CAN COMMUNICATION SYSTEM, 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 a DTC when no signals can be received from the millimeter wave radar sensor assembly.
When the driving support ECU assembly receives a response signal from the millimeter wave radar sensor assembly connected to the sensor bus, the driving support ECU assembly recognizes and memorizes the millimeter wave radar sensor assembly. Based on this memorized data, the driving support ECU assembly monitors for malfunctions in the millimeter wave radar sensor assembly when communicating with the millimeter wave radar sensor assembly. If the driving support ECU assembly cannot receive response signals from the millimeter wave radar sensor assembly that has been memorized as that connected to the sensor bus, the driving support ECU assembly determines that a malfunction exists.

DTC No.	DTC Detection Condition	Trouble Area
U1002	Lost Communication with Gateway Module (Sensor Bus).	Open or short in sensor bus main line or connector Driving support ECU assembly Millimeter wave radar sensor assembly Power source circuit of millimeter wave radar sensor assembly Millimeter wave radar sensor assembly ground circuit
U0235	Lost Communication with Cruise Control Front Distance Range Sensor	Open or short in sensor bus 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

WIRING DIAGRAM

INSPECTION PROCEDURE

Note

Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
Turn the power switch off before inspecting CAN bus wires for a ground short.
After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the power switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

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

RECONFIRM DTC OUTPUT

Reconfirm DTCs.

Result

Result	Proceed to
DTC U1104 not output from power management control ECU (intelligent tester display: PM1 Gateway)	A
DTC U1104 is output from power management control ECU (intelligent tester display: PM1 Gateway)	B

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

CHECK SENSOR BUS

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

Text in Illustration
*1	DLC3
*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
C1-40 (CA1P) - C1-18 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω	Below 54 Ω: Short circuit between bus lines
C1-40 (CA1P) - C1-18 (CA1N)		54 to 69 Ω	70 Ω or more: Open circuit in main bus line
C1-40 (CA1P) - C1-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
C1-18 (CA1N) - C1-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANL ground short
C1-40 (CA1P) - F17-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
C1-18 (CA1N) - F17-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

Result

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

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

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

CHECK FOR SHORT IN SENSOR BUS 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.
  
  OK
  
  The millimeter wave radar sensor assembly power source circuit is normal.
NG
REPAIR OR REPLACE POWER SOURCE CIRCUIT (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)

OK

OK
The millimeter wave radar sensor assembly power source circuit is normal.

CHECK FOR DTC OUTPUT

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the intelligent tester on.
Clear the DTCs.
Turn the power switch off.
Turn the power switch on (IG).

Check for DTCs.

Result

Result	Proceed to
DTC U1002 not output from driving support ECU assembly (intelligent tester display: Pre-crash2)	A
DTC U1002 is output from driving support ECU assembly (intelligent tester display: Pre-crash2)	B

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

SYMPTOM SIMULATION Click here

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

Disconnect the C1 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
C1-40 (CA1P) - C1-18 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

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

REPLACE DRIVING SUPPORT ECU ASSEMBLY 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).
Turn the intelligent tester on.

Check for DTCs.

Result

Result	Proceed to
DTC U1002 not output from driving support ECU assembly (intelligent tester display: Pre-crash2)	A
DTC U1002 is output from driving support ECU assembly (intelligent tester display: Pre-crash2)	B

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

END

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

Disconnect the C1 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
C1-40 (CA1P) - C1-18 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

CHECK FOR SHORT IN SENSOR BUS LINES (MILLIMETER WAVE RADAR SENSOR ASSEMBLY) Click here

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

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

Disconnect the C1 driving support ECU assembly connector.

Text in Illustration
*1	DLC3
*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	Purpose
C1-40 (CA1P) - C1-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
C1-18 (CA1N) - C1-25 (GND)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANL ground short
C1-40 (CA1P) - F17-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
C1-18 (CA1N) - F17-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

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

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

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

Reconnect the C1 driving support ECU assembly connector.
Disconnect the B1 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
B1-4 (CA1P) - B1-3 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

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

Reconnect the C1 driving support ECU assembly connector.
Disconnect the B1 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
B1-4 (CA1P) - B1-3 (CA1N)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here

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

Reconnect the C1 driving support ECU assembly connector.
Disconnect the B1 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	Purpose
B1-4 (CA1P) - F17-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANH ground short
B1-3 (CA1N) - F17-4 (CG)	Cable disconnected from negative (-) auxiliary battery terminal	200 Ω or higher	Below 200 Ω: CANL ground short
B1-4 (CA1P) - F17-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANH +B short
B1-3 (CA1N) - F17-16 (BAT)	Cable disconnected from negative (-) auxiliary battery terminal	6 kΩ or higher	Below 6 kΩ: CANL +B short

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

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Click here