check engine light MITSUBISHI ECLIPSE 1991 Service Manual

I4INTRODUCTION AND MASTER TROUBLESHOOTING - Precautions before Service
mm (In.1smo59
PARTSWhen replacing parts, use MOPAR genuine parts.
VEHICLE WASHING
If high-pressure car-washing equipment or steam car-washing
equipment is used to wash the vehicle, be sure to maintain the
spray nozzle at a distance of at least 300 mm (12 in.) from anyplastic parts and all opening parts (doors, luggage compart-
ment, etc.).
SERVICING ELECTRICAL SYSTEM
1. Note the following before proceeding with work on the
electrical system.
Note that the following must never be done:
Unauthorized modifications of any electrical device or
wiring, because such modifications might lead to a vehicle
malfunction, over-capacity or short-circuit that could result
in a fire in the vehicle.
2. When servicing the electrical system, disconnect the
negative cable terminal from the batten/.
Caution1. Before connecting or disconnecting the negative
cable, be sure to turn off the ignition switch and thelighting switch.
(If this is not done, there is the possibility of
semiconductor parts being damaged.)
2. For MPI-equipped models, after completion of the
work steps [when the battery’s negative
(-) termi-
nal is connected], warm up the engine and allow it
to idle for approximately five minutes under the
conditions described below, in order to stabilize
engine control conditions, and then check to be
sure that the idling is satisfactory.
Engine coolant temperature:
85-95°C (185-203°F)
Lights, electric fans, accessories: OFF
Transaxle: neutral position
(A/T models: “N” or “P”)
Steering wheel: neutral (center) position

BRAKES - Anti-lock Braking System Troubleshooting5-9
ANTI-LOCK BRAKING SYSTEM
-- TROUBLESHOOTINGNO!JEBAE
PARTICULAR CHARACTERISTICS OF
THE ANTI-LOCK BRAKING SYSTEMModels equipped with the anti-lock braking system
(A.B.S.) may exhibit one or more of the following
characteristics from time to time, but none of these
is abnormal.
(1) A pulsing feeling in the brake pedal, or vibration
of the body or the steering wheel, when the
anti-lock braking system is activated by sudden
braking or by braking on a slippery road surface.Actually, this phenomenon is an indication that
the anti-lock braking system is functioning nor-
mally.(2) When the vehicle speed reaches approximately
6 km/h (4 mph) after the engine is started and
the vehicle starts off (for the first time), a
whining motor noise may be heard from the
engine compartment if the vehicle is traveling in
a quiet place, but this noise is simply the result
of a self-check being made of the anti-lock
braking system operation.
TROUBLESHOOTING METHODSProblems related to the anti-lock braking system
(A.B.S.) can be classified into two general categor-
ies: problems in the electrical system and those in
the hydraulic system.For problems in the electrical system, the
self-diagnosis function is built into the electronic control
unit (E.C.U.) causing the A.B.S. warning light to
illuminate as a warning to the driver.
Problems in the hydraulic system (poor braking,
etc.) can be located in the same way as for ordinary
brakes. There is, however, the necessity to check todetermine whether the problem is related to ordin-
ary brake components or to the components relatedto the A.B.S.
HOW TO USE THE TROUBLESHOOTING
FLOW CHART(1) Using the flow chart, check the ABS warning
light light-up sequence and check the condition
of braking operation.
(2) Following the check chart listed in the remedy
column, perform the checks. There are [Explana-tion] and [Hint] in each check chart. Refer to
them when troubleshooting.
NOTEECU: Electronic control unit
HU: Hydraulic unit
MUT: Multi-use tester

Ioes the ABS warning light illuminate as describedbelow up to the time the engine starts?
1) When the ignition key is turned to the “ON”
position, the ABS warning light illuminates for
approximately 1 second due to the ABS ECU (asa self check of the valve relays is performed),
then it blinks twice and goes out and stays out.
2) With the ignition key in the “START” position,
power to the ABS ECU is interrupted and the
5-10BRAKES - Anti-lock Braking System Troubleshooting
TROUBLESHOOTING (ABS-FWD)Confirm condition in the following way and diagnosis accordingly.
ABS warning light remains lit because the valve
relay is OFF.
(3) When the ignition key is turned from the
“START” position to the “ON” position, the
ABS warning light illuminates for approximately
1 second (during this time a recheck of the valverelays is performed), then it blinks twice and
then goes out and stays out.
ABS warning
lightON
OFF
1Ignition
kev
ST
ON
ACC, LOCK
IYes
CONTINUE TO NEXT PAGE
No
No.Trouble condition
ABS warning light does not light up at all.
ON
1 --ABSwarningOFF
1lightlgnitlon
kev
14A0590When the ignition key is turned to the
“ON” position, it remains lighted.
ABSwarning
2light
Ignition
kevACC,
LO:+14AOSQlDoes not illuminate when ignition key is
in “START” position.
ABSONwarning
3lightOFFUULkev ACC.
LO:-+-Ignition14A0592
1 sec. 1 sec.1 sec.1 sec.
---
IIII
3114AO589
IMajor causes
l ABS warning light bulb is burnt out.Check, using flow
l Open in ABS warning light electricalchart A (Refer to P.5-
circuit (check for blown fuse)12.)
l Fail safe is functioning due to ECU selfdiagnosis
o Short in ECU warning light drive circuitl Malfunction of ECU
l Malfunction of valve relayl Break in harness between ABS warn-
ing light and HU
l Break in harness between HU and
body groundRemedy
Check, using flow
chart
B (Refer to P.5-
15.)
Check, using flow
chart C (Refer to P.5-17.)

BRAKES - Anti-lock Braking System Troubleshooting5-13With the ignition key in the “ON”
posi-Nol
tion, do other warning lights illuminate?
II
YesCheck fuse No. 11. If it is
blown, correct the cause of
the blown fuse and then
replace the fuse.
Does voltage between
har-NoThe harness between thenessconnector terminalcombination meter from
No. 14 and ground indicate) fuse No.1 1 is broken.
battery voltage?
II
Yes
Repair harness.Circuit in combination meter
is broken.Repair or replace
com-
* bination meter.
Turn the ignition switch OFF an
(check.
IIs the ABS warning light normal? (Check
for burned bulb.)
No L A&zed%rning light bulb -Are instrument panel wiring harness,
_Noengine compartment wiring harness,~ Connect connectors firmly.
(Check for pins pulled out or
bent, repair as needed.) body wiring harness and ABS wiring
harness connectors connected properly?drive circuits. Check and repair both

BRAKES - Anti-lock Braking System Troubleshooting5-15
--
BABS warning light illuminated after the engine is started and remains on.
[Explanation]
This is the symptom when the ABS ECU does not
power up due to broken ECU power circuit, etc.,
when the fail safe function operates and isolates thesystem or when the warning light drive circuit is
short circuited.
MAINIGNITION
FUSIBLELINK
@IEYCH
z
A:7
J/B
rb
0
10A
I
:c
r
I
1vAI23
f
! 127ABS ECUCheck, using check chart
E-l -E-6.Check warning light drive
circuit.
t
Does the ABS warning lightNoShort in ECU transistor
remainilluminated even
with the ECU connector dis-
connected?
I
1 YesIReplace
I
Does the ABS warning light
remainilluminated even
with the ECU connector dis-
connected?
Yes
IReplace HU or replacevalve relay.I

5-24BRAKES - Anti-lock Braking System Troubleshooting
E-6 Abnormality of motor drive circuit
[Explanation]The ABS ECU illuminates the warning light for the
motor relay and motor in the following cases.
l When the motor relay does not function
lWhen there is trouble with the motor itself and it
does not revolve
lWhen the motor ground line is disconnected and
[Hint]If there is motor operation noise when wheel speed
exceeds
Gkm/h (4mph) when starting up after the
engine is started, there is a broken or short circuitedmotor monitor wire.
the motor does not revolve
l When the motor continues to revolve
14A0605Does the motor make a
YesBroken wire or short cir-noise when wheel speedcuit in motor monitor line
exceeds 6 km/h (4 mph)?
1Repair the harness be-
tween HU and ECU.
, NoRemove the motor relay.
Remove the motor relay andcheck resistance values.
No. 85-No. 86:resistancevalue
30-60 52No.30-No.87: no continui-
ty
Battery voltage is applied onterminals No. 86 and No.85
grounded.No.30-No.87: continuity
IYesIs pump motor ground con-
NoConnect ground wire.
netted normally?
IlYes
motor relay and re-
move HU connector.>Does voltage between body
connector terminal 51 and
No c Broken wire in pump
motor power circuit
ground indicate battery vol-
tage?4Repair the harness.
YesIs resistance between body
NoMalfunction of harnessconnector terminal No. 2 andbetween HU and ECUNo.26 30-60 ohms?iII1Repair harness.

BRAKES - Anti-lock Braking System Troubleshooting5-25
TROUBLESHOOTING (ABS-AWD)Confirm condition in the following way and diagnosis accordingly.
C
F
>oes the ABS warning light illuminate as described
relow up to the time the engine starts?
1) When the ignition key is turned to the “ON”
position, the ABS warning light illuminates for
approximately 1 second due to the ABS ECU (asa self check of the valve relays is performed),
then it blinks four times and goes out and stays
out.power to the ABS ECU is interrupted and the
ABS warning light remains lit because the valve
relay is OFF.
t:2) With the ignition key in the “START” position,(3) When the ignition key is turned from the
“START” position to the “ON” position, the
ABS warning light illuminates for approximately
1 second (during this time a recheck of the valverelays is performed), then it blinks four times
and then goes out and stays out.IO1
-1 sec. 1 sec.1
sec.1 sec.
14AO594
YesCONTINUE TO NEXT PAGE
No
No.
1
2
3
Trouble condition
ABS warning light does not light up at all.
ABSwarninglightOFFIgnitionkey
ACC.
LO;-+
14AOSSOWhen the ignition key is turned to the
“ON” position, it remains lighted.
4BSNamingight
0:7gnition
wACC.
LO:+14A0591Does not illuminate when ignition key is
in “START” position.
4BSNamingightONOFF
14A0595
Major causes
l ABS warning light bulb is burnt out.
l Open in ABS warning light electrical
circuit (check for blown fuse)
l Fail safe is functioning due to ECU self
diagnosis
l Short in ECU warning light drive circuitl Malfunction of ECU
l Malfunction of valve relay
l Break in harness between ABS warn-
ing light and HU
l Break in harness between HU and
body groundRemedy
Check, using flow
chart A. (Refer to
P.5-27.)
Check, using flow
chart B. (Refer to P.5-30.)
Check, using flow
chart C. (Refer to
P.5-
32.)

5-28BRAKES -Anti-lock Braking System Troubleshooting
With the ignition key in the “ON”
posi-NoCheck fuse No.ll. If it is
tion, do other warning lights illuminate?blown, correct the cause of
the blown fuse and then
replace the fuse.
YesTurn the ignition switch OFF and
Does voltage between
har-NOThe harness between the
nessNo. 14 and ground indicate
battery voltage?) fuse No.1 1 is broken.
YesCircuit in combination meter
is broken.
tRepair or replace com-
bination meter.II
IIIs the ABS warning light normal? (CheckNO) ABS warning light bulbReplace ABS warning
for burned bulb.)
burned.* light bulb.
I
Yes
- No
Are instrument panel wiring harness,
engine compartment wiring harness,
body wiring harness and ABS wiring
harness connectors connected properly?
c Connect connectors firmly.
(Check for pins pulled out or
bent, repair as needed.)
YesBroken wire in ECU, valve relay or both
drive circuits. Check and repair both
circuits.

5-30BRAKES - Anti-lock Braking System Troubleshooting
BABS warning light illuminated after the engine is started and remains on.
[Explanation]This is the symptom when the ABS ECU does not
power up due to broken ECU power circuit, etc.,
when the fail safe function operates and isolates thesystem or when the warning light drive circuit is
short circuited.
MAINIGNITIONFUSIBLELINK
@SWITCH(IGl)
ABS ECU
JCheck, using check chart
E-l -E-7.with the ECU connector
dis-
YesDoes the ABS warning light
NoShort in HU harness or
remainilluminated even
with the ECU connector dis-m sticking of valve relay
contact
connected?I
YesReplace HU or replace
valve relay.
ItShort in harness between
IT$Uhx ECU and ABS warningc Repair harness or replace
combination meter.

5-40BRAKES - Anti-lock Braking System Troubleshooting
E-7Abnormality of motor drive circuit
[Explanation]The ABS ECU illuminates the warning light for the
motor relay and motor in the following cases.
l When the motor relay does not function
lWhen there is trouble with the motor itself and it
does not revolve
[Hint]If there is motor operation noise when wheel speed
exceeds
Gkm/h (4mph) when starting up after the
engine is started, there is a broken or short circuitedmotor monitor wire.
lWhen the motor ground line is disconnected andthe motor does not revolve
l When the motor continues to revolve
Does the motor make a
YesBroken wire or short cir-noise when wheel speed
-cuit in motor monitor line
exceeds 6 km/h (4 mph)?
b
NoRepair the harness between HU and ECU.
emove the motor rela
ABS ECU
14A0105
Remove the motor relav and
check resistance values.
No.
85-No. 86:resistancevalue 30-60 QNo.30-No.87: no continui-
ty
Battery voltage is applied on
terminals No. 86 and No. 85
grounded
No. 30-No. 87: continuity
Yes
q Motor relay malfunction 1
Replace motor relay.I
Is pump motor ground con-netted normally?Connect ground wire.I
b
Does voltage between bodyNo
connector terminal 51 andIBroken wire in pumpmotor power circuit
ground indicate battery vol-
tage?1Repair the harness.
YesIs resistance between body
- No L Malfunction of harness
connector terminal No. 2 andbetween HU and ECU
No.26 30-60 ohms?b
YesRepair harness.
Motor drive circuit is normal.