Mitsubishi Colt Ralliart. Manual — part 449

TROUBLESHOOTING

POWER STEERING

37-63

Code No.U1120 Engine-related failure information

CAUTION

• If the electric power steering-ECU sets diagnosis code No.U1120, diagnose the CAN bus lines. If

there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.

•

ENGINE-CVT-ECU

DIAGNOSIS
CONNECTOR

FRONT SIDE

COMBINATION
METER

ABS-ECU

EPS-ECU

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

CAN Communication Circuit

Whenever the ECU is replaced, ensure that the communication circuit is normal.

Main

Index

Group

TOC

TROUBLESHOOTING

POWER STEERING

37-64

TROUBLE JUDGMENT

The electric power steering-ECU receives engine
speed data (crankshaft angle sensor data) from the
engine-CVT-ECU through the CAN bus lines. If the
ECU receives engine speed data (crankshaft angle
sensor data) containing failure information 100 times,
diagnosis code U1120 will be set.

COMMENTS ON TROUBLE SYMPTOM

The M.U.T.-III shows a diagnosis code status as

active

• The crankshaft angle sensor system (of the

engine-CVT-ECU), or the engine-CVT-ECU or
the electric power steering-ECU may be defec-
tive.

The M.U.T.-III shows a diagnosis code status as

stored

• Carry out diagnosis by referring to GROUP 00,

How to Use Troubleshooting/Inspection Service
Points

− How to treat past trouble

P.00-13

. Carry

out diagnosis with particular emphasis on con-
nector(s) or wiring harness in the CAN bus lines
between the engine-CVT-ECU and the electric
power steering-ECU.

NOTE: For a The M.U.T.-III shows a diagnosis code

status as stored, you can not find it by the
M.U.T.-III CAN bus diagnostics even if there is
any failure in CAN bus lines. In this case, refer to
GROUP 00, How to Use Troubleshooting/Inspec-
tion Service Points-How to Cope with Intermittent
Malfunction

P.00-13

and check the CAN bus

lines. You can narrow down the possible cause of
the trouble by referring to the diagnosis code,
which is set regarding the CAN communica-
tion-linked ECUs (Refer to GROUP 54D, CAN
Bus Line Diagnostic Flow

P.54D-7

).

PROBABLE CAUSES

• Defective harness wire(s) or connector(s)

• Malfunction of the engine-CVT-ECU

• Malfunction of the electric power steering-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

AC206895

AC

Diagnosis

connector

MB991827

MB991824

MB991910

CAUTION

Before connecting or disconnecting the
M.U.T.-III, turn the ignition switch to the "LOCK"
(OFF) position.
(1) Connect M.U.T.-III to the 16-pin diagnosis

connector.

(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the CAN bus line (Refer to GROUP
54D, CAN bus line Diagnostic flow

P.54D-13

).

Main

Index

Group

TOC

TROUBLESHOOTING

POWER STEERING

37-65

STEP 2. M.U.T.-III other system diagnosis code

AC206895

AC

Diagnosis

connector

MB991827

MB991824

MB991910

CAUTION

Before connecting or disconnecting the
M.U.T.-III, turn the ignition switch to the "LOCK"
(OFF) position.
Check again if the diagnosis code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Start the engine.
(6) Check that an engine control system diagnosis

code is set.

(7) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Is an engine control system diagnosis code set?

YES :

Diagnose the engine control system (Refer

to GROUP 13A, Troubleshooting

P.13A-20

<4A9>, GROUP 13B,
Troubleshooting

P.13B-18

<4G1>).

NO :

Go to Step 3.

STEP 3. M.U.T.-III other system diagnosis code

AC206895

AC

Diagnosis

connector

MB991827

MB991824

MB991910

CAUTION

Before connecting or disconnecting the
M.U.T.-III, turn the ignition switch to the "LOCK"
(OFF) position.
Check again if the diagnosis code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Start the engine.
(6) Check if a diagnosis code, which relates to CAN

communication-linked systems below, is set.

• Meter

U1120: Diagnosis code indicating engine con-

trol-related failure information

(7) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Is the diagnosis code set?

YES :

Go to Step 4.

NO :

Go to Step 5.

Main

Index

Group

TOC

TROUBLESHOOTING

POWER STEERING

37-66

STEP 4. Check whether the diagnosis code is
reset

AC206895

AC

Diagnosis

connector

MB991827

MB991824

MB991910

CAUTION

Before connecting or disconnecting the
M.U.T.-III, turn the ignition switch to the "LOCK"
(OFF) position.
Check again if the diagnosis code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Recheck whether diagnosis code U1120 is set.
(6) Turn the ignition switch to the "LOCK" (OFF)

position.

(7) Disconnect M.U.T.-III.

Q: Is the diagnosis code set?

YES :

Replace the engine-CVT-ECU (Refer to

GROUP 13A, Engine-CVT-ECU

P.13A-372

).

NO :

A poor connection, open circuit or other
intermittent malfunction is present between
the engine-CVT-ECU and the crankshaft
angle sensor. Refer to GROUP 00, How to
Use Troubleshooting/Inspection Service
Points

− How to Cope with Intermittent

Malfunction

P.00-13

.

STEP 5. Check whether the diagnosis code is
reset

AC206895

AC

Diagnosis

connector

MB991827

MB991824

MB991910

CAUTION

Before connecting or disconnecting the
M.U.T.-III, turn the ignition switch to the "LOCK"
(OFF) position.
Check again if the diagnosis code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Recheck whether diagnosis code U1120 is set.
(6) Turn the ignition switch to the "LOCK" (OFF)

position.

(7) Disconnect M.U.T.-III.

Q: Is the diagnosis code set?

YES :

Replace the electric power steering-ECU

(Refer to

P.37-102

).

NO :

A poor connection, open circuit or other
intermittent malfunction is present between
the engine-CVT-ECU and the crankshaft
angle sensor. Refer to GROUP 00, How to
Use Troubleshooting/Inspection Service
Points

− How to Cope with Intermittent

Malfunction

P.00-13

.

Main

Index

Group

TOC