Mitsubishi Colt Ralliart. Manual - part 299

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54D-25

FUNCTION

When diagnosing the CAN bus lines, the M.U.T.-III 
measures the voltage of CAN_H and CAN_L line and 
detects the short to power supply or earth.

TROUBLE JUDGEMENT CONDITIONS

The M.U.T.-III judges the trouble when it is impossi-
ble to receive the periodically sent data and the volt-
age of CAN_H or CAN_L line is more than 4.0 volts.

POSSIBLE CAUSES

• Malfunction of the wiring harness

• Malfunction of the connector

• Malfunction of each ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the CAN bus lines. Voltage 
measurement at B-32 diagnosis connector.

CAUTION

A digital multimeter should be used. For details 
refer to 

P.54D-5

.

CAUTION

The test wiring harness should be used. For 
details refer to 

P.54D-5

.

NOTE: This inspection allows you to check that there 
is a short to power supply in either CAN_H line or 
CAN_L line. Thus, in the following steps, check the 
CAN bus line that is defective.

AC509191

Connector: A-08

Harness side

AD

A-08 (GR)

AC401056

AB

Connectors: B-15, B-32

B-32 (B)

Harness side

B-32

B-15

Harness side

B-15 (B)

(1) Disconnect engine-ECU <M/T> or 

engine-CVT-ECU <CVT> connector A-08 and 
combination meter connector B-15, and measure 
the voltage at the harness side of diagnosis 
connector B-32.

Main

Index

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TOC

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54D-26

(2) Connect the negative battery terminal, and turn 

the ignition switch to the ON position.

AC313907

AC313907 AC

harness side: B-32

Test 
Harness

(3) Voltage between B-32 diagnosis connector 

terminal No.14 and body earth (CAN_H)

OK: 4.0 V or less

AC313907 AB

Harness side: B-32

Test 
harness

(4) Voltage between B-32 diagnosis connector 

terminal No.6 and body earth (CAN_L)

OK: 4.0 V or less

(5) Disconnect the negative battery terminal.

Q: Is the check result normal?

YES : 

<Both of the measurement results show 4.0 

V or less> Go to Step 10.

NO : 

<Either of CAN_H line or CAN_L line the 
measurement results show 4.0 V or less> 
Go to Step 2.

STEP 2. Voltage measurement at B-40 
intermediate connector.

CAUTION

A digital multimeter should be used. For details 
refer to 

P.54D-5

.

CAUTION

The test wiring harness should be used. For 
details refer to 

P.54D-5

.

AC313820

Connector: B-40

AD

(1) Disconnect intermediate connector (B-40), and 

measure at its female-side intermediate 
connector (at the front wiring harness side).

(2) Connect the negative battery terminal, and turn 

the ignition switch to the ON position.

AC313907 AD

Female side: B-40

Test 
harness

(3) Voltage between B-40 intermediate connector 

terminal No.3 and body earth (CAN_H)

OK: 4.0 V or less

AC313907 AE

Female side: B-40

Test 
harness

(4) Voltage between B-40 intermediate connector 

terminal No.4 and body earth (CAN_L)

OK: 4.0 V or less

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TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54D-27

(5) Disconnect the negative battery terminal.

Q: Is the check result normal?

YES : 

<4.0 V or less> Go to Step 7.

NO : 

<more than 4.0 V> Go to Step 3.

STEP 3. Resistance measurement at B-03 joint 
connector (CAN1).

CAUTION

A digital multimeter should be used. For details 
refer to 

P.54D-5

.

CAUTION

The test wiring harness should be used. For 
details refer to 

P.54D-5

.

AC313820

Connector: B-03

AE

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Connect the negative battery terminal, and turn 

the ignition switch to the ON position.

(3) Measure the voltage between each of B-03 joint 

connector (CAN1) terminals and body earth.

Main

Index

Group

TOC

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54D-28

<CAN_H>

•

AC313907AF

Harness side: B-03

Test 
harness

Terminal No.2 and body earth

•

AC204738

AC204738

AC204738NA

Harness side: B-03

Test 
harness

Terminal No.6 and body earth <vehicles with 

ASC>

•

AC313907

AC313907AI

Harness side: B-03

Test 
harness

Terminal No.8 and body earth

•

AC313907

AC313907AJ

Harness side: B-03

Test 
Harness

Terminal No.7 and body earth

OK: 4.0 V or less

<CAN_L>

•

AC313907

AC313907AG

Harness side: B-03

Test 
harness

Terminal No.3 and body earth

•

AC313907

AC313907AH

Harness side: B-03

Test 
harness

Terminal No.4 and body earth

•

AC313907

AC313907AL

Harness side: B-03

Test 
harness

Terminal No.11 and body earth

•

AC204738

AC204738

AC204738NB

Harness side: B-03

Test harness

Terminal No.12 and body earth <vehicles with 

ASC>

OK: 4.0 V or less

(4) Disconnect the negative battery terminal.

Main

Index

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TOC