Toyota 4Runner manuals

Toyota 4Runner: Communication Malfunction No. 1 (B2797)

DESCRIPTION

This DTC is stored when a communication error occurs between the transponder key amplifier and transponder key ECU assembly. 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 Code

DTC Detection Condition

Trouble Area

B2797

2 or more ignition keys are positioned too close to each other or noise occurs in the communication line.

  • Key
  • Harness or connector
  • Transponder key amplifier
  • Transponder key ECU assembly

WIRING DIAGRAM


CAUTION / NOTICE / HINT

NOTICE:

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


PROCEDURE

1.

CHECK KEY

(a) Check whether the ignition key being used is near other ignition keys, as shown in the illustration. Also, check whether a key ring is in contact with the key grip.

Result

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 key ring is not in contact with key grip

B



B

GO TO STEP 3


A

2.

CHECK FOR DTC

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

(b) Clear the DTCs (See page ).


(c) Insert a key into the ignition key cylinder, and then remove it. Repeat this for all the other keys.

(d) Check that no DTC is output (See page ).


OK:

DTC B2797 is not output.


OK

END


NG

3.

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

F34-15 (CODE) - F17-4 (CODE)

Always

Below 1 Ω

F34-15 (CODE) or F17-4 (CODE) - Body ground

Always

10 kΩ or higher


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

4.

CHECK TRANSPONDER KEY ECU ASSEMBLY (NOISE)

(a) Using an oscilloscope, check for noise in the waveform between the terminals of the F17 amplifier connector and F34 ECU connector.

Measurement Condition

Item

Content

Tester Connection

F17-4 (CODE) - F34-15 (CODE)

Tool Setting

5 V/DIV., 20 ms./DIV.

Condition

Key inserted in ignition key cylinder

OK:

No noise is present.

Text in Illustration

*a

Component with harness connected

(Transponder Key Amplifier)

*b

Component with harness connected

(Transponder Key ECU Assembly)

*c

Noise should not appear



NG

FIND CAUSE OF NOISE AND REMOVE IT


OK

5.

REPLACE TRANSPONDER KEY AMPLIFIER

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



NEXT

6.

CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts normally.

OK:

Engine starts.


OK

END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)


NG

REPLACE TRANSPONDER KEY ECU ASSEMBLY

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