CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU), Diagnostic DTC:U1002, U0235

DTC Code	DTC Name
U1002	Lost Communication with Gateway Module (Sensor Bus)
U0235	Lost Communication with Cruise Control Front Distance Range Sensor

DESCRIPTION

The driving support ECU assembly will store this DTC when no signals can be received from the ECUs that have been memorized as those that are connected to sub bus 13.
When the driving support ECU assembly receives a response signal from the ECUs connected to sub bus 13, the driving support ECU assembly recognizes and memorizes that the ECU is connected to sub bus 13. Based on this memorized data, the driving support ECU assembly monitors for malfunctions in the ECUs connected to sub bus 13 when communicating with those ECUs. If the driving support ECU assembly cannot receive response signals from the ECUs that have been memorized as those connected to sub bus 13, the driving support ECU assembly determines that a malfunction exists.

DTC No.	DTC Detection Condition	Trouble Area
U0235	No communication from the millimeter wave radar sensor assembly continues.	Open or short in sub bus 13 main line or connector Millimeter wave radar sensor assembly Power source circuit of millimeter wave radar sensor assembly Millimeter wave radar sensor assembly ground circuit
U1002	The driving support ECU assembly cannot receive signals from all ECUs that have been memorized as those connected to the sensor bus 13.	Open or short in sub bus 13 main line or connector Driving support ECU assembly Power source circuit of driving support ECU assembly Driving support ECU assembly ground circuit Millimeter wave radar sensor assembly Power source circuit of millimeter wave radar sensor assembly Millimeter wave radar sensor assembly ground circuit

Tech Tips

The diagnosis procedure is for when DTC U1002 is output by the driving support ECU assembly (GTS display: Pre-crash 2).

WIRING DIAGRAM

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 Click here.
Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output Click here.
After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.

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

CONFIRM RECONFIRM DTC OUTPUT

Reconfirm DTCs.

Result

Result	Proceed to
DTC U0104 is not output from the power management control ECU (GTS display: PM1 Gateway)	A
DTC U0104 is output from the power management control ECU (GTS display: PM1 Gateway)	B

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

CHECK SUB BUS 13

Disconnect the cable from the negative (-) auxiliary battery terminal.

Text in Illustration
*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
L60-40 (CA1P) - L60-18 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω	Below 54 Ω: Short circuit between bus lines
L60-40 (CA1P) - L60-18 (CA1N)		54 to 69 Ω	70 Ω or more: Open circuit in main bus lines
L60-40 (CA1P) - L60-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
L60-18 (CA1N) - L60-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANL ground short
L60-40 (CA1P) - L60-30 (B)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
L60-18 (CA1N) - L60-30 (B)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

Result

Result	Proceed to
OK	A
NG (Open circuit in CAN main bus line)	B
NG (Short circuit between bus lines)	C
NG (Ground short) NG (+B short)	D

CHECK FOR OPEN IN SUB BUS 13 MAIN LINES (DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR SHORT IN SUB BUS 13 LINES (DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR SHORT IN SUB BUS 13 LINE (DRIVING SUPPORT ECU ASSEMBLY) Click here

CHECK FOR POWER SOURCE CIRCUIT (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)
1. Check the millimeter wave radar sensor assembly power source circuit Click here.
NG
REPAIR OR REPLACE POWER SOURCE CIRCUIT (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

OK

CHECK FOR DTC OUTPUT

Reconnect the cable to the negative (-) auxiliary battery terminal.
Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Clear the DTCs.
Turn the power switch off.
Turn the power switch on (IG).

Check for DTCs.

Result

Result	Proceed to
DTC U1002 is not output from the driving support ECU assembly (GTS display: Pre-Crash 2)	A
DTC U1002 is output from the driving support ECU assembly (GTS display: Pre-Crash 2)	B

SYMPTOM SIMULATION Click here

REPLACE DRIVING SUPPORT ECU ASSEMBLY
1. Replace the driving support ECU assembly. Click here
NEXT

CHECK FOR DTC OUTPUT

Reconnect the cable to the negative (-) auxiliary battery terminal.
Turn the power switch off.
Turn the power switch on (IG).

Check for DTCs.

Result

Result	Proceed to
DTC U1002 is not output from the driving support ECU assembly (GTS display: Pre-Crash 2)	A
DTC U1002 is output from the driving support ECU assembly (GTS display: Pre-Crash 2)	B

END

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

CHECK FOR OPEN IN SUB BUS 13 MAIN LINES (DRIVING SUPPORT ECU ASSEMBLY)

Text in Illustration

*a
Front view of wire harness connector

(to Driving Support ECU Assembly)

Disconnect the L60 driving support ECU assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
L60-40 (CA1P) - L60-18 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

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

Reconnect the L60 driving support ECU assembly connector.
Text in Illustration

*a
Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)

Disconnect the A76 millimeter wave radar sensor assembly connector.

Text in Illustration
*a	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
A76-3 (CA1P) - A76-2 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR

CHECK FOR SHORT IN SUB BUS 13 LINES (DRIVING SUPPORT ECU ASSEMBLY)

Text in Illustration

*a
Front view of wire harness connector

(to Driving Support ECU Assembly)

Disconnect the L60 driving support ECU assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
L60-40 (CA1P) - L60-18 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

CHECK FOR SHORT IN SUB BUS 13 LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

Reconnect the L60 driving support ECU assembly connector.
Text in Illustration

*a
Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)

Disconnect the A76 millimeter wave radar sensor assembly connector.

Text in Illustration
*a	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
A76-3 (CA1P) - A76-2 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR

CHECK FOR SHORT IN SUB BUS 13 LINE (DRIVING SUPPORT ECU ASSEMBLY)

Disconnect the L60 driving support ECU assembly connector.

Text in Illustration
*a	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	Result
L60-40 (CA1P) - L60-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
L60-18 (CA1N) - L60-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANL ground short
L60-40 (CA1P) - L60-30 (B)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
L60-18 (CA1N) - L60-30 (B)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

Tech Tips

It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check Sensor Bus Lines inspection.
Find the necessary inspection from the Result column that matches the result in the Result column from the Check Sensor Bus Lines inspection.

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

CHECK FOR SHORT IN SUB BUS 13 LINE (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

Reconnect the L60 driving support ECU assembly connector.

Text in Illustration
*1	DLC3
*a	Front view of wire harness connector (to Millimeter Wave Radar Sensor Assembly)

Disconnect the A76 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	Result
A76-3 (CA1P) - L61-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
A76-2 (CA1N) - L61-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANL ground short
A76-3 (CA1P) - L61-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
A76-2 (CA1N) - L61-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

Tech Tips

It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check Sub Bus 13 inspection.
Find the necessary inspection from the Result column that matches the result in the Result column from the Check Sub Bus 13 inspection.

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR