Home

Toyota Workshop

GSIC - Global Service Information Center

DTC    U1002    Lost Communication with Gateway Module (Parking Assist Bus)

for Preparation Click here


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 parking assist bus.

DTC No.
DTC Detection Condition
Trouble Area
U1002
Driving support ECU cannot receive signals from all ECUs that have been memorized as those connected to the parking assist bus.
  1. Open or short in parking assist bus main wire or connector
  2. Open or short in parking assist bus branch wire or connector
  3. Driving support ECU
  4. CAN No. 5 junction connector

HINT:
The diagnosis procedure is for when DTC U1002 is output by the driving support ECU (Intelligent tester display: Pre-Crash2).


WIRING DIAGRAM


C211271E01


INSPECTION PROCEDURE

NOTICE:
  1. Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
  2. Turn the power switch off before inspecting CAN bus wires for a ground short.
  3. After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
  4. 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:
  1. 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.
  2. 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.

1.CHECK CAN BUS WIRE

  1. Turn the power switch off.



    E165597E12

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Result
    L60-40 (CA1P) - L60-18 (CA1N)
    		Power switch off
    		54 to 69 Ω
    		Below 54 Ω:
    Short circuit between bus lines
    70 Ω or more:
    Open circuit in a main bus line
    L60-40 (CA1P) - L60-25 (GND)
    		Power switch off
    		200 Ω or higher
    		Below 200 Ω:
    CANH ground short
    L60-18 (CA1N) - L60-25 (GND)
    		Power switch off
    		200 Ω or higher
    		Below 200 Ω:
    CANL ground short

    Text in Illustration 
    *1
    		Component with harness connected
    (Driving Support ECU)

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

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    		Result
    L60-40 (CA1P) - L60-30 (B)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Below 6 kΩ:
    CANH +B short
    L60-18 (CA1N) - L60-30 (B)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Below 6 kΩ:
    CANL +B short

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



B
Go to step 3

C
Go to step 6
A


2.CHECK CAN BUS BRANCH WIRE (MILLIMETER WAVE RADAR SENSOR)

  1. Check for a millimeter wave radar sensor communication malfunction (Click here).



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE DRIVING SUPPORT ECU (Click here)  

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


    E178930E21

  1. Disconnect the driving support ECU connector.
    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Driving Support ECU)

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    L60-40 (CA1P) - L60-18 (CA1N)
    		Power switch off
    		108 to 132 Ω



NG
Go to step 4
OK

REPLACE DRIVING SUPPORT ECU (Click here)  

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

  1. Reconnect the driving support ECU connector.



    C210458E01

  1. Disconnect the millimeter wave radar sensor connector.
    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Millimeter Wave Radar Sensor)

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A2-4 (CA1P) - A1-3 (CA1N)
    		Power switch off
    		108 to 132 Ω



NG
Go to step 5
OK

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY (Click here)  

5.CHECK FOR OPEN IN CAN BUS WIRE (CAN NO. 5 J/C)

  1. Reconnect the millimeter wave radar sensor connector.



    C210276E24

  1. Disconnect the CAN No. 5 junction connector.
    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to CAN No. 5 Junction Connector)
    *2
    		to Millimeter Wave Radar Sensor
    *3
    		to Driving Support ECU

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Connected to
    L102-1 (CANH) - L102-12 (CANL)
    		Power switch off
    		108 to 132 Ω
    		Millimeter wave radar sensor
    L102-3 (CANH) - L102-14 (CANL)
    		Power switch off
    		108 to 132 Ω
    		Driving support ECU

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (to driving support ECU)
    		B
    NG (to millimeter wave radar sensor)
    		C



B
REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - DRIVING SUPPORT ECU)

C
REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - MILLIMETER WAVE RADAR SENSOR)
A

REPLACE CAN NO. 5 JUNCTION CONNECTOR 

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

  1. Disconnect the driving support ECU connector.



    E178930E30

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Purpose
    L60-40 (CA1P) - L60-25 (GND)
    		Power switch off
    		200 Ω or higher
    		Below 200 Ω:
    CANH ground short
    L60-18 (CA1N) - L60-25 (GND)
    		Power switch off
    		200 Ω or higher
    		Below 200 Ω:
    CANL ground short
    L60-40 (CA1P) - L60-30 (B)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Below 6 kΩ:
    CANH +B short
    L60-18 (CA1N) - L60-30 (B)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Below 6 kΩ:
    CANL +B short

    HINT:
    1. 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.
      Find the necessary inspection from the Purpose column that matches the result in the Result column from the Check CAN Bus Wire inspection.
    2. If the resistance changes to normal when the connector is disconnected from the ECU, there may be a short in the ECU.

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Driving Support ECU)



NG
Go to step 7
OK

REPLACE DRIVING SUPPORT ECU (Click here)  

7.CHECK CAN BUS WIRE (MILLIMETER WAVE RADAR SENSOR)

  1. Disconnect the millimeter wave radar sensor connector.



    C210460E01

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Purpose
    A2-4 (CA1P) - L61-4 (CG)
    		Power switch off
    		200 Ω or higher
    		Below 200 Ω:
    CANH ground short
    A2-3 (CA1N) - L61-4 (CG)
    		Power switch off
    		200 Ω or higher
    		Below 200 Ω:
    CANL ground short
    A2-4 (CA1P) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Below 6 kΩ:
    CANH +B short
    A2-3 (CA1N) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Below 6 kΩ:
    CANL +B short

    HINT:
    1. 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.
      Find the necessary inspection from the Purpose column that matches the result in the Result column from the Check CAN Bus Wire inspection.
    2. If the resistance changes to normal when the connector is disconnected from the ECU, there may be a short in the ECU.

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to Millimeter Wave Radar Sensor)
    *2
    		DLC3



NG
Go to step 8
OK

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY (Click here)  

8.CHECK CAN BUS WIRE (CAN NO. 5 J/C)

  1. Disconnect the CAN No. 5 junction connector.



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


    C210570E15


    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    		Purpose
    		Connected to
    L102-1 (CANH) - L61-4 (CG)
    		Power switch off
    		200 Ω or higher
    		Inspection for CANH ground short
    		Millimeter wave radar sensor
    L102-12 (CANL) - L61-4 (CG)
    		Power switch off
    		200 Ω or higher
    		Inspection for CANL ground short
    L102-3 (CANH) - L61-4 (CG)
    		Power switch off
    		200 Ω or higher
    		Inspection for CANH ground short
    		Driving support ECU
    L102-14 (CANL) - L61-4 (CG)
    		Power switch off
    		200 Ω or higher
    		Inspection for CANL ground short
    L102-1 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Inspection for CANH +B short
    		Millimeter wave radar sensor
    L102-12 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Inspection for CANL +B short
    L102-3 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Inspection for CANH +B short
    		Driving support ECU
    L102-14 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Inspection for CANL +B short

    HINT:
    1. 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.
    2. Find the necessary inspection from the Purpose column that matches the result in the Result column from the Check CAN Bus Wire inspection.


    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to CAN No. 5 Junction Connector)
    		*2
    		DLC3
    *3
    		to Millimeter Wave Radar Sensor
    		*4
    		to Driving Support ECU

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (to driving support ECU)
    		B
    NG (to millimeter wave radar sensor)
    		C



B
REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - DRIVING SUPPORT ECU)

C
REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 5 J/C - MILLIMETER WAVE RADAR SENSOR)
A

REPLACE CAN NO. 5 JUNCTION CONNECTOR