Toyota Tundra. Manual — part 371

Fig. 21: Checking Harness And Connector (Transponder Key ECU - Transponder Key
Amplifier)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to Next Step

6. REPLACE TRANSPONDER KEY AMPLIFIER

a. Temporarily replace the transponder key amplifier with a new or normally functioning one (see

REMOVAL ).

7. CHECK WHETHER ENGINE STARTS

a. Check that the engine starts normally.

OK: Engine starts normally.

NG: REPLACE TRANSPONDER KEY ECU (see REMOVAL )

OK: END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)

DTC B2797 COMMUNICATION MALFUNCTION NO. 1

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra

DESCRIPTION

This DTC is output when a communication error occurs between the transponder key amplifier and transponder
key ECU. Some possible reasons for the communication error are: 1) 2 or more ignition keys are positioned too
close together, or 2) noise is occurring in the communication line.

DTC B2797 COMMUNICATION MALFUNCTION NO. 1 DETECTION CONDITION CHART

WIRING DIAGRAM

Fig. 22: Communication Malfunction No. 1 - 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. CHECK KEY

a. Check whether the ignition key being used is near other ignition keys, as shown in the illustration.

Also, check whether the key ring is in contact with the key grip.

DTC

Code

DTC Detection Condition

Trouble Area

B2797

Keys are positioned too close to each other, or noise occurred in
communication line



Key



Harness or connector



Transponder key
amplifier



Transponder key ECU

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra

Fig. 23: Identifying Ignition Key
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Result

IGNITION KEY RESULT CHART

B: Go to step 3

A: Go to Next Step

2. CHECK FOR DTC

a. Separate the keys from each other, or remove the key ring.

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

c. Insert a key into the ignition key cylinder. Remove it. Repeat for all other keys.

d. Check that no DTC is output (see DTC CHECK/CLEAR ).

OK: DTC B2797 is not output.

NG: Go to step 3

OK: END

3. CHECK TRANSPONDER KEY ECU (NOISE)

a. Using an oscilloscope or the Techstream, check for noise in the waveform between the terminals of

the J20 amplifier connector and J26 ECU connector.

OK

TRANSPONDER KEY ECU (NOISE) TESTER CONNECTION SPECIFIED CONDITION

Result

Proceed to

Key is near other keys and/or key ring is in contact with key grip

A

Key is not near other keys and/or key ring is not in contact with key grip

B

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra

CHART

Fig. 24: Identifying J20 Amplifier Connector And J26 ECU Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

NG: FIND CAUSE OF NOISE AND REMOVE IT

OK: Go to Next Step

4. 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

Tester Connection

Tool Setting

Condition

Specified

Condition

J26-15 (CODE) - J20-4

(CODE)

5 V/DIV., 20

msec./DIV.

Key inserted in ignition key

cylinder

No noise is

present

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Engine Immobilizer - Tundra