PRE-COLLISION SYSTEM, Diagnostic DTC:U1002

DTC Code	DTC Name
U1002	Lost Communication with Gateway Module

DESCRIPTION

This DTC is stored when the driving support ECU assembly cannot receive signals from the forward recognition camera or millimeter wave radar sensor assembly.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
U1002	Lost Communication with Gateway Module	After the power switch is turned on, communication between the driving support ECU assembly and any of the following components is abnormal for 2 seconds or more Forward recognition camera Millimeter wave radar sensor assembly	CAN bus main line, CAN bus branch line or connector Forward recognition camera Millimeter wave radar sensor assembly Driving support ECU assembly No. 21 CAN junction connector

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

U1002

Lost Communication with Gateway Module

After the power switch is turned on, communication between the driving support ECU assembly and any of the following components is abnormal for 2 seconds or more

Forward recognition camera
Millimeter wave radar sensor assembly

CAN bus main line, CAN bus branch line or connector
Forward recognition camera
Millimeter wave radar sensor assembly
Driving support ECU assembly
No. 21 CAN junction connector

WIRING DIAGRAM


*a	Millimeter Wave Radar Sensor Assembly
*b	Driving Support ECU Assembly
*c	Forward Recognition Camera
*d	No. 21 CAN Junction Connector

CAUTION / NOTICE / HINT

Note

Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

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When replacing the millimeter wave radar sensor assembly, always replace it with a new one. If a millimeter wave radar sensor assembly which was installed to another vehicle is used, the information stored in the millimeter wave radar sensor assembly will not match the information from the vehicle. As a result, a DTC may be stored.
When the millimeter wave radar sensor assembly is replaced with a new one, adjustment of the radar sensor beam axis must be performed.

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When replacing the forward recognition camera, always replace it with a new one. If a forward recognition camera which was installed to another vehicle is used, the information stored in the forward recognition camera will not match the information from the vehicle. As a result, a DTC may be stored.
If the forward recognition camera has been replaced with a new one, be sure to perform forward recognition camera adjustment.

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Tech Tips

Operating the power switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE

CHECK CAN BUS LINE (MALFUNCTION CONFIRMATION)

Turn the power switch off.
Disconnect the cable from the negative (-) auxiliary battery terminal.

*a	Component with harness connected (Driving Support ECU Assembly)

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Result
M2-8 (CA1P) - M2-9 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω	Below 54 Ω: Short circuit between bus lines
M2-8 (CA1P) - M2-9 (CA1N)		54 to 69 Ω	70 Ω or more: Open circuit in a main bus line or driving support ECU assembly branch line
M2-8 (CA1P) - M2-28 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
M2-9 (CA1N) - M2-28 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
M2-8 (CA1P) - M2-7 (B)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
M2-9 (CA1N) - M2-7 (B)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short

Result

Result	Proceed to
OK	A
NG (Open circuit in main line or Driving support ECU assembly branch line)	B
NG (Short circuit between main lines)	C
NG (Short to +B or ground)	D

CHECK FOR OPEN IN CAN BUS BRANCH LINES (DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR SHORT BETWEEN CAN BUS LINES (FORWARD RECOGNITION CAMERA) Click here

CHECK FOR SHORT IN CAN BUS LINE (FORWARD RECOGNITION CAMERA) Click here

CHECK FOR DTCs (PRE-COLLISION SYSTEM)

Clear the DTCs.

Click here

Body Electrical > Pre-Collision 2 > Clear DTCs
Perform the following procedure.
Tech Tips

If the following procedure is not performed, the previously output DTC cannot be detected.
1. Turn the power switch on (IG) and wait 2 seconds or more.

Check for DTCs.

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Body Electrical > Pre-Collision 2 > Trouble Codes

Result

Result	Proceed to
DTC U1002 is not output	A
DTC U1002 is output	B

USE SIMULATION METHOD TO CHECK Click here

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

CHECK FOR OPEN IN CAN BUS BRANCH LINES (DRIVING SUPPORT ECU ASSEMBLY)

*a
Front view of wire harness connector

(to Driving Support ECU Assembly)

Disconnect the M2 driving support ECU assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
M2-8 (CA1P) - M2-9 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Tech Tips

If the resistance is between 108 and 132 Ω, there may be an open in a CAN bus main line. If the value is 132 Ω or more, there may be an open in a CAN bus branch line between the No. 21 CAN junction connector and the driving support ECU or a connector may be disconnected.

Connect the M2 driving support ECU assembly connector.

Result

Proceed to
OK
NG

CHECK FOR OPEN IN CAN BUS BRANCH LINES (NO. 21 CAN JUNCTION CONNECTOR - DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR OPEN IN CAN BUS MAIN LINES (NO. 21 CAN JUNCTION CONNECTOR)

*a
Front view of wire harness connector

(to No. 21 CAN Junction Connector)

Disconnect the K156 No. 21 CAN junction connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K156-7 (CANH) - K156-18 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Forward Recognition Camera
K156-5 (CA1P) - K156-16 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Millimeter Wave Radar Sensor Assembly

Connect the K156 No. 21 CAN junction connector.

Result

Result	Proceed to
OK	A
NG (Forward Recognition Camera Main Line)	B
NG (Millimeter Wave Radar Sensor Assembly Main Line)	C

REPLACE NO. 21 CAN JUNCTION CONNECTOR

CHECK FOR OPEN IN CAN BUS MAIN LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) Click here

CHECK FOR OPEN IN CAN BUS MAIN LINES (FORWARD RECOGNITION CAMERA)

*a
Front view of wire harness connector

(to Forward Recognition Camera)

Disconnect the S18 forward recognition camera connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
S18-6 (CANH) - S18-12 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Connect the S18 forward recognition camera connector.

Result

Proceed to
OK
NG

REPLACE FORWARD RECOGNITION CAMERA Click here

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - FORWARD RECOGNITION CAMERA)

CHECK FOR OPEN IN CAN BUS MAIN LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

*a
Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)

Disconnect the B12 millimeter wave radar sensor assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
B12-5 (CA1P) - B12-6 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Connect the B12 millimeter wave radar sensor assembly connector.

Result

Proceed to
OK
NG

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

CHECK FOR OPEN IN CAN BUS BRANCH LINES (NO. 21 CAN JUNCTION CONNECTOR - DRIVING SUPPORT ECU ASSEMBLY)

*a
Front view of wire harness connector

(to Driving Support ECU Assembly)

Disconnect the M2 driving support ECU assembly connector.
*a
Front view of wire harness connector

(to No. 21 CAN Junction Connector)

Disconnect the K156 No. 21 CAN junction connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
K156-6 (CA1P) - M2-8 (CA1P)	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω
K156-17 (CA1N) - M2-9 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

Connect the K156 No. 21 CAN junction connector.

Connect the M2 driving support ECU assembly connector.

Result

Proceed to
OK
NG

REPLACE NO. 21 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN BUS BRANCH WIRE (NO. 21 CAN JUNCTION CONNECTOR - DRIVING SUPPORT ECU ASSEMBLY)

CHECK FOR SHORT BETWEEN CAN BUS LINES (FORWARD RECOGNITION CAMERA)

*a
Front view of wire harness connector

(to Forward Recognition Camera)

Disconnect the S18 forward recognition camera connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
S18-6 (CANH) - S18-12 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Connect the S18 forward recognition camera connector.

Result

Proceed to
OK
NG

REPLACE FORWARD RECOGNITION CAMERA Click here

CHECK FOR SHORT BETWEEN CAN BUS LINES (NO. 21 CAN JUNCTION CONNECTOR)

*a	Front view of wire harness connector (to No. 21 CAN Junction Connector)
*b	to Forward Recognition Camera
*c	to Millimeter Wave Radar Sensor Assembly
*d	to Driving Support ECU Assembly

Disconnect the K156 No. 21 CAN junction connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K156-7 (CANH) - K156-18 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Forward Recognition Camera
K156-5 (CA1P) - K156-16 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω	Millimeter Wave Radar Sensor Assembly
K156-6 (CA1P) - K156-17 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Driving Support ECU Assembly

Connect the K156 No. 21 CAN junction connector.

Result

Result	Proceed to
OK	A
NG (Forward Recognition Camera Main Line)	B
NG (Millimeter Wave Radar Sensor Assembly Main Line)	C
NG (Driving Support ECU Assembly Branch Line)	D

REPLACE NO. 21 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - FORWARD RECOGNITION CAMERA)

CHECK FOR SHORT BETWEEN CAN BUS LINES (DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR SHORT BETWEEN CAN BUS LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

*a
Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)

Disconnect the B12 millimeter wave radar sensor assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
B12-5 (CA1P) - B12-6 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

Connect the B12 millimeter wave radar sensor assembly connector.

Result

Proceed to
OK
NG

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

CHECK FOR SHORT BETWEEN CAN BUS LINES (DRIVING SUPPORT ECU ASSEMBLY)

*a
Front view of wire harness connector

(to Driving Support ECU Assembly)

Disconnect the M2 driving support ECU assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
M2-8 (CA1P) - M2-9 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

Connect the M2 driving support ECU assembly connector.

Result

Proceed to
OK
NG

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

REPAIR OR REPLACE CAN BUS BRANCH LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - DRIVING SUPPORT ECU ASSEMBLY)

CHECK FOR SHORT IN CAN BUS LINE (FORWARD RECOGNITION CAMERA)

Disconnect the S18 forward recognition camera connector.

DLC3

Front view of wire harness connector

(to Forward Recognition Camera)

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

Standard Resistance

Tester Connection	Condition	Specified Condition
S18-6 (CANH) - K9-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher
S18-12 (CANL) - K9-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher
S18-6 (CANH) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher
S18-12 (CANL) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher

Connect the S18 forward recognition camera connector.

Result

Proceed to
OK
NG

REPLACE FORWARD RECOGNITION CAMERA Click here

CHECK FOR SHORT IN CAN BUS LINE (NO. 21 CAN JUNCTION CONNECTOR)

Disconnect the K156 No. 21 CAN junction connector.

DLC3

Front view of wire harness connector

(to No. 21 CAN Junction Connector)

to Forward Recognition Camera

to Millimeter Wave Radar Sensor Assembly

to Driving Support ECU Assembly

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
K156-7 (CANH) - K9-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Forward Recognition Camera
K156-18 (CANL) - K9-4 (CG)		200 Ω or higher
K156-7 (CANH) - K9-16 (BAT)		6 kΩ or higher
K156-18 (CANL) - K9-16 (BAT)		6 kΩ or higher
K156-5 (CA1P) - K9-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Millimeter Wave Radar Sensor Assembly
K156-16 (CA1N) - K9-4 (CG)		200 Ω or higher
K156-5 (CA1P) - K9-16 (BAT)		6 kΩ or higher
K156-16 (CA1N) - K9-16 (BAT)		6 kΩ or higher
K156-6 (CA1P) - K9-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Driving Support ECU Assembly
K156-17 (CA1N) - K9-4 (CG)		200 Ω or higher
K156-6 (CA1P) - K9-16 (BAT)		6 kΩ or higher
K156-17 (CA1N) - K9-16 (BAT)		6 kΩ or higher

Connect the K156 No. 21 CAN junction connector.

Result

Result	Proceed to
OK	A
NG (Forward Recognition Camera Main Line)	B
NG (Millimeter Wave Radar Sensor Assembly Main Line)	C
NG (Driving Support ECU Assembly Branch Line)	D

REPLACE NO. 21 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - FORWARD RECOGNITION CAMERA)

CHECK FOR SHORT IN CAN BUS LINE (DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR SHORT IN CAN BUS LINE (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

Disconnect the B12 millimeter wave radar sensor assembly connector.

DLC3

Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)

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

Standard Resistance

Tester Connection	Condition	Specified Condition
B12-5 (CA1P) - K9-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher
B12-6 (CA1N) - K9-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher
B12-5 (CA1P) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher
B12-6 (CA1N) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher

Connect the B12 millimeter wave radar sensor assembly connector.

Result

Proceed to
OK
NG

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

CHECK FOR SHORT IN CAN BUS LINE (DRIVING SUPPORT ECU ASSEMBLY)

Disconnect the M2 driving support ECU assembly connector.

DLC3

Front view of wire harness connector

(to Driving Support ECU Assembly)

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

Standard Resistance

Tester Connection	Condition	Specified Condition
M2-8 (CA1P) - K9-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher
M2-9 (CA1N) - K9-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher
M2-8 (CA1P) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher
M2-9 (CA1N) - K9-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher

Connect the M2 driving support ECU assembly connector.

Result

Proceed to
OK
NG

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

REPAIR OR REPLACE CAN BUS BRANCH LINE OR CONNECTOR (NO. 21 CAN JUNCTION CONNECTOR - DRIVING SUPPORT ECU ASSEMBLY)