Mitsubishi Lancer (4A9 engine). Manual — part 235

SECURITY ALARM

CHASSIS ELECTRICAL

54A-602

Inspection Procedure 4: Horns do not sound while the security alarm system is triggered.

CAUTION

Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communica-
tion circuit are normal.

Horn Circuit

ETACS-ECU

RELAYBOX

HORN
RELAY

HORN
(HI)

HORN
(LO)

ENGINE
COMPARTMENT

Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Grey R : Red P : Pink V : Violet PU : Purple SI : Silver

FUSIBLE
LINK

36

38

NOTE

:PETROL
:DIESEL

ACA01093

AC612144

AB

Connector: A-13X <Except RALLIART>

ACA01094AB

Connector: A-13X <RALLIART>

SECURITY ALARM

CHASSIS ELECTRICAL

54A-603

TECHNICAL DESCRIPTION (COMMENT)
If horns do not sound, the horn input signal circuit or
the ETACS-ECU may be defective.

TROUBLESHOOTING HINTS

• Horns may be defective

• Horn relay may be defective

• The ETACS-ECU may be defective

• The wiring harness or connectors may have

loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code.
Check if diagnosis code is set to the ETACS-ECU.

Q: Is the diagnosis code set?

YES :

Diagnose the ETACS-ECU. Refer to

GROUP 54A, Diagnosis .

NO :

Go to Step 2.

STEP 2. Connector check: A-13X horn relay
connector

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the defective connector.

STEP 3. Horn relay check
Refer to .

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Replace the horn relay.

STEP 4. Voltage measurement at the A-13X horn
relay
(1) Remove the relay, and measure at the relay box

side.

(2) Measure the voltage between the A-13X horn

relay connector terminal No. 2, 4 and the body
earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 5.

STEP 5. Wiring harness check between the A-13X
horn relay connector terminal No. 2, 4 and the
fusible link (36) <PETROL> or (38) <DIESEL>
Check the power supply line for open circuit and
short circuit.

Q: Is the check result normal?

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00

− How to

Cope with Intermittent Malfunction ).

NO :

Repair the wiring harness.

STEP 6. Connector check: C-312 ETACS-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the defective connector.

STEP 7. Wiring harness check between the A-13X
horn relay connector terminal No. 1 and the C-
312 ETACS-ECU connector terminal No. 11
Check the output lines for open circuit and short cir-
cuit.

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

Repair the wiring harness.

ACA00916

AB

Connectors: A-42, A-48

A-48 (B)

A-42 (B)

ACA00886

AJ

Connector: C-312 <LHD>
ETACS-ECU

ACA00887

AJ

Connector: C-312 <RHD>
ETACS-ECU

SECURITY ALARM

CHASSIS ELECTRICAL

54A-604

STEP 8. Connector check: A-48 horn (HI)
connector

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair the damaged parts.

STEP 9. Wiring harness check between the A-15X
horn relay connector terminal No. 3 and the A-48
horn (HI) connector terminal No. 1
Check the output lines for open circuit and short cir-
cuit.

Q: Is the check result normal?

YES :

Go to Step 10.

NO :

Repair the wiring harness.

STEP 10. Horn (HI) check

Connect the battery as shown, and verify that the
horn sounds.

Q: Is the check result normal?

YES :

Go to Step 11.

NO :

Replace the horn (HI). go to step 11.

STEP 11. Connector check: A-42 horn (LO)
connector

Q: Is the check result normal?

YES :

Go to Step 12.

NO :

Repair the damaged parts.

STEP 12. Wiring harness check between the A-
13X horn relay connector terminal No. 3 and the
A-42 horn (LO) connector terminal No. 1
Check the output lines for open circuit and short cir-
cuit.

Q: Is the check result normal?

YES :

Go to Step 13.

NO :

Repair the wiring harness.

STEP 13. Check the horn (LO) work normally.

Connect the battery as shown, and verify that the
horn sounds.

Q: Does the horn (LO) work normally?

YES :

Go to Step 14.

NO :

Replace the horn (LO).go to step 14.

STEP 14. Retest the security alarm system.

Q: Does the theft-alarm system work normally?

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00

− How to

Cope with Intermittent Malfunction ).

NO :

Replace the ETACS-ECU.

AC607630

AC607630

SECURITY ALARM

CHASSIS ELECTRICAL

54A-605

Inspection Procedure 5: The activated security alarm siren sounds even though no faulty operation is
made.

CAUTION

Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communica-
tion circuit are normal.

Security Alarm Siren Communication Circuit

ETACS-
ECU

LIN CUTOFF
CONTROL
UNIT

Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Grey R : Red P : Pink V : Violet PU : Purple SI : Silver

ACA00891

AB

Connector: C-63 <LHD>

ACA00896

AB

Connector: C-63 <RHD>

ACA00886

AK

Connectors: C-301, C-312 <LHD>
ETACS-ECU

C-301

C-312

ACA00887

AK

Connectors: C-301 C-312 <RHD>

ETACS-ECU

C-301

C-312