ENGINE IMMOBILISER SYSTEM(w/ Entry and Start System), Diagnostic DTC:B1572

DTC Code	DTC Name
B1572	Immobiliser System Communication Malfunction

DESCRIPTION

The ECM stores this code if a communication problem is detected between the ID code box (immobiliser code ECU)*1 or certification ECU (smart key ECU assembly)*2 and the ECM.

*1: w/ ID Code Box
*2: w/o ID Code Box

DTC Code	DTC Detection Condition	Trouble Area	DTC Output Confirmation Operation
B1572	When there is a problem in communication between the ID code box (immobiliser code ECU)1 or certification ECU (smart key ECU assembly)2 and the ECM (1 trip detection logic*3):	ID code box (immobiliser code ECU)1 Certification ECU (smart key ECU assembly)2 ECM Harness or connector	Engine switch on (IG)

*1: w/ ID Code Box
*2: w/o ID Code Box
*3: 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
B1572	Entry&Start Immobiliser

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Note

Before replacing the certification ECU or ID code box (immobiliser code ECU)*, refer to the entry and start system (for Entry Function) Click here.
After performing repairs, perform the operation that fulfills the DTC output confirmation operation, and then confirm that no DTCs are output again.

*: w/ ID Code Box

PROCEDURE

READ VALUE USING GTS (IMMOBILISER)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Body Electrical / Entry & Start / Data List.

According to the display on the GTS, read the Data List.

Entry & Start
Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Immobiliser	Engine immobiliser system status when power source mode on (IG) / Unset or Set	Set: Engine immobiliser set (engine start prohibited) (engine switch off) Unset: Engine immobiliser unset (engine start permitted) [engine switch on (ACC) or on (IG)]	If "Set" is displayed, the engine start function is prohibited.

OK
On the GTS screen, the display changes between Set and Unset as shown in the table above.

GO TO ENTRY AND START SYSTEM (ENGINE DOES NOT START) Click here

CHECK VEHICLE CONDITION

Check the vehicle condition.

Result	Proceed to
w/ ID Code Box	A
w/o ID Code Box	B

CHECK HARNESS AND CONNECTOR Click here

CHECK HARNESS AND CONNECTOR

Disconnect the A30 ID code box (immobiliser code ECU) connector.
Disconnect the A35 ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A30-4 (IMO1) - A35-25 (IMO)	Always	Below 1 Ω
A30-4 (IMO1) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM
1. Temporarily replace the ECM with a new one Click here.
NEXT
REGISTER ECU COMMUNICATION ID
1. Register the ECU communication ID (Refer to Service Bulletin).
2. Check that the engine can be started.
  
  OK
  
  The engine can be started.
OK
END (ECM WAS DEFECTIVE)

NG
ID CODE BOX (IMMOBILIZER CODE ECU)

OK
The engine can be started.

CHECK HARNESS AND CONNECTOR

Disconnect the D48 certification ECU (smart key ECU assembly) connector.
Disconnect the A35 ECM connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
D48-13 (EGIO) - A35-25 (IMO1)	Always	Below 1 Ω
D48-13 (EGIO) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM
1. Temporarily replace the ECM with a new one Click here.
NEXT
REGISTER ECU COMMUNICATION ID
1. Register the ECU communication ID (Refer to Service Bulletin).
2. Check that the engine can be started.
  
  OK
  
  The engine can be started.
OK
END (ECM WAS DEFECTIVE)

NG
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)