Page 3265 of 4500
a. Check if the engine starts with the vehicle's other keys.
OK: Engine starts.
NG: Go to step 3
OK: RE-REGISTER OR REPLACE KEY THAT CANNOT START ENGINE
3.CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY - TRANSPONDER KEY
AMPLIFIER)
a. Disconnect the T9 ECU connector.
b. Disconnect the T8 amplifier connector.
c. Measure the resistance of the wire harness side connectors.
Page 3267 of 4500

Fig. 36: Identifying T9 ECU And T8 Amplifier Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TRANSPONDER KEY ECU - TRANSPONDER KEY AMPLIFIER - RESISTANCE TABLE
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
4.CHECK OPERATION OF TRANSPONDER KEY AMPLIFIER
a. After replacing the transponder key amplifier with a normally functioning amplifier, check that the
engine starts.
OK: Engine starts.
NG: REPLACE TRANSPONDER KEY ECU ASSY
OK: END
CIRCUIT 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. Follow the inspection procedure below.
Fig. 37: DTC Reference Chart
Tester connectionSpecified condition
T9-9 (VC5) - T8-1 (+B)Below 1ohms
T9-10 (CODE) - T8-4 (CODE)Below 1ohms
T9-12 (TXCT) - T8-5 (TXCT)Below 1 ohms
T9-13 (AGND) - T8-7 (GND)Below 1 ohms
T9-9 (VC5) or T8-1 (+B) - Body ground10 kohms or higher
T9-10 (CODE) or T8-4 (CODE) - Body ground10 kohms or higher
T9-12 (TXCT) or T8-5 (TXCT) - Body ground10 kohms or higher
T9-13 (AGND) or T8-7 (GND) - Body ground10 kohms or higher
Page 3268 of 4500
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WIRING DIAGRAM
Fig. 38: DTC B2797
- Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK KEYS
a. Check if the ignition key being used is near other ignition keys, as shown in the illustration. Also,
check if the ke
y ring is in contact with the key grip.
Page 3269 of 4500
Fig. 39: Checking Keys
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Result:
CHECKING KEY RESULT TABLE
B: Go to step 3
A: Go to next step
ResultProceed to
Key is near other keys and/or key rings is in contact with key grip.A
Key is not near other keys and/or key ring is not in contact with the key grip.B
Page 3270 of 4500
2.CHECK FOR DTCS
a. Separate the keys from each other. Or, remove the key ring.
b. Delete the DTC (see DTC CHECK/CLEAR
).
c. Insert a key into the ignition cylinder. Remove it. Repeat for all the other keys.
d. Check that no code is output.
NG: Go to step 3
OK: END
3.CHECK TRANSPONDER KEY ECU ASSY
a. Using an oscilloscope or the hand-held tester, check the waveform between the terminals of the T8
amplifier connector and T9 ECU connector. The waveform should be similar to the illustration .
OK: No noise present (see illustration ).
Fig. 40: Identifying Waveform
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WAVEFORM REFERENCE TABLE
TOOL SETTING REFERENCE TABLE
Tester connectionSpecified condition
T9-10 (CODE) - T8-4 (CODE)No noise is present
Page 3271 of 4500
NG: FIND CAUSE OF NOISE AND REMOVE IT
OK: Go to next step
4.CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY - TRANSPONDER KEY
AMPLIFIER)
a. Disconnect the T9 ECU connector.
b. Disconnect the T8 amplifier connector.
c. Measure the resistance of the wire harness side connectors.
Tool Setting10 V/DIV.,20 ms/DIV.
ConditionIgnition switch OFF --> ON
Page 3273 of 4500

Fig. 41: Identifying T9 And T8 Amplifier Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
Standard:
TRANSPONDER KEY ECU - TRANSPONDER KEY AMPLIFIER - RESISTANCE TABLE
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR
OK: Go to next step
5.CHECK OPERATION OF TRANSPONDER KEY AMPLIFIER
a. After replacing the transponder key amplifier with a normally functioning amplifier, check that the
engine starts.
OK: Engine starts.
NG: REPLACE TRANSPONDER KEY ECU ASSY
OK: END
CIRCUIT DESCRIPTION
This DTC is output when: 1) the ECM detects errors in its own communications with the transponder key ECU;
2) the ECM detects errors in the communication lines; and 3) the ECU communication ID between the
transponder key ECU and the ECM are different and an engine start is attempted.
Before troubleshooting for this DTC, make sure no transponder key ECU DTCs are present. If the transponder
key ECU has a key code related DTC, repair it first.
Fig. 42: DTC Reference Chart
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
WIRING DIAGRAM
Tester connectionSpecified condition
T9-10 (CODE) - T8-4 (CODE)Below 1 ohms
Page 3274 of 4500
Fig. 43: DTC B2799 - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY - ECM)
a. Disconnect the T9 ECU connector.
b. Disconnect the E2 ECM connector.
c. Measure the resistance of the wire harness side connectors.