How To Proceed With Troubleshooting

WARNING: This page is about a different car, the 2008 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0114, U0123, U0124, U0126, U0129, U0199, U0208, U1002, U1115, B1499, and B2621
Refer to the troubleshooting procedures of each system if DTCs regarding the CAN communication system are not output.
Before measuring the resistance, leave the vehicle for at least 1 minute and do not operate the ignition switch, any switches or doors. If doors need to be opened in order to check connectors, open the doors and leave them open.

HINT:

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.
*: Use the Techstream.

VEHICLE BROUGHT TO WORKSHOP
INSPECT BATTERY VOLTAGE
Standard voltage: 11 to 14 V

If the voltage is below 11V, recharge or replace the battery before proceeding.
CHECK AND CLEAR DTC*
1. Using the intelligent tester or Techstream, perform the ALL DTC check.
  NOTE:
  - If a CAN communication malfunction code that informs that an ECU or sensor has a power malfunction or interior malfunction is causing a communication stop, the problem may not be in the communication line. There is a high possibility that the ECU or sensor has a signal transmission failure. Therefore, first troubleshoot any DTCs related to the ECU or sensor.
  - When CAN communication related connectors are disconnected with the ignition switch ON or ACC, the ECU related to the connector and ECUs of related systems will store a CAN communication DTC.
CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION
1. Based on the vehicle equipment and specifications, confirm the systems that use CAN communication (see DIAGNOSIS SYSTEM ).

CHECK DLC3 BRANCH WIRE AND V BUS CIRCUIT MAIN WIRE (CANH - CANL)

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

Standard resistance

STANDARD RESISTANCE SPECIFICATION TABLE

Tester Connection	Switch Condition	Specified Condition	Proceed to
6 (CANH) - 14 (CANL)	Ignition switch OFF	OK (54 to 69 Ω)	A
		NG (70 Ω or higher)	B
		NG (less than 54 Ω)	C

Fig 1: Identifying Terminals CANH And CANL Of DLC3 Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

B: GO TO CAN MAIN WIRE FOR DISCONNECTION (See OPEN IN CAN MAIN WIRE )

C: GO TO CHECK CAN BUS LINES FOR SHORT CIRCUIT (See SHORT IN CAN BUS LINES )

A: Go to Next Step

CHECK V BUS CIRCUIT +B (CANH, CANL - BAT)

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

Standard resistance

STANDARD RESISTANCE SPECIFICATION TABLE

Tester Connection	Switch Condition	Specified Condition
6 (CANH) - 16 (BAT)	Ignition switch OFF	6 kΩ or higher
14 (CANL) - 16 (BAT)	Ignition switch OFF	6 kΩ or higher

Fig 2: Identifying DLC3 Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: GO TO CHECK CAN BUS LINE FOR SHORT TO +B (See SHORT TO B+ IN CAN BUS LINE )

OK: Go to Next Step

CHECK V BUS CIRCUIT GND (CANH, CANL - CG)

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

Standard resistance

STANDARD RESISTANCE SPECIFICATION TABLE

Tester Connection	Switch Condition	Specified Condition
6 (CANH) - 4 (CG)	Ignition switch OFF	200 Ω or higher
14 (CANL) - 4 (CG)	Ignition switch OFF	200 Ω or higher

Fig 3: Identifying DLC3 Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: GO TO CHECK CAN BUS LINE FOR SHORT TO GND (See SHORT TO GND IN CAN BUS LINE )

OK: Go to Next Step

CHECK ECUS CONNECTED TO CAN BUS (USING TECHSTREAM)*

Select "CAN Bus Check" from the "System Select".

Wait 1 minute and then check the display of the connected ECUs and sensors.

INSPECTION RESULT REFERENCE TABLE

Inspection Result	Proceed to
All ECUs and sensors connected to CAN communication system displayed on screen.	A
Except for main body ECU, no ECUs connected to MS bus are displayed. Main body ECU outputs MS bus malfunction code (U1002) (MS bus main wire open or short malfunction).	B
No ECUs connected to MS bus are displayed (branch wire between main body ECU and V bus circuit is open).	C
ECU or sensor that should be connected to CAN communication is not displayed (ECU or sensor branch wire open).	D
ECU or sensor that should be connected to CAN communication is not displayed or display is intermittent during check (ECU or sensor branch wire open on one side).	E

NOTE: ECUs and sensors that are not present will not be displayed. Be careful not to mistake them for communication stop malfunctions.

HINT:

If the display of an ECU is intermittent during the check, one side of an ECU or sensor branch wire is open. (The signal of the ECU is treated as noise, which affects the response and display of the Techstream.)
The main body ECU checks for proper ECU communication for ECUs that are connected to the CAN MS bus circuit, and the results are displayed on the Techstream. If communication stops between an ECU and the main body ECU for 10 seconds or more, the ECU disappears from the Techstream display.
For communication stop mode of ECUs connected to the CAN MS bus circuit, refer to the DTC flowchart of the respective communication stop.

B: GO TO DTC U1002 FLOWCHART (See DTC U1002: LOST COMMUNICATION WITH GATEWAY MODULE )

C: GO TO MAIN BODY ECU COMMUNICATION STOP MODE FLOWCHART (See MAIN BODY ECU COMMUNICATION STOP MODE )

D: GO TO PROBLEM SYMPTOMS TABLE (See PROBLEM SYMPTOMS TABLE )

E: GO TO OPEN IN ONE SIDE OF CAN BRANCH WIRE FLOWCHART (See OPEN IN ONE SIDE OF CAN BRANCH LINE )

A: Go to Next Step

CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)*

Select "CAN Bus Check" from the "System Select".

Write down all of the DTCs stored in each ECU.

HINT:

If there are communication malfunction DTCs stored but the intelligent tester's or Techstream's "CAN Bus Check - Communication Bus Check" screen displays all of the ECUs and sensors connected to the CAN system, the communication malfunction DTCs may be past malfunctions that are no longer present.
For V bus main wire malfunctions, related ECUs are also detected. Therefore, determine the malfunctioning area based on all of the DTCs that are output.
For MS bus malfunctions, DTCs are output based on the detection of communication stop malfunctions and network malfunctions of ECUs that are connected by the main body ECU.

INSPECTION RESULT REFERENCE TABLE

Inspection Result	Proceed to
ECU connected to V bus main wire has stored communication malfunction code (V bus main wire past malfunction).	A
Main body ECU outputs MS bus malfunction code (U1002) (MS bus past malfunction).	B
Main body ECU outputs malfunction code other than MS bus malfunction code (U1002) (past malfunction of ECU branch wire connected to MS bus).	C

B: GO TO DTC U1002 FLOW CHART (See DTC U1002: LOST COMMUNICATION WITH GATEWAY MODULE )

C: GO TO PROBLEM SYMPTOMS TABLE (See PROBLEM SYMPTOMS TABLE )

A: Go to Next Step

CHECK DTC COMBINATION TABLE (V BUS CIRCUIT BRANCH WIRE OPEN PAST MALFUNCTION)
1. Based on the combination of stored CAN communication system DTCs, determine which ECUs and sensors have a communication stop malfunction (see DIAGNOSIS SYSTEM ).
PERFORM MALFUNCTION SIMULATION TEST (V BUS CIRCUIT MAIN WIRE PAST MALFUNCTION)*
1. Using the Techstream, clear all DTCs.
2. Perform a malfunction simulation test on all harnesses and connectors related to the V bus circuit main wire.
3. Check the DTCs that were output as a result of the malfunction simulation test. Then determine the malfunctioning area.
ADJUST, REPAIR AND REPLACE
CONFIRMATION TEST
NEXT: END