Lexus NX: Engine Immobiliser System Malfunction (B2799-790)

DESCRIPTION

When there is a communication malfunction between the hybrid vehicle control ECU and ID code box (immobiliser code ECU), or when the communication ID codes do not match, the hybrid vehicle control ECU stores this DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2799-790	Engine Immobiliser System Malfunction	Either condition is met (1 trip detection logic*): A malfunction in the communication or communication lines between the hybrid vehicle control ECU and ID code box (immobiliser code ECU). A matching communication code cannot be verified during communication between the hybrid vehicle control ECU and ID code box (immobiliser code ECU).	ID code box (immobiliser code ECU) Hybrid vehicle control ECU Harness or connector	DTC output confirmation operation (Either condition is met): Within 10 seconds of a hybrid control system start operation being performed (with the shift lever in P and the brake pedal depressed, the power switch is pressed while the key is being carried). If there is a malfunction, the hybrid control system stops (communication begins within 3 seconds of the hybrid control system start operation being performed, and DTCs are stored after 6 seconds). 10 seconds after the power switch is turned on (IG) after reconnecting the cable to the negative (-) auxiliary battery terminal (communication begins within 3 seconds of the power switch being turned on (IG), and DTCs are stored after 6 seconds).

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Operation when Malfunction Detected
Hybrid control system cannot be started	-

Related Data List and Active Test

DTC No.	Data List and Active Test
B2799-790	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

When DTC B2799-790 and the certification ECU (smart key ECU assembly) DTC are output simultaneously, first perform troubleshooting for the certification ECU (smart key ECU assembly) DTC.

PROCEDURE

1.	REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID.

Click here

NEXT

2.

CLEAR DTC

(a) Clear the DTCs.

Powertrain > Hybrid Control > Clear DTCs

NEXT

3.	CHECK FOR DTC

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

(b) Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes

OK:

B2799-790 is not output.

OK

END (COMMUNICATION ID REGISTRATION WAS DEFECTIVE)

NG

4.	CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - HYBRID VEHICLE CONTROL ECU)

(a) Disconnect the I26 ID code box (immobiliser code ECU) connector.

(b) Disconnect the I116 hybrid vehicle control ECU connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
I26-4 (EFIO) - I116-22 (IMI)	Always	Below 1 Ω
I26-3 (EFII) - I116-23 (IMO)	Always	Below 1 Ω
I26-4 (EFIO) or I116-22 (IMI) - Body ground	Always	10 kΩ or higher
I26-3 (EFII) or I116-23 (IMO) - Body ground	Always	10 kΩ or higher

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REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.	REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

(a) Replace the ID code box (immobiliser code ECU) with a new one.

Click here

NEXT

6.	REGISTER RECOGNITION CODE

(a) Register the recognition codes in the ECUs.

Click here

NEXT

7.	REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID.

Click here

NEXT

8.

CLEAR DTC

(a) Clear the DTCs.

Powertrain > Hybrid Control > Clear DTCs

NEXT

9.	CHECK FOR DTC

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

(b) Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes

OK:

B2799-790 is not output.

OK

END (ID CODE BOX (IMMOBILISER CODE ECU) WAS DEFECTIVE)

NG

REPLACE HYBRID VEHICLE CONTROL ECU

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