CAN Communication System - Lost Communication with Gateway Module (Pre-Collision2)

NETWORKING: CAN COMMUNICATION SYSTEM: U1002: Lost Communication with Gateway Module (Pre-Collision2)
U1002 - Lost Communication with Gateway Module (Pre-Collision2)

DESCRIPTION

The driving support ECU will store this DTC when no signals can be received from the ECUs that have been memorized as those that are connected to the driving support bus.

HINT
The diagnosis procedure is for when DTC U1002 is output by the driving support ECU (Techstream display: Pre-Collision2).

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
* 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.

HINT
* 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

1. CHECK CAN BUS WIRE

(a) Turn the power switch off.

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

Standard Resistance:

Text in Illustration

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

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

Standard Resistance:

Result:

B -- CHECK DTC OUTPUT (DYNAMIC RADAR CRUISE CONTROL SYSTEM)

C -- CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU)

D -- CHECK FOR SHORT IN CAN BUS WIRES (DRIVING SUPPORT ECU)

E -- CHECK CAN BUS WIRE (CAN NO. 4 J/C)
A -- Continue to next step.

2. CHECK CAN BUS BRANCH WIRE

(a) for vehicle with lane-keeping assist system:

(1) Check for a lane recognition camera sensor communication malfunction Lane-Keeping Assist System.

(b) for vehicle with driver monitor system:

(1) Check for a driver monitor ECU branch wire and ECU power source circuit U1121.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

3. CHECK DTC OUTPUT (DYNAMIC RADAR CRUISE CONTROL SYSTEM)

(a) Check the dynamic radar cruise control system DTCs Dynamic Radar Cruise Control System.

Result:

B -- GO TO CIRCUITS INDICATED BY OUTPUT DTCS

A -- REPLACE DRIVING SUPPORT ECU Removal

4. CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU)

(a) Disconnect the driving support ECU connector.

Text in Illustration

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

Standard Resistance:

NG -- CHECK FOR OPEN IN CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR)

OK -- REPLACE DRIVING SUPPORT ECU Removal

5. CHECK FOR OPEN IN CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR)

(a) Reconnect the driving support ECU connector.

(b) Disconnect the millimeter wave radar sensor connector.

Text in Illustration

NG -- CHECK FOR OPEN IN CAN BUS WIRE (CAN NO. 4 J/C)

OK -- REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Removal

6. CHECK FOR OPEN IN CAN BUS WIRE (CAN NO. 4 J/C)

(a) Reconnect the millimeter wave radar sensor connector.

(b) Disconnect the CAN No. 4 junction connector.

Text in Illustration

Result:

B -- REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 4 J/C - DRIVING SUPPORT ECU)

C -- REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 4 J/C - MILLIMETER WAVE RADAR SENSOR)

A -- REPLACE CAN NO. 4 JUNCTION CONNECTOR

7. CHECK FOR SHORT IN CAN BUS WIRES (DRIVING SUPPORT ECU)

(a) Disconnect the driving support ECU connector.

Text in Illustration

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

Standard Resistance:

NG -- CHECK FOR SHORT IN CAN BUS WIRES (MILLIMETER WAVE RADAR SENSOR)

OK -- REPLACE DRIVING SUPPORT ECU Removal

8. CHECK FOR SHORT IN CAN BUS WIRES (MILLIMETER WAVE RADAR SENSOR)

(a) Reconnect the driving support ECU connector.

(b) Disconnect the millimeter wave radar sensor connector.

Text in Illustration

NG -- CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 4 J/C)

OK -- REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY Removal

9. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 4 J/C)

(a) Reconnect the millimeter wave radar sensor connector.

(b) Disconnect the CAN No. 4 junction connector.

Text in Illustration

Result:

B -- CHECK FOR SHORT IN CAN BUS WIRES (LANE RECOGNITION CAMERA SENSOR BRANCH WIRE)

C -- REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 4 J/C - DRIVING SUPPORT ECU)

D -- REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 4 J/C - MILLIMETER WAVE RADAR SENSOR)

A -- REPLACE CAN NO. 4 JUNCTION CONNECTOR

10. CHECK FOR SHORT IN CAN BUS WIRES (LANE RECOGNITION CAMERA SENSOR BRANCH WIRE)

HINT
For vehicles without the lane-keeping assist system, go to the next step.

(a) Disconnect the lane recognition camera sensor connector.

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (LANE RECOGNITION CAMERA SENSOR)
OK -- Continue to next step.

11. CHECK FOR SHORT IN CAN BUS WIRES (DRIVER MONITOR ECU BRANCH WIRE)

HINT
For vehicles without the driver monitor system, go to the next step.

(a) Disconnect the driver monitor ECU connector.

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

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (DRIVER MONITOR ECU)
OK -- Continue to next step.

12. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 4 J/C)

(a) Reconnect the CAN No. 4 junction connector.

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

Standard Resistance:

Text in Illustration

NOTICE:
* The resistance must be measured after the CAN No. 4 junction connector is reconnected.
* The resistance must be measured after the driver monitor ECU and lane recognition camera sensor connector are disconnected.

NG -- REPLACE CAN NO. 4 JUNCTION CONNECTOR
OK -- Continue to next step.

13. CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR)

(a) Connect the probes of an ohmmeter to terminals 40 (CA1P) and 18 (CA1N) of the driving support ECU.

Text in Illustration

(b) While observing the resistance value shown the ohmmeter, reconnect driver monitor ECU or lane recognition camera sensor connector until the resistance becomes abnormal (Below 54 Ohms).

HINT
If the resistance becomes abnormal when an ECU (sensor) connector is reconnected, there may be short in the ECU (sensor)

NEXT -- REPLACE CORRESPONDING ECU OR SENSOR

14. CHECK CAN BUS WIRE (CAN NO. 4 J/C)

(a) Disconnect the CAN No. 4 junction connector.

Text in Illustration

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

Standard Resistance:

Inspection for CAN Ground Short

Inspection for CAN +B Short

HINT
It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN Bus Wire inspection.

NG -- CHECK CAN BUS WIRE (ECU, SENSOR)

OK -- REPLACE CAN NO. 4 JUNCTION CONNECTOR

15. CHECK CAN BUS WIRE (ECU, SENSOR)

(a) Disconnect the ECU or sensor connected to the CAN bus wire that is shorted to B+ or shorted to GND.

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

Standard Resistance:

Inspection for CAN Ground Short

Inspection for CAN +B Short

HINT
It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN Bus Wire inspection.

Text in Illustration

NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR WIRE OR CONNECTOR

OK -- REPLACE CORRESPONDING ECU OR SENSOR