition

J26-14(VC5) - J20-1 (VC5)

Always

Below 1 ohms

J26-15(CODE) - J20-4 (CODE)

J26-4 (TXCT) - J20-5 (TXCT)

J26-5 (AGND) - J20-7 (AGND)

J26-14 (VC5) or J20-1 (VC5) - Body ground

Always

10 kohms or higher

J26-15(CODE) or J20-4 (CODE) - Body ground

J26-4 (TXCT) or J20-5 (TXCT) - Body ground

J26-5 (AGND) or J20-7 (AGND) - Body ground

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra