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

Toyota 4Runner Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Engine Immobiliser System(w/o Smart Key System) / 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

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

GO TO STEP 3

2.	CHECK FOR DTC

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

(b) Clear the DTCs (See page ).

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

OK:

DTC B2797 is not output.

END

3.	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
F34-15 (CODE) - F17-4 (CODE)	Always	Below 1 Ω
F34-15 (CODE) or F17-4 (CODE) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Component with harness connected

(Transponder Key Amplifier)

Component with harness connected

(Transponder Key ECU Assembly)

Noise should not appear

FIND CAUSE OF NOISE AND REMOVE IT

5.	REPLACE TRANSPONDER KEY AMPLIFIER

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

6.	CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts normally.

OK:

Engine starts.

END (TRANSPONDER KEY AMPLIFIER IS DEFECTIVE)

REPLACE TRANSPONDER KEY ECU ASSEMBLY

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