This DTC is stored when there is an open or short circuit in the communication line between the front sensors and the ECU, or when there is a malfunction in a front sensor.

DTC Code	DTC Detection Condition	Trouble Area
C1AEC	An open or short circuit in the communication line between the front sensors and ECU or a malfunction in a front sensor during initialization mode after the engine switch is turned on (IG).	No. 1 ultrasonic sensor (front side) Harness or connector Parking assist ECU1 Clearance warning ECU assembly2

*1: w/ Side Monitor System

*2: w/o Side Monitor System

WIRING DIAGRAM

Dtc C1Aec Front Sensor Communication Malfunction. PARK ASSIST / MONITORING. Land Cruiser URJ200 URJ202 GRJ200 VDJ200

INSPECTION PROCEDURE

1.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

Result
Result	Proceed to
DTC C1AEC is output (w/ Side Monitor System)	A
DTC C1AEC is output (w/o Side Monitor System)	B
DTC C1AEC is not output	C

Go to step 10

USE SIMULATION METHOD TO CHECK ()

A

2.CHECK HARNESS AND CONNECTOR (NO. 1 ULTRASONIC SENSOR [FL SENSOR] - PARKING ASSIST ECU)

Disconnect the B8 No. 1 ultrasonic sensor (FL sensor) connector.

Disconnect the F76 parking assist ECU connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
B8-1 (BI) - F76-5 (CSB1)	Always	Below 1 Ω
B8-3 (SI) - F76-23 (LIN1)	Always	Below 1 Ω
B8-5 (EI) - F76-6 (CSG1)	Always	Below 1 Ω
B8-1 (BI) - Body ground	Always	10 kΩ or higher
B8-3 (SI) - Body ground	Always	10 kΩ or higher
B8-5 (EI) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.CHECK HARNESS AND CONNECTOR (NO. 1 ULTRASONIC SENSOR [FL SENSOR] - NO. 1 ULTRASONIC SENSOR [FR SENSOR])

Disconnect the B8 No. 1 ultrasonic sensor (FL sensor) connector.

Disconnect the B7 No. 1 ultrasonic sensor (FR sensor) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
B8-2 (BO) - B7-1 (BI)	Always	Below 1 Ω
B8-4 (SO) - B7-3 (SI)	Always	Below 1 Ω
B8-6 (EO) - B7-5 (EI)	Always	Below 1 Ω
B8-2 (BO) - Body ground	Always	10 kΩ or higher
B8-4 (SO) - Body ground	Always	10 kΩ or higher
B8-6 (EO) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.CHECK PARKING ASSIST ECU

Dtc C1Aec Front Sensor Communication Malfunction. PARK ASSIST / MONITORING. Land Cruiser URJ200 URJ202 GRJ200 VDJ200

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

Standard Voltage:
Tester Connection Switch Condition Specified Condition
F76-5 (CSB1) - Body ground Engine switch on (IG) 7.2 to 8.8 V

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

Standard Resistance:
Tester Connection Condition Specified Condition
F76-6 (CSG1) - Body ground Always Below 1 Ω

Text in Illustration
*a	Component with harness connected (Parking Assist ECU)

REPLACE PARKING ASSIST ECU ()

OK

5.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

OK:
DTC C1AEC is not output.

Go to step 6

USE SIMULATION METHOD TO CHECK ()

6.REPLACE NO. 1 ULTRASONIC SENSOR (FL SENSOR)

Replace the No. 1 ultrasonic sensor (FL sensor) with a normally functioning one ().

NEXT

7.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

OK:
DTC C1AEC is not output.

Go to step 8

END (NO. 1 ULTRASONIC SENSOR [FL SENSOR] IS DEFECTIVE)

8.REPLACE NO. 1 ULTRASONIC SENSOR (FR SENSOR)

Replace the No. 1 ultrasonic sensor (FR sensor) with a normally functioning one ()

NEXT

9.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

OK:
DTC C1AEC is not output.

REPLACE PARKING ASSIST ECU ()

END (NO. 1 ULTRASONIC SENSOR [FR SENSOR] IS DEFECTIVE)

10.CHECK HARNESS AND CONNECTOR (NO. 1 ULTRASONIC SENSOR [FL SENSOR] - CLEARANCE WARNING ECU ASSEMBLY)

Disconnect the B8 No. 1 ultrasonic sensor [FL sensor] connector.

Disconnect the F12 clearance warning ECU assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
B8-1 (BI) - F12-21 (CSB1)	Always	Below 1 Ω
B8-3 (SI) - F12-9 (LIN1)	Always	Below 1 Ω
B8-5 (EI) - F12-19 (CSG1)	Always	Below 1 Ω
B8-1 (BI) - Body ground	Always	10 kΩ or higher
B8-3 (SI) - Body ground	Always	10 kΩ or higher
B8-5 (EI) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

11.CHECK HARNESS AND CONNECTOR (NO. 1 ULTRASONIC SENSOR [FL SENSOR] - NO. 1 ULTRASONIC SENSOR [FR SENSOR])

Disconnect the B8 No. 1 ultrasonic sensor (FL sensor) connector.

Disconnect the B7 No. 1 ultrasonic sensor (FR sensor) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
B8-2 (BO) - B7-1 (BI)	Always	Below 1 Ω
B8-4 (SO) - B7-3 (SI)	Always	Below 1 Ω
B8-6 (EO) - B7-5 (EI)	Always	Below 1 Ω
B8-2 (BO) - Body ground	Always	10 kΩ or higher
B8-4 (SO) - Body ground	Always	10 kΩ or higher
B8-6 (EO) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

12.CHECK CLEARANCE WARNING ECU ASSEMBLY

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

Standard Voltage:
Tester Connection Switch Condition Specified Condition
F12-21 (CSB1) - Body ground Engine switch on (IG) 7.2 to 8.8 V

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

Standard Resistance:
Tester Connection Condition Specified Condition
F12-19 (CSG1) - Body ground Always Below 1 Ω

Text in Illustration
*a	Component with harness connected (Clearance Warning ECU Assembly)

REPLACE CLEARANCE WARNING ECU ASSEMBLY ()

OK

13.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

OK:
DTC C1AEC is not output.

Go to step 4

USE SIMULATION METHOD TO CHECK ()

14.REPLACE NO. 1 ULTRASONIC SENSOR (FL SENSOR)

Replace the No. 1 ultrasonic sensor (FL sensor) with a normally functioning one ().

NEXT

15.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

OK:
DTC C1AEC is not output.

Go to step 16

END (NO. 1 ULTRASONIC SENSOR [FL SENSOR] IS DEFECTIVE)

16.REPLACE NO. 1 ULTRASONIC SENSOR (FR SENSOR)

Replace the No. 1 ultrasonic sensor (FR sensor) with a normally functioning one ().

NEXT

17.CHECK FOR DTC

Clear the DTCs ().

Check for DTCs ().

OK:
DTC C1AEC is not output.

REPLACE CLEARANCE WARNING ECU ASSEMBLY ()

END (NO. 1 ULTRASONIC SENSOR [FR SENSOR] IS DEFECTIVE)

PARK ASSIST / MONITORING

Land Cruiser URJ200 URJ202 GRJ200 VDJ200

TOYOTA PARKING ASSIST-SENSOR SYSTEM

Tester Connection	Switch Condition	Specified Condition
F76-5 (CSB1) - Body ground	Engine switch on (IG)	7.2 to 8.8 V