Home › Power Source/Network › Networking › CAN COMMUNICATION SYSTEM
Last Modified: 11-27-2007 1.6 J
Service Category: Power Source/Network Section: Networking
Model Year: 2008 Model: LX570 Doc ID: RM000002L7Z00EX
Title: NETWORKING: CAN COMMUNICATION SYSTEM: DESCRIPTION (2008 LX570)

Short in CAN Bus Lines

DESCRIPTION

There may be a short circuit between the CAN bus lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom

Trouble Area

Resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.
  • Short between CAN bus lines
  • ECM
  • Center airbag sensor assembly
  • Display and navigation module display*1
  • Multi-display*2
  • AFS ECU (headlight swivel ECU assembly)
  • Air conditioning amplifier assembly
  • Network gateway ECU
  • Main body ECU (cowl side junction block LH)
  • Combination meter assembly
  • No. 1 junction connector
  • No. 2 junction connector
  • No. 3 junction connector

*1: w/ Navigation System

*2: w/o Navigation System

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

Operating the engine 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:

NEXT

2.

CHECK FOR SHORT IN CAN BUS WIRES (DLC3 BRANCH WIRE)

(a) Disconnect the E75 No. 3 junction connector connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E22-6 (CANH) - E22-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

3.

CONNECT CONNECTOR

(a) Reconnect the E75 No. 3 junction connector connector.

NEXT

4.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 JUNCTION CONNECTOR SIDE)

(a) Disconnect the E72 No. 1 junction connector connector.

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

Standard Resistance:

Tester Connection

Switch Condition

Specified Condition

E22-6 (CANH) - E22-14 (CANL)

Engine switch off

108 to 132 Ω
OK

5.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 JUNCTION CONNECTOR - CENTER AIRBAG SENSOR)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E72-4 (CANH) - E72-15 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

6.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 JUNCTION CONNECTOR - AFS ECU)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E72-3 (CANH) - E72-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

7.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 JUNCTION CONNECTOR - ECM)

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

Standard Resistance:

Tester Connection

Switch Condition

Specified Condition

E72-2 (CANH) - E72-13 (CANL)

Engine switch off

108 to 132 Ω
OK

8.

CHECK FOR SHORT IN CAN BUS WIRES (CENTER AIRBAG SENSOR)

(a) Disconnect the E47 center airbag sensor connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E72-4 (CANH) - E72-15 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

9.

CHECK FOR SHORT IN CAN BUS WIRES (AFS ECU)


(a) Disconnect the E91 AFS ECU (headlight swivel ECU) connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E72-3 (CANH) - E72-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

10.

CHECK FOR SHORT IN CAN BUS WIRES (ECM)

(a) Disconnect the A38 ECM connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E72-2 (CANH) - E72-13 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

11.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 1 JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR)

(a) Disconnect the E69 No. 2 junction connector connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E69-1 (CANH) - E69-12 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

12.

CONNECT CONNECTOR

(a) Reconnect the E72 No. 1 junction connector connector.

NEXT

13.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 JUNCTION CONNECTOR SIDE)


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

Standard Resistance:

Tester Connection

Switch Condition

Specified Condition

E22-6 (CANH) - E22-14 (CANL)

Engine switch off

108 to 132 Ω
OK

14.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 JUNCTION CONNECTOR - DISPLAY AND NAVIGATION MODULE DISPLAY OR MULTI-DISPLAY)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E69-2 (CANH) - E62-13 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

15.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 JUNCTION CONNECTOR - AIR CONDITIONING AMPLIFIER)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E69-5 (CANH) - E69-16 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

16.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 JUNCTION CONNECTOR - NETWORK GATEWAY ECU)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E69-3 (CANH) - E69-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

17.

CHECK FOR SHORT IN CAN BUS WIRES (DISPLAY AND NAVIGATION MODULE DISPLAY OR MULTI-DISPLAY)

(a) Disconnect the F28 display and navigation module display*1 or multi-display*2 connector.

    *1: w/ Navigation System

    *2: w/o Navigation System

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

Result

Tester Connection

Switch Condition

Measured Resistance

Result

Type

Proceed to

E69-2 (CANH) - E69-13 (CANL)

Engine switch off

1 Ω or higher

OK

w/ Navigation System

A

w/o Navigation System

B

Below 1 Ω

NG

-

C
A

18.

CHECK FOR SHORT IN CAN BUS WIRES (AIR CONDITIONING AMPLIFIER)

(a) Disconnect the E35 air conditioning amplifier connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Result

E69-5 (CANH) - E69-16 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

19.

CHECK FOR SHORT IN CAN BUS WIRES (NETWORK GATEWAY ECU)

(a) Disconnect the E31 network gateway ECU connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E69-3 (CANH) - E69-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

20.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 JUNCTION CONNECTOR - NO. 3 JUNCTION CONNECTOR)

(a) Disconnect the E75 No. 3 junction connector connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E75-1 (CANH) - E75-12 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

21.

CONNECT CONNECTOR

(a) Reconnect the E69 No. 2 junction connector connector.

NEXT

22.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 3 JUNCTION CONNECTOR - MAIN BODY ECU)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E75-4 (CANH) - E75-15 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

23.

CHECK FOR SHORT IN CAN BUS WIRES (NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E75-3 (CANH) - E75-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

24.

CHECK FOR SHORT IN CAN BUS WIRES (MAIN BODY ECU)

(a) Disconnect the E3 main body ECU (cowl side junction block LH) connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E75-4 (CANH) - E75-15 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK

25.

CHECK FOR SHORT IN CAN BUS WIRES (COMBINATION METER)

(a) Disconnect the E77 combination meter connector.

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

Result

Tester Connection

Switch Condition

Measured Resistance

Proceed to

E75-3 (CANH) - E75-14 (CANL)

Engine switch off

1 Ω or higher

OK

Below 1 Ω

NG
OK