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Home >> Toyota Truck >> 2011 >> Sequoia 4WD V8-4.6L (1UR-FE) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Information Bus >> Testing and Inspection >> Component Tests and General Diagnostics >> Short to B+ in CAN Bus Line >> Part 1

Part 1





NETWORKING: CAN COMMUNICATION SYSTEM: Short to B+ in CAN Bus Line
- Short to B+ in CAN Bus Line

DESCRIPTION

There may be a short circuit between the CAN bus line and +B when there is resistance between terminals 6 (CANH) and 16 (BAT) or terminals 14 (CANL) and 16 (BAT) of the DLC3.





*1: w/ Bus Buffer ECU

*2: w/ 4WD

*3: w/ Air Suspension

*4: w/ Dynamic Laser Cruise Control System

WIRING DIAGRAM









INSPECTION PROCEDURE

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

PROCEDURE

1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL

(a) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.

CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

NOTICE:
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.

NEXT -- Continue to next step.

2. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (DLC3 BRANCH WIRE)

(a) Disconnect the H119 No. 1 junction connector.





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

Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO DLC3 (CANH, CANL)
OK -- Continue to next step.

3. CONNECT CONNECTOR

(a) Reconnect the H119 No. 1 junction connector.

NEXT -- Continue to next step.

4. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 2 JUNCTION CONNECTOR SIDE)

(a) Disconnect the H116 No. 2 junction connector.





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

Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 1 JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR)
OK -- Continue to next step.

5. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 2 JUNCTION CONNECTOR - AIR CONDITIONING AMPLIFIER)

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





Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.

6. SYSTEM CHECK

(a) Check the vehicle specifications.

Result





B -- SYSTEM CHECK
A -- Continue to next step.

7. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 2 JUNCTION CONNECTOR - BUS BUFFER ECU)

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





Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (BUS BUFFER ECU)
OK -- Continue to next step.

8. SYSTEM CHECK

(a) Check the vehicle specifications.

Result





B -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 2 JUNCTION CONNECTOR - ECM)
A -- Continue to next step.

9. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 2 JUNCTION CONNECTOR - 4WD CONTROL ECU)

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





Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (4WD CONTROL ECU)
OK -- Continue to next step.

10. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 2 JUNCTION CONNECTOR - ECM)

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





Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (ECM)

OK -- REPAIR OR REPLACE NO. 2 JUNCTION CONNECTOR

11. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (AIR CONDITIONING AMPLIFIER)

(a) Disconnect the H24 air conditioning amplifier connector.





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

Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO AIR CONDITIONING AMPLIFIER (CANH, CANL)

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

12. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (BUS BUFFER ECU)

(a) Disconnect the H66 bus buffer 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 BRANCH WIRE CONNECTED TO BUS BUFFER ECU (CAN+, CAN-)

OK -- REPLACE BUS BUFFER ECU

13. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (4WD CONTROL ECU)

(a) Disconnect the A28 4WD control 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 BRANCH WIRE CONNECTED TO 4WD CONTROL ECU (CANH, CANL)

OK -- REPLACE 4WD CONTROL ECU Removal

14. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (ECM)

(a) Disconnect the A27 ECM connector.





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

Standard Resistance:





Text in Illustration





Result





D -- REPLACE ECM Removal

C -- REPLACE ECM Removal

B -- REPLACE ECM Removal

A -- REPAIR OR REPLACE CAN MAIN WIRE CONNECTED TO ECM (CANH, CANL)

15. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 1 JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR)

(a) Disconnect the H119 No. 1 junction connector.





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

Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 1 JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR)
OK -- Continue to next step.

16. CONNECT CONNECTOR

(a) Reconnect the H119 No. 1 junction connector.

(b) Reconnect the H116 No. 2 junction connector.

NEXT -- Continue to next step.

17. SYSTEM CHECK

(a) Check the vehicle specifications.

Result





B -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 1 JUNCTION CONNECTOR - COMBINATION METER ECU)
A -- Continue to next step.

18. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 4 JUNCTION CONNECTOR SIDE)

(a) Disconnect the O41 No. 4 junction connector.





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

Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 1 JUNCTION CONNECTOR - NO. 4 JUNCTION CONNECTOR)
OK -- Continue to next step.

19. CONNECT CONNECTOR

(a) Reconnect the O41 No. 4 junction connector.

NEXT -- Continue to next step.

20. CHECK FOR SHORT TO B+ IN CAN BUS WIRE (NO. 4 JUNCTION CONNECTOR - SUSPENSION CONTROL ECU)

(a) Disconnect the O42 No. 4 junction connector.





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

Standard Resistance:





Text in Illustration





NG -- CHECK FOR SHORT TO B+ IN CAN BUS WIRE (SUSPENSION CONTROL ECU)
OK -- Continue to next step.
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