Toyota Tacoma (2015-2018) Service Manual: Transponder Chip Malfunction (B2793,B2794,B2797,B2798)

Toyota Tacoma (2015-2018) Service Manual / Engine Immobiliser / Engine Immobiliser System(w/o Smart Key System) / Transponder Chip Malfunction (B2793,B2794,B2797,B2798)

DESCRIPTION

DTC B2793 is stored when a malfunction is found in the key during key code registration or a key code is not registered normally. Replace the key if key code registration cannot be performed normally and this DTC is output.
DTC B2794 is stored when a key with an incomplete key code is inserted into the ignition key cylinder.
DTC B2797 is stored when a key with a BCC malfunction is inserted into the ignition key cylinder.
DTC B2798 is stored when a key is inserted into the ignition key cylinder but a communication error occurs between the key and transponder key ECU assembly.

DTC Code	DTC Detection Condition	Trouble Area	DTC Output Confirmation Operation
B2793	A transponder chip malfunction (1 trip detection logic*).	Key Transponder key coil Transponder key ECU assembly	Insert the key into the ignition key cylinder, turn the ignition switch from off to ON and wait at least 20 seconds.
B2794	A key with an incomplete key ID code is used to turn the ignition switch to ON (1 trip detection logic*).
B2797	A key with a BCC malfunction is used to turn the ignition switch to ON (1 trip detection logic*).
B2798	Key ID code identification cannot be completed within the specified time (1 trip detection logic*).

*: Only output while a malfunction is present.

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Operation when Malfunction Detected
Engine cannot be started	-

Related Data List and Active Test

DTC No.	Data List and Active Test
B2793	-
B2794	-
B2797	-
B2798	-

CAUTION / NOTICE / HINT

NOTICE:

If the transponder key ECU assembly or key is replaced, refer to Registration (See page ).
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

PROCEDURE

CLEAR DTC

(a) Clear the DTCs (See page ).

2.	CHECK DTC OUTPUT

(a) Perform "DTC Output Confirmation Operation" procedure.

(b) Check for DTCs (See page HINT: ).

HINT:

If DTC B2793, B2794, B2797, or B2798 is stored, clear the DTCs before checking the next key.

OK:

DTC B2793, B2974, B2797 and B2798 are not output.

Result

Result	Proceed to
DTCs are output for all of the keys	A
DTCs are output for any of the keys	B
DTCs are not output	C

REPLACE KEY THAT DTC IS OUTPUT

USE SIMULATION METHOD TO CHECK

3.	CHECK CONNECTION OF CONNECTOR

(a) Check that the connector is properly connected to the transponder key coil.

(b) Check that the engine starts with the key.

OK:

Engine starts normally.

END (CONNECTOR WAS NOT CONNECTED PROPERLY)

4.	REPLACE TRANSPONDER KEY COIL

(a) Clear the DTCs (See page (b) Replace the transponder key coil (See page ).

(b) Replace the transponder key coil (See page (c) Check that the engine starts with the key (See page ).

OK:

Engine starts normally.

END (TRANSPONDER KEY COIL WAS DEFECTIVE)

REPLACE TRANSPONDER KEY ECU ASSEMBLY

Antenna Coil Open / Short (B2784)

DESCRIPTION When an open or short circuit is detected in the antenna coil built into the transponder key coil, the transponder key ECU assembly stores this DTC. DTC No. DTC D ...

Engine does not Start because No Initial Combustion

DESCRIPTION When a key is inserted into the ignition key cylinder, the transponder key coil receives the key ID code and sends it to the transponder key ECU assembly. If an error i ...

Other materials:

Radar Cruise Control Presence Determination Malfunction (Engine / HV) (C1A52)
DESCRIPTION DTC C1A52 is stored when the ECM cannot recognize the millimeter wave radar sensor assembly. DTC No. Detection Item DTC Detection Condition Trouble Area MIL C1A52 Radar Cruise Control Presence Determin ...

Removal
REMOVAL PROCEDURE 1. PRECAUTION NOTICE: After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before pr ...

Test Mode Procedure
TEST MODE PROCEDURE 1. TEST MODE (SIGNAL CHECK MODE) PROCEDURE HINT: When entering test mode (signal check mode), the tire pressure warning ECU and receiver stores all the test mode (signal check mode) DTCs first. After the tire pressure warning ECU and receiver completes the signa ...