Toyota Sienna Service Manual: No Communication in Immobiliser System

Toyota Sienna Service Manual / Engine immobiliser / Problem symptoms table / Diagnostic trouble code chart / No Communication in Immobiliser System

DTC B2796 No Communication in Immobiliser System

DTC B2798 Communication Malfunction No. 2

DESCRIPTION

These codes are stored in the memory when a key that does not have a transponder chip is inserted or if communication between the key and transponder key ECU is impossible.

DTC No.	DTC Detection Condition	Trouble Area
B2796	No communication	Key Wire harness Transponder key amplifier Transponder key ECU assembly
B2798	Communication error	Key

WIRING DIAGRAM

WIRING DIAGRAM

INSPECTION PROCEDURE

1 READ VALUE OF INTELLIGENT TESTER

Connect the intelligent tester (with CAN VIM) to the DLC3.
Turn the ignition switch on and turn the intelligent tester main switch on.
Select IMMOBILISER in the DATA LIST and read the value displayed on the intelligent tester.

Transponder key ECU:

Transponder key ECU

OK: UNSET (Ignition switch on) appears on the screen.

2 CHECK KEYS

Insert the vehicle's other key into the ignition key cylinder.
Check that the engine starts with this key.

OK: The engine starts

3 READ VALUE OF INTELLIGENT TESTER

Connect the intelligent tester (with CAN VIM) to the DLC3.
Turn the ignition switch on and turn the intelligent tester main switch on.
Select ANTENNA COIL in the DATA LIST and read the value displayed on the intelligent tester

Transponder key ECU:

Transponder key ECU

OK: NORMAL (Antenna coil is normal) appears on the screen.

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

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

Disconnect the T6 ECU and I14 amplifier connectors.
Measure the resistance according to the value(s) in the table below.

Resistance

Resistance

5 INSPECT TRANSPONDER KEY ECU ASSEMBLY

INSPECT TRANSPONDER KEY ECU ASSEMBLY

Reconnect the T6 ECU and I14 amplifier connectors.
Measure the voltage according to the value(s) in the table below.

Voltage

Voltage

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

Resistance

Resistance

6 REPLACE TRANSPONDER KEY AMPLIFIER

After replacing the transponder key amplifier with a normally functioning transponder key amplifier, check that the engine starts.

OK: The engine starts.

END (TRANSPONDER KEY AMPLIFIER DEFECTIVE)

DTC B2797 Communication Malfunction No. 1

DESCRIPTION

This DTC is output when an error occurs in normal communication.

HINT: Some noise found in the communication line.

DTC No.	DTC Detection Condition	Trouble Area
B2797	Keys are positioned too close to each other, or noise occurred in communication line.	Key Transponder key amplifier Wire harness Transponder key ECU assembly

WIRING DIAGRAM

WIRING DIAGRAM

INSPECTION PROCEDURE

1 CHECK KEY

CHECK KEY

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.

Result

Result

2 CHECK DTC OUTPUT

Delete the DTC
Insert the key into the ignition key cylinder.
Check that no code is output.

OK: No DTC is output.

3 CHECK TRANSPONDER KEY AMPLIFIER

CHECK TRANSPONDER KEY AMPLIFIER

Using an oscilloscope or the intelligent tester, check the waveform between the terminals of the I14 amplifier and T6 ECU connector.
Check that no noise is included in the waveform (an example of noise is shown on the left).
Check that no noise is included in the waveform (an example of noise is shown on the left).

Result

Result

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

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

Disconnect the T6 ECU and I14 amplifier connectors.
Measure the resistance according to the value(s) in the table below.

Resistance

Resistance

5 REPLACE TRANSPONDER KEY AMPLIFIER

After replacing the transponder key amplifier with a normally functioning transponder key amplifier, check that the engine starts.

OK: The engine starts

END (TRANSPONDER KEY AMPLIFIER DEFECTIVE)

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