Mitsubishi Lancer (4A9 engine). Manual - part 209

DC/DC CONVERTER <VEHICLES WITH AUTO STOP & GO (AS&G) SYSTEM>

CHASSIS ELECTRICAL

54A-498

DC/DC CONVERTER <VEHICLES WITH AUTO STOP & GO 

(AS&G) SYSTEM>

SPECIAL TOOL(S)

M1549700100015

DC/DC CONVERTER <VEHICLES WITH AUTO STOP & GO (AS&G) SYSTEM>

CHASSIS ELECTRICAL

54A-499

Tool

Number

Name

Use

MB991955

a. MB991824
b. MB991827
c. MB991910
d. MB991911
e. MB991825
f. MB991826

M.U.T.-III sub-
assembly

a. Vehicle 

Communication 
Interface (V.C.I.)

b. M.U.T.-III USB 

cable

c. M.U.T.-III main 

harness A 
(Vehicles with CAN 
communication 
system)

d. M.U.T.-III main 

harness B 
(Vehicles without 
CAN 
communication 
system)

e. M.U.T.-III measure 

adapter

f. M.U.T.-III trigger 

harness

CAUTION

For vehicles with CAN 
communication, use M.U.T.-III 
main harness A to send 
simulated vehicle speed. If you 
connect M.U.T.-III main harness 
B instead, the CAN 
communication does not 
function correctly.
CAN bus diagnostics, diagnosis 
code or service data check.

MB991223

a. MB991219
b. MB991220
c. MB991221
d. MB991222

Harness set

a. Check harness
b. LED harness
c. LED harness 

adapter

d. Probe

Continuity check and voltage 
measurement at harness wire or 
connector

a. For checking connector pin 

contact pressure

b. For checking power supply 

circuit

c. For checking power supply 

circuit

d. For connecting a locally 

sourced tester

MB991910

MB991826

MB991955

MB991911

MB991824

MB991827

MB991825

a

b

c

d

e

f

DO NOT USE

MB991223

a

d

c

b

DO NOT USE

BA

DC/DC CONVERTER <VEHICLES WITH AUTO STOP & GO (AS&G) SYSTEM>

CHASSIS ELECTRICAL

54A-500

TROUBLESHOOTING

STANDARD FLOW OF DIAGNOSTIC 
TROUBLESHOOTING

M1549700300019

Refer to GROUP 00 

− Contents of troubleshooting .

TROUBLE SYMPTOM CHART

M1549700400016

SYMPTOM PROCEDURES

Inspection Procedure 1: Check the DC/DC converter power supply circuit.

CAUTION

Even when the diagnosis code No. B1301 or B1302 is set in the AS&G-ECU, do not conclude as a DC/
DC converter or AS&G-ECU error, and be sure to check the DC/DC converter power supply circuit.

MB992006

Extra fine probe

Continuity check and voltage 
measurement at harness wire or 
connector

Tool

Number

Name

Use

MB992006

Inspection 
Procedure 
No.

Trouble symptom

Reference 
page

1

Check the DC/DC converter power supply circuit.

2

Audio equipment is reset or sound jump occurs at auto start.

ACA00887

AU

Connectors: C-309, C-313 <RHD> 

C-309 (B)

ETACS-ECU

C-313 (BR)

ACA00886

AV

Connectors: C-309, C-313 <LHD>

ETACS-ECU

C-313 (BR)

C-309 (B)

DC/DC CONVERTER <VEHICLES WITH AUTO STOP & GO (AS&G) SYSTEM>

CHASSIS ELECTRICAL

54A-501

CIRCUIT OPERATION

• The power supply to the DC/DC converter is pro-

vided by the fusible link (36) <Petrol> or (38) 
<Diesel>.

• The ACC signal is received C-65 DC/DC con-

verter connector terminal No.6 from C-313 
ETACS-ECU connector terminal No.9.

PROBABLE CAUSES

• The DC/DC converter connector may be defec-

tive.

• The battery may be defective.

• Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. Battery test
Check the battery state. (Refer to .)

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Replace the battery.

STEP 2. M.U.T.-III ETACS system data list
Check the input signal of ACC relay.

• Turn the ignition switch to the ACC position.

OK: Normal condition is displayed.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Refer to ETACS 

− Input Signal Procedure 1 

"The ignition switch (ACC) signal is not sent 
to the ETACS-ECU" .

STEP 3. Connector check: C-65 DC/DC converter 
connector and C-313 ETACS-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the defective connector.

STEP 4. Voltage measurement at C-65 DC/DC 
converter connector.
(1) Disconnect C-65 DC/DC converter connector, 

and measure at the wiring harness side.

(2) Turn the ignition switch to "ACC" position.
(3) Measure the voltage between terminal No.6 and 

body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Go to Step 6.

STEP 5. Check the harness wire between C-313 
ETACS connector terminal No.1 and C-65 DC/DC 
converter connector terminal No.6.

• Check the signal line for open circuit and short 

circuit.

NOTE: Prior to the wiring harness inspection, check 
C-31 intermediate connector, and repair if necessary.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
use Troubleshooting/inspection Service 
Points, How to Cope with Intermittent 
Malfunction ).

NO : 

Repair the wiring harness.

STEP 6. Voltage measurement at C-65 DC/DC 
converter connector.
(1) Disconnect C-65 DC/DC converter connector, 

and measure at the wiring harness side.

(2) Measure the voltage between terminal No.9 and 

body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Go to Step 7.

Item No.

Item name

Normal 
condition

Item 288

ACC switch

ON

ACA00892

Connectors: C-65 <LHD>

AP

C-65 (GR)

ACA00895AP

Connector: C-65 <RHD>

C-65 (GR)