Theft Deterrent Keyless Entry. Dtc B2796 No Communication In Immobiliser System

DTC B2796 is stored when a key is inserted into the ignition key cylinder but no communication occurs between the key and transponder key ECU assembly.

DTC Code	DTC Detection Condition	Trouble Area	DTC Output Confirmation Operation
B2796	The key code cannot be transmitted (1 trip detection logic*).	Key Harness or connector Transponder key ECU assembly Transponder key amplifier	Insert the key into the ignition key cylinder.

*: 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 Code	Data List and Active Test
B2796	Response

WIRING DIAGRAM

Yaris. Ncp93, 131.Theft Deterrent Keyless Entry.Engine Immobiliser System (For Sedan).
Dtc
B2796 No Communication In Immobiliser System

INSPECTION PROCEDURE

NOTICE:

When replacing the transponder key ECU assembly or key, refer to the Registration (YARIS_NCP93 RM00000120Y021X.html).
After performing repairs, perform the operation that fulfills the DTC output confirmation operation, and then confirm that no DTCs are output again.

1.CLEAR DTC

Clear the DTCs (YARIS_NCP93 RM000001TCQ01OX.html).

NEXT

2.CHECK FOR DTC

Insert and remove each registered key one at a time, and check for DTC each time (YARIS_NCP93 RM000001TCQ01OX.html).
HINT:
1. Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.
2. If DTC B2796 is stored, check for DTCs with the next key after clearing the DTCs.
OK:
DTC B2796 is not output.
Result
Result
Proceed to
OK
A
NG (all keys)
B
NG (any key)
C

Result
Result	Proceed to
OK	A
NG (all keys)	B
NG (any key)	C

Go to step 3

REPLACE KEY THAT CANNOT START ENGINE

USE SIMULATION METHOD TO CHECK (YARIS_NCP93 RM00000135202EX.html)

3.CHECK CONNECTION OF CONNECTOR

Check the connection of the transponder key ECU assembly and transponder key amplifier connectors.

Visually inspect the terminals of the transponder key ECU assembly and transponder key amplifier connectors.
OK:
Connectors are properly connected.

CONNECT CONNECTORS PROPERLY

OK

4.CHECK WHETHER ENGINE STARTS

Check that the engine starts with an already registered vehicle key.
OK:
Engine starts normally.

Go to step 7

OK

5.CLEAR DTC

Clear the DTCs (YARIS_NCP93 RM000001TCQ01OX.html).

NEXT

6.CHECK FOR DTC

Check for DTCs (YARIS_NCP93 RM000001TCQ01OX.html).
HINT:
Before checking for DTCs, perform the "DTC Output Confirmation Operation" procedure.
OK:
DTC B2796 is not output.

Go to step 7

END (CONNECTOR WAS NOT PROPERLY CONNECTED)

7.CHECK TRANSPONDER KEY AMPLIFIER

Using an oscilloscope, check the waveform.
1. Waveform 1 (Reference)
  Measurement Condition
  Item
  Content
  Tester Connection
  D140-1 (VC5) - Body ground
  Tool Setting
  1 V/DIV., 20 ms./DIV.
  Condition
  Key inserted in ignition key cylinder
2. Waveform 2 (Reference)
  Measurement Condition
  Item
  Content
  Tester Connection
  D140-5 (TXCT) - Body ground
  Tool Setting
  1 V/DIV., 20 ms./DIV.
  Condition
  Key inserted in ignition key cylinder
3. Waveform 3 (Reference)
  Measurement Condition
  Item
  Content
  Tester Connection
  D140-4 (CODE) - Body ground
  Tool Setting
  1 V/DIV., 20 ms./DIV.
  Condition
  Key inserted in ignition key cylinder
  OK:
  Waveform is output normally (refer to illustration).
  Text in Illustration
  *a
  Component with harness connected
  (Transponder Key Amplifier)
  *b
  Waveform 1
  *c
  Waveform 2
  *d
  Waveform 3
  Result
  Result
  Proceed to
  OK
  A
  NG (Waveform 1)
  B
  NG (Waveform 2)
  C
  NG (Waveform 3)
  D

Measurement Condition
Item	Content
Tester Connection	D140-1 (VC5) - Body ground
Tool Setting	1 V/DIV., 20 ms./DIV.
Condition	Key inserted in ignition key cylinder

Measurement Condition
Item	Content
Tester Connection	D140-5 (TXCT) - Body ground
Tool Setting	1 V/DIV., 20 ms./DIV.
Condition	Key inserted in ignition key cylinder

Measurement Condition
Item	Content
Tester Connection	D140-4 (CODE) - Body ground
Tool Setting	1 V/DIV., 20 ms./DIV.
Condition	Key inserted in ignition key cylinder

Text in Illustration
*a	Component with harness connected (Transponder Key Amplifier)
*b	Waveform 1
*c	Waveform 2
*d	Waveform 3

Result
Result	Proceed to
OK	A
NG (Waveform 1)	B
NG (Waveform 2)	C
NG (Waveform 3)	D

Go to step 8

Go to step 10

Go to step 12

REPLACE TRANSPONDER KEY ECU ASSEMBLY (YARIS_NCP93 RM000004E7M008X.html)

8.CHECK TRANSPONDER KEY AMPLIFIER (VC5)

Disconnect the D140 transponder key amplifier connector.

Using an oscilloscope, check the waveform.
1. Waveform (Reference)
  Measurement Condition
  Item
  Content
  Tester Connection
  D140-1 (VC5) - Body ground
  Tool Setting
  1 V/DIV., 20 ms./DIV.
  Condition
  Key inserted in ignition key cylinder
  OK:
  Waveform is output normally (refer to illustration).
  Text in Illustration
  *a
  Front view of wire harness connector
  (to Transponder Key Amplifier)
  *b
  Waveform

Go to step 9

REPLACE TRANSPONDER KEY AMPLIFIER (YARIS_NCP93 RM000003RZI00HX.html)

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

Disconnect the D140 transponder key amplifier connector.

Disconnect the D139 transponder key ECU assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
D140-1 (VC5) - D139-14 (VC5)
Always
Below 1 Ω
D140-7 (AGND) - F54-5 (AGND)
Always
Below 1 Ω
D140-1 (VC5) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE TRANSPONDER KEY ECU ASSEMBLY (YARIS_NCP93 RM000004E7M008X.html)

10.CHECK TRANSPONDER KEY AMPLIFIER (TXCT)

Disconnect the D140 transponder key amplifier connector.

Using an oscilloscope, check the waveform.
1. Waveform (Reference)
  Measurement Condition
  Item
  Content
  Tester Connection
  D140-5 (TXCT) - Body ground
  Tool Setting
  1 V/DIV., 20 ms./DIV.
  Condition
  Key inserted in ignition key cylinder
  OK:
  Waveform is output normally (refer to illustration).
  Text in Illustration
  *a
  Front view of wire harness connector
  (to Transponder Key Amplifier)
  *b
  Waveform

Go to step 11

REPLACE TRANSPONDER KEY AMPLIFIER (YARIS_NCP93 RM000003RZI00HX.html)

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

Disconnect the D140 transponder key amplifier connector.

Disconnect the D139 transponder key ECU assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
D140-5 (TXCT) - D139-4 (TXCT)
Always
Below 1 Ω
D140-5 (TXCT) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE TRANSPONDER KEY ECU ASSEMBLY (YARIS_NCP93 RM000004E7M008X.html)

12.CHECK TRANSPONDER KEY AMPLIFIER (CODE)

Disconnect the D140 transponder key amplifier connector.

Using an oscilloscope, check the waveform.
1. Waveform (Reference)
  Measurement Condition
  Item
  Content
  Tester Connection
  D140-4 (CODE) - Body ground
  Tool Setting
  1 V/DIV., 20 ms./DIV.
  Condition
  Key inserted in ignition key cylinder
  OK:
  Waveform is output normally (refer to illustration).
  Text in Illustration
  *a
  Front view of wire harness connector
  (to Transponder Key Amplifier)
  *b
  Waveform

Go to step 13

REPLACE TRANSPONDER KEY AMPLIFIER (YARIS_NCP93 RM000003RZI00HX.html)

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

Disconnect the D140 transponder key amplifier connector.

Disconnect the D139 transponder key ECU assembly connector.

Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection
Condition
Specified Condition
D140-4 (CODE) - D139-15 (CODE)
Always
Below 1 Ω
D140-4 (CODE) - Body ground
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE TRANSPONDER KEY ECU ASSEMBLY (YARIS_NCP93 RM000004E7M008X.html)

*a	Front view of wire harness connector (to Transponder Key Amplifier)
*b	Waveform

Tester Connection	Condition	Specified Condition
D140-1 (VC5) - D139-14 (VC5)	Always	Below 1 Ω
D140-7 (AGND) - F54-5 (AGND)	Always	Below 1 Ω
D140-1 (VC5) - Body ground	Always	10 kΩ or higher